Huletts Refinery has been supplying AECI Bioproducts with high-test molasses for use as a fermentation feedstock in the manufacture of lysine. Due to the high ash content in the high-test molasses, the lysine plant has experienced bottlenecks in the process. A process to remove the ash was jointly developed by Tongaat-Hulett Sugar Ltd and AECI Bioproducts and a commercial plant using continuous ion exchange technology (ISEP) has been installed at Huletts Refinery. The de-ashing process uses a strong acid cation followed by a weak base anion resin.

The principles of ISEP technology, aspects of piloting, features of the commercial plant design, and the operation and performance of the plant are described in this paper.

ENHANCEMENT OF SUGAR PRODUCTION

PART 1: PRODUCTION OF WHITE SUGARAND CLEAN MOLASSES IN THE RAW HOUSE

Dr PI Bekker, ² HNP Stolz,^1+
2

Transvaal Sugar Limited,PO Box 47, Malelane 1320

Abstract

The application of technologies such as cross-flow filtration and polymeric resins to remove high molecular weight particles and colour as well as colour forming substances from clear juice, enables the production of white sugar in the raw house and a lower colour, sludge-free molasses. The technical and economic viabilities of the enhancement of sugar production in the raw house are based on extensive experimental evaluations carried out on a pilot scale, at the Komati Mill, since 1996.

SOIL COMPACTION AND ITS MANAGEMENT

W A J Berry

KwaZulu Natal Department of Agriculture and Environmental Affairs

Abstract

The compaction of soils used for crop production is becoming an increasingly important consideration in South Africa following the shift towards reduced tillage and increased mechanisation of in-season operations and harvesting. This paper addresses factors which contribute to soil compaction, considers errors made in identifying compaction, and proposes methods for testing and alleviating compaction. Soils are most vulnerable to compaction when they are close to the field capacity water content. Topsoils with clay contents less than 20 % are easily compacted, and careful management of these soils, such as controlled trafficking of lands, and regular testing for compaction and its rectification through tillage, will ensure that soil productivity is maintained. One common error when testing for soil compaction is to force a sharpened steel probe into the soil to test for hard layers. This method is only successful if the whole profile has been allowed to become wet to the field capacity water content, otherwise known as the drained upper limit (DUL). Correct testing for compaction may help to reduce production costs through indiscriminate tillage.

Keywords: soil compaction, testing for compaction, correcting compaction

CROP FORECASTS IN THE LIGHT OF THE SOUTH AFRICAN SUGAR INDUSTRY'S

OPERATIONAL REQUIREMENTS

CN Bezuidenhout

South African Sugar Association Experiment Station, P/Bag X02, Mt. Edgecombe, 4300, South Africa

Short communication for the 75^th SASTA Congress

The South African sugar industry can gain economically when decision makers use accurate and timely crop forecasts to support decisions. Recent studies at the University of Natal illustrated large economic benefits in using models for predicting yield. The model approach showed significant improvements in accuracy over conventional methods of forecasting on the regional Eston mill area scale. Model based operational forecasts by the SASA Experiment Station have also shown the ability to deliver frequent forecasts for large combinations of soil, climate and management parameters. However, it is important that forecast information is distributed at the right time and in the right format. Consequently a survey was conducted in which stakeholders in the agricultural, milling and services sectors were given the opportunity to state their requirements by completing a questionnaire. The questionnaire addressed issues such as forecast frequency, timing, accuracy, geographical resolution and information transfer media. This short communication will present some of the results obtained from the survey to stimulate further discussion.

METABOLIC MODELLING OF SUCROSE METABOLISM: A POWERFUL PREDICTIVE TOOL FOR GENETIC MANIPULATION OF SUGAR CONTENT IN SUGARCANE

F.C. Botha¹ and J. Rohwer²

¹Institute for Plant Biotechnology, University of Stellenbosch, Private Bag X1, Matieland, 7602, ² Biochemistry Department, University of Stellenbosch, Private Bag X1, Matieland, 7602

(Short Communication)

The apparent failure to make significant progress in raising the sucrose content of commercial varieties during the last two decades has led to the speculation that a yield plateau has been reached. Several research groups have therefore been looking at genetic manipulation of sucrose metabolism as an alternative approach to supplement conventional breeding. However, the general lack of knowledge regarding the complexity of sucrose metabolism, and the control of sugar accumulation, makes the selection of candidate genes for manipulation extremely difficult. Over the past few years we have accumulated a significant amount of information about carbon partitioning, enzyme and metabolite levels, and metabolic fluxes in the sugarcane culm. This information was used to develop a kinetic metabolic model of sucrose synthesis and breakdown in the culm. The model accurately simulates the characteristic sucrose accumulation pattern observed in sugarcane. Surprisingly, the model predicted limited control on sucrose metabolism for some of the current genes being targeted for manipulation. By referring to the example of genetically modified sugarcane with reduced acid invertase, it will be illustrated that this model could become an invaluable tool in developing a strategy to manipulate metabolism in sugarcane.

This work was supported by the South African Sugar Industry and the Foundation for Research Development.

USING COMMERCIAL FIELD RECORDS TO CATEGORISE SUGARCANE PRODUCTION POTENTIAL AND DERIVATION TO PREDICT ACTUAL SUGARCANE YIELDS

EA Brüggemann ^a*, JR Klug ^a, PL Greenfield ^a and HM Dicks ^b

^a School of Agricultural Sciences and Agribusiness

^b School of Mathematics, Statistics and Information Technology

University of Natal, Private Bag X01, Scottsville, 3209

Abstract

Commercial sugarcane records for 19 seasons from 146 fields were obtained from five estates in the KwaZulu-Natal Midlands. Extensive editing and cleaning of the estate agronomic records was required. Regression models were developed, and depending on the predictor variables selected, the best model accounted for 55% of the observed yield variation, based on 535 crop cycles. Linear regression was an appropriate analytical technique since the assumptions of normality and homoscedasticity were upheld and multicollinearity was not an issue in the models. The final models were validated using an independent data set of 47 observations and satisfactory performances were confirmed. The 95% confidence limits of yield predictions for the population mean were within 10% of long-term mean yields and could be useful for resource allocation and harvest planning at an estate level. One model was linked to a geographic information system to demonstrate the expected yield response to physical field properties, identifying areas of differing production potential at a general scale within estates. Reliable yield predictions for individual fields could not be made and within-field resource variations could not be adequately accounted for. Key physical field attributes associated with sugarcane yield were locality, aspect, altitude, soil type and effective rooting depth. Season and rainfall were important climatic variables. Of the factors influenced by management, sugarcane variety, plant-ratoon status, crop cycle, N and K nutrition and the topsoil Ca:Mg ratio were important yield predictors. The relative importance of individual predictors varied with the specific combination of resources for a particular observation.

Preliminary investigation into the EFFECT of PLANT nutrient levels on flowering at Mount Edgecombe

MJ Brunkhorst

South African Sugar Association Experiment Station, Private Bag X02,

Mount Edgecombe, 4300, South Africa

Abstract

The successful initiation and emergence of flowers is vital for the generation of new sugarcane varieties. A number of factors, which include the parent variety, temperature, moisture and the photoperiod treatment, all have varying levels of influence on flowering. A factor, which in the past has not received much attention, is the effect of nutrition. Over the past two crossing seasons at Mount Edgecombe, leaf samples have been collected from control varieties in each of nine photoperiod treatments and analysed for various nutrients including nitrogen, phosphorus and potassium. In this paper, preliminary results of the effect of various nutrients on numerous aspects of flowering in sugarcane are reported.

THE YIELD PERFORMANCE OF VARIETIES N23 AND N25 ON DUPLEX SOILS IN SWAZILAND

DWF BUTLER

Swaziland Sugar Association, PO Box 367, Simunye, Swaziland

Abstract

South African varieties N25 and N23 were compared on soils with low yield potential against industry standards NCo376 and N19 in four replicated, irrigated trials comprising a total of 17 crops, harvested either early or late in the milling season. Chemical ripeners ethephon (2-chloroethane-phosphonic acid) and Fusilade Super (fluazifop-p-butyl) were applied either alone or as a combination treatment in all early season experiments, while only Fusilade Super was applied in late season experiments when conditions allowed.

These varieties tended not to respond to chemical ripeners when grown on duplex soils. This was probably because of poor growing conditions when ripeners were applied. The mean sucrose yield of N25 was consistently higher than that of the other varieties in both early and late season experiments, indicating that it is better suited to poor soil conditions than the current industry standards. In early season experiments, N23 did not yield as much sucrose as either N25 or NCo376, indicating that its potential may be restricted to more productive soils. These results add to published yield data for varieties N23 and N25 grown on soils with medium to high yield potential in Swaziland.

THE SUGARCANE GENOME : A SYNTHESIS OF CURRENT UNDERSTANDING, AND LESSONS FOR BREEDING AND BIOTECHNOLOGY

MK Butterfield¹ and A D’Hont²

¹ SASA Experiment Station, Pvt Bag X02, Mt Edgecombe, 4300, South Africa, email: xpbrmb@sugar.org.za

² CIRAD, BP 5035, F-34032 Montpellier cedex 1, France.

Abstract

An understanding of the Saccharum genome and insight into its evolution and organisation is necessary for making informed decisions in breeding, germplasm introgression and biotechnology. Over the last 80 years, much has been learned about the sugarcane genome from cytological studies, breeding experiments, chemotaxic markers, and more recently from molecular diversity studies, DNA mapping, and molecular cytogenetics. In addition, detailed DNA mapping and sequencing studies in other plants can provide further clues to genome organisation in sugarcane. In the first part of this report, information from published sources is reviewed to produce a synthesis of current knowledge regarding the Saccharum genome, and from this a working model of the genome of modern hybrid sugarcane is proposed. It is clear that there are important gaps that require filling before a complete picture of the genome organisation is obtained. In the second part of this report, the working model is used to re-assess some of the conceptual structures used in sugarcane breeding and biotechnology. From this, some new approaches are suggested which aim to assist in the development of improved breeding strategies, germplasm introgression programmes and research strategies for biotechnology.

ANNUAL AND LONG TERM BENEFIT OF NEMATODE CONTROL

ON YIELD OF SUGARCANE

Cadet, P¹ and Spaull, VW²

¹IRD/²SASA Experiment Station, Private Bag X02, Mount Edgecombe 4300, South Africa

Abstract

The effect of treatment with a nematicide on sugarcane yields was studied in the plant crop and 4 or 5 ratoon crops in two variety-x-nematicide trials located on similar sandy soils in the same area in KwaZulu Natal. Treatments comprised aldicarb at 3kg/ha and an untreated control. Each crop was harvested at approximately 12 months. There was a total of 10 varieties in the two trials with varieties N12 and N16 common to both. The plant parasitic nematode communities were similar except that root-knot nematodes (Meloidogyne spp) were absent from one site. Annual losses were similar over successive crops, which meant that, with the declining ratoon cane yields, proportionally greater losses occurred with time. Comparison of the two sites showed that, over a 4-year period, Meloidogyne alone was responsible for 30 % of the losses, equivalent to 15 t cane/ha/annum. The long term effect of nematodes on sugarcane production was measured after calculating a logarithmic function from the observed yields of successive ratoons. Without a nematicide the time taken for the yield to decline to a threshold of 40 t cane/ha/annum ranged from 1 year, for N27 in the Meloidogyne infested site, to 9 years, for NCo376 in the other site. Treatment with a nematicide increased this period considerably. Thus for N23 it took a projected 55 years before the yield reached the threshold on the site without Meloidogyne and 20 years for N16 on the other site. Meloidogyne was responsible for about 50% of the loss in sustainability. Differences between varieties in the rate at which ratoon yields declined meant that, over time, the best varieties at both sites were not the ones which gave the greatest annual yields during the first few crops after planting. The results clearly show that the problem from nematodes is much more serious than previously thought.

CFD MODELLING OF A RAPIDORR 444 CLARIFIER: RECENT PROGRESS

S Chetty and SB Davis

schetty@smri.org sbdavis@smri.org

Sugar Milling Research Institute, University of Natal, Durban, 4041

Abstract

Previous computational fluid dynamics (CFD) work in clarifier modelling by the SMRI was extended. The input parameters to the CFD model particularly juice and mud densities, were calculated over an entire season. The two dimensional model was adjusted and extended to a more realistic three-dimensional model of the Rapidorr clarifier. Factory tracer testing validated both 2D and 3D models. The average residence times from the tracer test output were used to determine flow to the simulated compartment. The results showed that the three dimensional model was more accurate but at the cost of increased computational time. Operational changes were investigated; particularly the influence of increased throughput on carry-over. It was determined that even at 50% higher throughput, only slight increases in carry-over were experienced, once steady state was reached, confirming the robust nature of the Rapidorr. Possible improvements to the Rapidorr would be to remove regions of re-circulation identified by both CFD models and thus reduce juice residence time. However, it was shown that lower residence time must be traded off against carry-over. Hence structural modifications were tested and evaluated in terms of the diameter of the smallest particle that settled out at progressively lower residence times.

STIMULO-DETERRENT DIVERSION, ELDANA SACCHARINA WALKER (LEPIDOPTERA: PYRALIDAE) AND XANTHOPIMPLA STEMMATOR THUNBERG (HYMENOPTERA: ICHNEUMONIDAE), PRELIMINARY RESULTS.

D.E. Conlong¹ and B. Kasl²

¹ South African Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300. South Africa.

²Ecophysiological Studies Research Program, Department of Zoology, University of the Witwatersrand, Johannesburg. South Africa.

Abstract

Plant species emit specific semiochemicals when attacked by insects. These make plants unpalatable or repellant to herbivores, and/or attract natural enemies of herbivores attacking the plant. It is hypothesized that sugarcane, because of selection for higher sucrose, has had its semiochemical production ability bred out of modern varieties. This may explain why no parasitoids are found attacking Eldana saccharina in sugarcane, while they are commonly found on it in adjacent indigenous host plants. Some plants emit these semiochemicals as natural metabolic by-products. Preliminary work on attractant properties of indigenous grass and legume species on a pupal parasitoid of E. saccharina has been completed. In olfactometer trials, Xanthopimpla stemmator was attracted to Melinis repens and the South African variety of M. minutiflora in preference to sugarcane. In cage trials, X. stemmator parasitism (%) was higher on E. saccharina pupae when sugarcane was in association with South African (21%) and Kenyan (33%) M. minutiflora, M. nerviglumis (19%) and Desmodium uncinatum (17%) compared to pure sugarcane (14%).

Research is continuing on these plants effects on other indigenous parasitoids, and into the creation of an sugarcane agroecosystem incorporating these plants, thereby reducing E. saccharina populations with no reduction in sugarcane yield.

ELDANA SACCHARINA WALKER (LEPIDOPTERA: PYRALIDAE) AND ITS PARASITOIDS AT KINYARA SUGAR WORKS, UGANDA.

D.E. Conlong¹ and A. Mugalula²

¹SASA Experiment Station, Private Bag X02, Mt Edgecombe, KZN 4300

²Kinyara Sugar Works, Masindi, Uganda).

Abstract

Since 1996, regular surveys have been completed for Eldana saccharina and parasitoids of its different life stages in sugarcane and Cyperus papyrus at Kinyara Sugar Works, Uganda. A complex of Dipteran (Tachinidae) and Hymenopteran (Braconidae, Ichneumonidae, Bethylidae and Chalcidae) parasitoids have been discovered attacking E. saccharina infesting C. papyrus. Three species of Tachinidae and one species of Ichneumonidae have been recorded from E. saccharina attacking very old sugarcane on the estate.

This paper lists the parasitoids of E. saccharina found on the estate, and follows the rates of parasitism through the seasons on populations of E. saccharina in selected C. papyrus wetlands on the estate. The population fluctuations of E. saccharina in selected sugarcane fields is also presented. Co-operation between SASEX and Kinyara Sugar Works will benefit both institutions.

A – MOLASSES CLASSIFICATION AT GLEDHOW

¹ N.Dairam and ² P.Sahadeo

¹Illovo Sugar – Gledhow ² Sugar Milling Research Institute – Durban

Abstract

Due to the South African customer demands, the refined sugar specification has gradually, over the years, been reduced from 80 to the current limit of 45 ICUMSA units. This has had an impact on the Gledhow refinery, which has limited potential for colour removal with the present decolourisation process. In order to achieve the current refined sugar colour specification, the refinery has had to operate with lower raw sugar colours at the expense of lower A – massecuite exhaustions. To overcome these problems, the option of A – molasses classification was investigated at Gledhow. The results of these tests are presented together with a history of the modifications and sampling procedures made to optimise performance. Tests have shown a gain of about 4 units of A – massecuite exhaustion, resulting in an increase in recovery of approximately 0.5% with molasses classification.

ENERGY EXPENDITURE AND ECONOMY OF MOVEMENT OF SUGARCANE CUTTERS ON BURNT AND GREEN CANE

M de L Smit, MF Coetsee, and SEH Davies

Department of Human Movement Science, University of Zululand, KwaDlangezwa, South Africa.

Purpose The purpose of this study was to investigate differences in the energy expenditure and economy of movement of sugar cane cutters with regards to burnt and green cane in situ.

Object The main objective of this study was to investigate the differences in physiological responses (VO₂, HR, EE) and the economy of movement with regards to burnt and green cane during a normal working day. The secondary object was to investigate the effect of the long and the short handle curved blade knives on the cane cutter’s energy expenditure and economy of movement.

Method Fifteen male professional cane cutters volunteered with written informed consent. Physiological parameters included oxygen consumption (VO₂) and heart rate (HR) using the portable telemetric MetaMax Ergospirometry system. Energy expenditure was calculated directly from the VO₂. During work data was collected over a 20 minute-period for burnt and green cane. Economy of movement was determined through observation of the amount of cane cut (kg.min^-1), energy expenditure per 1 kg of cut cane (kJ.kg^-1), amount of cut cane per 1 L O₂ (kg.1 L O₂), number of cane cutting strokes per minute and number of stalks per stroke. Perceptional responses were measure by means of the Universal RPE Scale.

Results The average relative O₂ consumption for cutting burnt cane (29.85 + 7.88 ml.kg.min^-1) and the calculated relative energy expenditure (0.63 + 0.17 kJ.kg^-1.min^-1) were both significantly lower than for green cane (33.42 + 5.74 ml.kg^-1.min^-1) and (0.70 + 0.12 kJ.kg^-1.min^-1, respectively. Average HR during work was not significant for burnt (119.8 + 18.61 beats.min^-1) or green (123.67 + 13.23 61 beats.min^-1) cane, neither was the maximal HR. Rate of productivity for burnt cane (30.3 + 11.52 kg. min^-1) was significantly higher than for green cane (22.98 + 5.86 kg. min^-1). Energy per kilogram required for cut cane was significantly lower (1.51 + 0.58 kJ.kg^-1) than for green cane (2.12 + 0.61 kJ.kg^-1). The amount of cane cut per litre of oxygen consumed for burnt cane (16.43 + 8.61 + 8.61 kg.1LO₂^-1) was significantly higher than for green cane (10.62 + 2.79 kg.1LO₂^-1). The number of cane cutting strokes per minute for green cane (25.45 + 3.3) was significantly lower than for burnt cane (34.42 + 6.87). The amount of stalks cut per stroke of green cane (2.55 + 0.49) was significantly higher than for burnt cane (2.45 + 0.37). The secondary study produced no significant difference in physiological parameters measured variables for the long handled knife (10.58 + 1.21) with the short handle knife (11.71 + 1.8), with the exception of the cane cutter’s perceived exertion (RPE).

Conclusion Results revealed that cutting burnt cane surpasses all aspects of harvesting with regard to physiological parameters and the economy of movement. The choice in knives depends on the preference of the cane cutter, as there were no significant difference.

OPERATION AND PERFORMANCE OF THE GRANULAR ACTIVATED CARBON PLANT AT NCHALO

McLean Debwe (Illovo-Malawi)

Henry Kamanga (Illovo-Malawi)

Anthony Kostopolous (Vivend Water-RSA)

Abstract

Nchalo mill used to have a phosphatation/sulphitation back-end refinery. To improve the quality of its refined sugar, a full scale granular activated carbon plant was installed during the 1999-2000 off-crop as a replacement of the sulphitation process. A carbon reactivation kiln was also installed This paper describes the performance of the granular activated carbon plant and the reactivation kiln over its first season of operation.

The decolorising plant has 6 carbon columns and it operates with 3 in parallel lead and 2 in parallel polishing modes. The 6^th column is under reactivation or on standby. Daily composite samples were taken off the feed, intermediate and product lines and analysed for color. The pH of the filtered and decolorised liquors was also measured. Each batch of carbon was analysed for iodine number and ash after reactivation. A maximum pH drop of 0.4 units across the column was recorded and an average of 67 % color removal was achieved. An average sugar color of 55 icumsa units was obtained in a three boiling system. Reactivation produced carbon with an average iodine number of 894 at a carbon usage of 0.12 kg per ton.

ACCIDENTLY INTRODUCED EXOTIC EARTHWORM SPECIES DOMINATE IN SOILS ON SUGARCANE ESTATES IN THE ESHOWE AREA OF THE NORTH COAST

T.C. Dhlamini¹, R.J. Haynes¹ and R. Van Antwerpen ²

¹ School of Applied Environmental Science, University of Natal, Pietermaritzburg, Private Bag X01, Scottsville, 3209.

² South African Sugar Association Experimental Station, Private Bag X02, Mount Edgecombe, 4300.

Abstract

The effects of land management including sugarcane, horticultural crops (citrus, avocado and banana), forestry (gum, wattle and pine), kikuyu pasture, native forest and native grassland on the size and composition of the earthworm community on sugarcane estates in Northern KwaZulu-Natal was investigated. Earthworm numbers followed the order: burnt sugarcane < trashed sugarcane = grassveld = gum forest = pine forest = wattle forest = avocado orchard < citrus orchard < banana plantation < native forest < kikuyu pasture. The pattern of change in organic C, and particularly microbial biomass C, with land-use showed broadly similar trends to those of earthworm numbers. This demonstrates that the C input to the soil and the amount of labile, metabolizable C present are the major determining factors to the size of both the soil microbial and earthworm communities.

Over 80 % of the earthworms identified were exotic species which are believed to have been accidently introduced from India. The most numerous earthworm was Pontoscolex corethrurus which is a soil dwelling(endogeic) species. The predominant litter dwelling (epigeic)species was Amynthas rodericencis which was particularly numerous under avocado, native and gum forest and banana. P. corethrurus was the dominant species in sugarcane fields. Earthworms were found to be much more prevalent in the cane rows than between them and they were generally associated with sugarcane roots. Compared with burning , earthworm numbers were more than twice as high under green cane harvesting with trash retention.

LONG-TERM EFFECT OF SUGARCANE PRODUCTION ON SOIL QUALITY ON THE

SOUTH COAST AND MIDLANDS OF KWAZULU-NATAL

C.S. Dominy¹, R.J. Haynes¹ and R. van Antwerpen²

¹ School of Applied Environmental Science, University of Natal, Pietermaritzburg, Private Bag X01 Scottsville, 3209.

² South African Sugar Association Experimental Station, Private Bag X02 Mount Edgecombe, 4300.

Abstract

The effects on soil condition of increasing periods under intense sugarcane production on a Glen Rosa Soil on the south coast and a Hutton soil in the Midlands was investigated. Soil organic C content in the 0 -10 cm layer was about 4.6 % under veld at both sites. On the Hutton soil, where sugarcane production had continued for only about 30 years, soil organic C content had declined to about 3.5%; the corresponding value at the Glen Rosa site was about 1.8 %. The higher organic matter content at the Hutton site was attributed to clay-protection of organic matter in this soil. At the Glen Rosa site, organic C declined exponentially and reached a new equilibrium level of about 1.5 % after 40 - 80 years of sugarcane production.

The loss of soil organic matter resulted in a concomitant decline in readily mineralizable N, soil microbial biomass C, soil microbial activity as measured by respiratory rate and fluorescein diacetate hydrolytic activity and soil aggregate stability. The decline in microbial biomass C, was much more rapid and pronounced than that for organic C indicating a preferential loss of the labile organic matter fraction under continuous sugarcane production. It was concluded that the loss of soil organic matter content under long-term sugarcane production is pronounced and that there is considerable scope to promote practices that add organic residues to the soil (e.g. green cane harvesting) in order to improve soil quality.

A REVIEW OF MAPPING AND GEOGRAPHIC INFORMATION SYSTEMS WITHIN THE SOUTH AFRICAN SUGAR INDUSTRY

C Gers¹, D Erasmus²

¹South African Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300, South Africa

²Geographic Information Management Systems, 2nd Floor Merthyr, 49 Kings Road, Pinetown, 3600, South Africa

Historically, mapping of the industry was co-ordinated centrally by the regulated sugar industry in the form of quota maps. Following deregulation of the industry co-ordinated mapping initiatives fell away, resulting in the dissemination of mapping and geographic information system responsibilities to individual mill group boards. This paper reviews the status of mapping and information systems across the industry and proposes a framework for consolidating the initiatives of the individual mill group boards into a single system.

SPOT 4XI SATELLITE IMAGERY FOR MONITORING SMALLHOLDER AREAS IN UMFOLOZI, SOUTH AFRICA

C Gers

South African Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300, South Africa

This paper presents the use of time step Spot 4Xi imagery to determine the sugarcane crop areas of smallholder growers in a selected area within the Umfolozi mill supply area. This was achieved by manipulation of the four satellite-measured bands and subsequent classification of sugarcane into harvested and non-harvested areas. Preliminary results indicate that the satellite imagery classifications are able to clearly distinguish between planted sugarcane and harvested plots.

(POSTER)

INTEGRATED CONTROL OF THE SPOTTED STALK BORER CHILO SACCHARIPHAGUS BOJER (LEPIDOPTERA, PYRALIDAE)

IN REUNION ISLAND.

R. Goebel ^1,2, J. Rochat ¹, E. Tabone ³, J.M. Bègue ¹, E. Fernandez ¹,

R. Tibère ¹, J.C. Gauvin ¹, B. Vercambre ⁴.

(1: CIRAD, Reunion, France; 2: SASEX, Mount Edgecombe, South Africa;

3: INRA, Antibes, France; 4: CIRAD, Montpellier, France)

Abstract

The stalk borer, Chilo sacchariphagus Bojer is a major pest of sugarcane in Reunion and Mauritius. The Entomology Laboratory of CIRAD, which has worked for nearly 30 years on insects pests including stem borers, has focused its research program on the control of this borer since 1994.

Its population dynamics in relation to varieties, cultural practices and climate has been examined for 4 consecutive years in all the sugarcane areas.

Field trials confirmed that R 579 is more susceptible to C. sacchariphagus than the more common variety R 570 planted in Reunion. Various aspects of resistance (antibiosis, antixenosis, penetrometry of the stalks…) have been investigated. Resistance may be partly due to mechanical properties of the cane, but the mechanisms of resistance are not really known.

The impact of predators, predominantly ants, on borer egg masses was quantified. It is believed that the burning practice has negative effect on natural enemies. This has been demonstrated in field that when burning was banned, natural enemy populations increased and damage due to borers was lower.

C. sacchariphagus and Galleria mellonella eggs are used to trap egg-parasitoids in the field to identify the parasitoids and examine their population dynamics. Natural parasitism of borer eggs is about 30–40%. To date, a single species, Trichogramma chilonis, has been recovered in sugarcane fields in Reunion. Bionomics of the species and/or strains of Trichogramma collected in the fields are examined in the laboratory to select appropriate strains for mass production and augmentative release programs. Field experiments with inundative releases of Trichogramma are planned to test for their efficacy.

Biological control of the sugarCANE stem borer Chilo sacchariphagus (Lep : pyralidae) in Réunion Island : new researches and perspective with the use of egg parasitoid Trichogramma chilonis Ishii (Hym. : trichogrammatidae).

Régis Goebel¹, Elisabeth Tabone², Jacques Rochat³& E.Fernandez³.

¹ SASEX/CIRAD, Entomology Department, Mount Edgecombe 4300, South Africa

² INRA, Entomologie et Lutte biologique, 1382 route de Biot, 06560 Valbonne, France

³CIRAD, laboratoire d’entomologie, 97408 Saint-Denis messageries, cedex 9, île de Réunion, France

Abstract

One of the most serious insects pests of sugarcane in Reunion Island is the spotted stem borer Chilo sacchariphagus Bojer. Collaborative work between CIRAD and INRA has led a biological control programme with the use of Trichogramma chilonis Ishii, an effective egg parasitoid.

From experiences where biological control with exotic parasitoids has failed, the importance of indigenous parasitoids and their impact on the populations of C. sacchariphagus in the field has been implicated. Recent observations confirm the key role of Trichogramma in biological control but parasitism levels appear to decline in areas where cane is burnt at harvest.

Current research including morphological and biological studies on this parasitoid are presented in the perpective of inundative releases in sugarcane.

LAND FORMING ON FLAT CLAY SOILS OR IMPROVED SUGAR CANE YIELDS

* J M Gosnell ¹ and J W Hester²

¹PGBI International, 8 Wolseley St., Woodmead 2128, pgbi@pixie.co.za

²John W Hester and Associates, Shelby, Mississippi, USA

* To whom enquiries should be addressed

The Problem: Surface drainage is often a problem on heavy black montmorillonitic clays with very flat grades and is typical of several Mozambican deltas where sugarcane is grown under high rainfall conditions. Widespread ponding of surface water can cause substantial reduction in cane growth often resulting in yields of 60 – 70 tons cane/ha, far below expected yield levels.

What is Land forming?: Land forming is the process of creating grades, typically around 1:1000, which allow water from either rainfall or irrigation to run off the field within 24 hours. This must also be backed up by good tertiary, secondary and primary drains and drain-pumping where required, if the full benefit of the investment is to be derived.

How is it done?: A detailed field survey is carried out with a Total Station, followed by the use of laser-controlled tandem carry-all and ejector scrapers towed by large 4WD tractors with dual wheels, followed by land planing. Specialised proprietary computer software, with three optional modes, optimizes cut-and-fill soil volumes; this minimizes not only costs, but also the risk of “scalping” into the subsoil. Typical volumes of soil moved range from 500 to 700 m³/ha, depending on the topography.

Irrigation: Following land forming, surface irrigation is used as water penetration is better on these self-mulching cracking clays than with overhead irrigation. Capital cost of overhead systems, as well as unreliable and expensive power, also militate against the latter.

Benefits: The application of these principles has enabled farmers in the Ord, Western Australia, to achieve consistent yields of 130 to 150 tons cane/ha on very flat heavy clay soils using furrow irrigation making the investment well worthwhile.

References: PGBI International pioneered laser-controlled land forming on heavy black montmorillonitic clays in Mozambique this year. Initial indications are encouraging – detailed performance of the fields will be available early next year after the first crop.

LONG-TERM EFFECT OF GREEN CANE HARVESTING VERSUS BURNING ON THE SIZE AND DIVERSITY OF THE SOIL MICROBIAL COMMUNITY

M.H. Graham¹, R.J. Haynes¹, L. Zelles² and J.H. Meyer³.

¹ School of Applied Environmental Science, University of Natal, Pietermarizburg, Private Bag X01 Scottsville, 3209.

² GSF-National Research Institute Centre for Environmental Health, Institute of Soil Ecology, Ingolsträdter Landstrass 1, D-85764 Neuherberg, Germany.

³ South African Sugar Association Experimental Station, Private Bag X02 Mount Edgecombe, 4300.

The long-term effects of green cane harvesting with trash retention, compared with burning, on soil microbiological aspects were evaluated using data from the long-term trash management trial at Mount Edgecombe (BT1). Total organic C content was greater under green cane harvesting than burning in the surface 0 - 10 cm layer of soil. Microbial biomass C was greater under green cane harvesting than burning to a depth of 30 cm. Both K₂SO₄-extractable C and light fraction C were also increased markedly by trash retention to a depth of 30 cm reflecting the downward leaching of soluble C from the trash blanket. This demonstrates the value of these labile C fractions as indicators of changes in soil C. Soil community structure was examined based on extraction and identification of phospholipid fatty acids (PLFA). Data from PLFA composition of soils were subjected to principal component analysis which accounted for over 78% of the total variance. Trash retention markedly changed the composition of the microbial community compared with burning. Fertilizer applications had very little effect on the community composition in the burnt treatments but changed the community greatly where trash was returned. The total quantity of PLFAs extracted was greater from trashed than burnt treatments reflecting the larger microbial biomass under trash retention. Principal component analysis was also used to separate PLFA profiles from soils under long-term burnt sugarcane, maize , annual ryegrass, kikuyu grass and undisturbed veld. Results clearly showed that community composition under sugarcane was very different from that under the other land management practices.

IRRIGATION SYSTEM EVALUATION

Brent Griffiths and Neil Lecler

Zimbabwe Sugar Association Experiment Station

Private Bag 7006, Chiredzi, Zimbabwe

(Email zsaes@zol.co.zw)

The sugar industry in Zimbabwe has established a Mobile Irrigation Performance Evaluation Unit (MIPU) in order to assess the design and operational performance of irrigation systems. The evaluation procedures for: sprinkler, centre pivot, micro and furrow irrigation systems are outlined in this paper. Analysis of the field measured values enables the performance of the system to be assessed, and remedial measures for either design, maintenance, or management are prescribed where necessary. The potential contribution to furrow irrigation design and management afforded by the application of simulation software in order to predict performance is discussed. The correct application of these furrow irrigation simulation tools can facilitate the design or modification of furrow irrigation layouts so that performance is comparable to more marketed irrigation systems.

Results from the analysis of drip systems show:

· incorrect filtration and system pressures,

· adequate performance of the floppy sprinklers when designs meet appropriate specifications.

An effort to translate irrigation system performance measures to associated water and crop yield implications has shown the significant costs associated with poor irrigation system performance. Although field measurements are often relatively simple the benefit of having the MIPU as part of an independent irrigation advisory service to do a thorough interpretation of proposed and/or existing systems, can often be shown to be significant.

MANIPULATING SUCROSE METABOLISM WITH A SINGLE ENZYME: PYROPHOSPHATE-DEPENDENT PHOSPHOFRUKTOKINASE (PFP)

J-H Groenewald and FC Botha

Institute for Plant Biotechnology, University of Stellenbosch, Private Bag X1, Matieland, 7602

(Short Communication)

PFP catalyses the reversible conversion of fructose 6-phosphate (F6P) to fructose 1,6-bisphosphate (Fru-1,6-P₂). This conversion can be seen as the watershed between sucrose and fibre synthesis on the one hand and respiration, protein synthesis and secondary metabolism on the other. As such, the enzyme probably plays an important role in regulating carbon partitioning, and therefore sucrose levels, in sugarcane. Consistent with this hypothesis, the activity of PFP in sugarcane decreases with culm maturity, and varies between varieties differing in their sucrose storage capacity. Moreover, PFP activity is inversely correlated with sucrose content across both commercial varieties and a segregating F1 population. The only way in which to confirm the role of PFP in sucrose metabolism in sugarcane is to manipulate its activity in transgenic plants. We down regulated PFP activity in sugarcane using co-suppression technologies and up regulated the activity through the expression of exogenous PFP genes. Transgenic plants growing under glasshouse conditions expressed the specific transgenes and had varying levels of PFP activity. The influences these changes on carbon metabolism will be discussed.

This work was supported by the South African Sugar Industry and the Department of Trade and Industry.

PATHOGEN AND PEST INDUCED GENE EXPRESSION IN SUGARCANE (SACCHARUM SPP.). INTEGRATING A PROGRAMME FOR MARKER DISCOVERY AND GENE ISOLATION (SHORT COMMUNICATION)

Heinze B.S., Thokoane L.N., Barnes J.M. and Rutherford R.S.

Biotechnology Department

South African Sugar Association Experiment Station

Private Bag X02

Mount Edgecombe, 4300

Abstract

SMART (Switching Mechanism At 5' end of RNA Transcript) full-length cDNA synthesis followed by Suppression Subtractive Hybridisation or cDNA-AFLP is being used to detect sugarcane differential gene expression in response to challenge by pathogens (Ustilago scitaminea H. & P. Sydow and Sugarcane Mosaic Virus) and the insect pest Eldana saccharina Walker (Lepidoptera: Pyralidae). Differentially expressed sequences receiving putative identities following database searches (http://www.ncbi.nlm.nih.gov/blast/blast.cgi) are employed as RFLP probes. Candidate genes for resistance are identified via polymorphisms generated across 78 phenotypically well characterised varieties and the AA40 genomic mapping population. For example, a fragment identified as a phenylpropanoid-flavonoid pathway transcription factor generated a RFLP which significantly associates with smut resistance rating (t-test: p = 0.002; r² = 0.202). The rapid isolation of full-length coding sequences, without the use of cDNA libraries, for two phenylpropanoid-flavonoid pathway transcription factors and two PR5 anti-fungal proteins is described. Full-length coding sequences of candidate genes are utilised in the Biotechnology department’s transgenic programme.

CHEMICAL FLOWER SUPPRESSION USING ETHREL ETHEPON 48%)

ON SUGAR CANE GROWN ON THE NATAL SOUTH COAST

Malcolm Humm

FARM SERVE

P. O. Box 700, Umtentweni, 4235

Tel / Fax : 039 - 6950730

E - Mail : fmserve@yebo.co.za

Abstract

During the seasons between 1998 and 2000, profuse flowering in sugar cane grown on the Natal South Coast was experienced three years in a row compared with the accepted norm of one year in five.

The time of floral induction was determined at between March 8th and March 30th. (1. personal communication). A series of field scale trials were carried out during February of 1998, 1999 and 2000 on two large estates in the Scottburgh area to determine the efficacy of a single application of Ethrel (ethepon 48 %) in suppressing bud initiation in varieties NCo376, N12, and 805 growing in a number of different soils and aspects. The age of the sugar cane at the time of spraying was between three and five months.

During February 2000, a further six farms were selected for trials on farms near Umkomaas, Hibberdene, Umzumbe and Port Shepstone, the varieties tested being NCo376 and N12. The sugar cane was between three and six months old at the time of spraying.

In all the trials, the degree of flower suppression achieved was between 80 - 100 %. This was determined during the 2000 trials by local pest and disease inspectors.

Treated sugar cane that either did not flower at all or where the percentage of flowered stalks was below 20 % was in a suitable condition to carry over to the following season.

More definitive trials will be carried out during February 2001 to more accurately determine the time of floral induction, the optimum time to apply the Ethrel to achieve maximum flower suppression and the correct rates of Ethrel to use on the different varieties in question, which will include the new varieties N27 and N29 which are inclined to flower profusely.

Key words : Ethrel, flower suppression, Natal South Coast and carry over.

ENVIRONMENTAL IMPLICATIONS OF USING BAGASSE-DERIVED ETHANOL

AS A GASOLINE OXYGENATE IN INDIA

Kiran L. Kadam

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, Colorado, U.S.A.

Bagasse, the fibrous residue generated during sugar production from sugarcane, can be a desirable feedstock for fuel-grade ethanol production. Maharashtra state is the second largest sugarcane producing state in India with an annual cane production of 40–45 million tonnes; it is, however, the largest in sugar production with an annual sugar recovery of 11 million tonnes. Based on this large sugar production capacity, enough bagasse is available in Maharashtra for a potential ethanol plant. The study objective was to conduct a Life Cycle Assessment (LCA) to quantify the environmental benefits of using bagasse-derived ethanol from such a plant, the ethanol being used to make an E10 fuel blend. Environmental flows were compared for two cases: burning excess bagasse as a disposal option (Scenario 1) and conversion to ethanol (Scenario 2). In terms of local air quality, lower net values for Scenario 2 are observed for the following emissions: CO, hydrocarbons (except methane), SO_x and NO_x, and particulate matter. Scenario 2 also consumes less fossil energy and reduces carbon dioxide and methane emissions, leading to a concomitantly lower greenhouse potential. Given that India is a developing country, the lower greenhouse potential is a particularly desirable attribute for Joint Implementation (JI) and Clean Development Mechanism (CDM). JI and CDM initiatives are avenues specified under the Kyoto Protocol that can help deploy the ethanol production scenario. Details of the LCA results and policy implications will be discussed.

REFERENCE EVAPORATION ESTIMATES IN THE LOWVELD OF ZIMBABWE

Neil Lecler

Zimbabwe Sugar Association Experiment Station Private Bag 7006, Chiredzi, Zimbabwe

Abstract

In the south east lowveld of Zimbabwe, most of the research involving sugarcane crop water use has been undertaken using the evaporation from United States Weather Bureau (USWB) Class A evaporation pans as the reference evaporation estimate. World wide research studies show, however, that the correlation between the evaporation from an A-pan and the evaporation from a cropped surface can be markedly different in summer and inter and also under advective conditions or when there are wide variations in wind and humidity. The use of a more representative reference evaporation than the A-pan, such as that defined by the Food and Agricultural Organisation which is based on the Penman Monteith equation, may, therefore, result in gains in irrigation water use efficiency. For this reason, relationships between: - the FAO Penman Monteith reference evaporation, evaporation from a class A-pan, and - evaporation from a relatively simple commercially available atmometer device that has been designed to mimic many of the evaporation characteristics of a plant, have been investigated. In this paper, comparisons between these three reference evaporation estimates are presented. The comparisons were based on: 33 years of daily weather data collected at a manual weather station, two years of data from an automatic weather station and one years data from the atmometer device, all stationed at the Zimbabwe Sugar Association Experiment Station. The implications of the results for irrigation water management are discussed.

INITIAL FIELD TESTING OF TRANSGENIC GLUFOSINATE-AMMONIUM RESISTANT SUGARCANE

N B Leibbrandt

South African Sugar Association Experiment Station, Private bag X02, Mount Edgecombe, 4300

The South African Sugar Industry has recognised certain benefits in using genetically transformed sugarcane. Herbicide resistance is seen as a major advantage and variety NCo310 has been genetically modified for tolerance to the herbicide Buster (glufosinate – ammonium 200g a.i./L). Under semi-controlled conditions, young transgenic sugarcane plants were asymptomatic when sprayed with up to 7L/ha of Buster, while non-transformed plants were killed at 4L product per hectare. A field trial to assess possible physiological differences between transformed and non-transformed sugarcane, and to compare different Buster applications was established. This trial included a plant and first ratoon crop. Buster was either used alone as a repeated chemical hoe application, or in conjunction with pre-emerge products. Further treatments included an industry standard programme without Buster, and handweeded control. The transformed sugarcane expressed complete tolerance to Buster, while phytotoxicity in the non-transformed cane was severe. Due to weed competition, yields for handweeding and Buster alone treatments were inferior to that of treatments that included pre-emerge herbicides. Results also confirmed the economic advantages of early weed control, and it is therefore unlikely that in the future, only one product be recommended for use in herbicide resistant plant cane. Yields for non-Buster treatments were statistically higher in non-transformed cane which suggests some other physiological difference may have resulted during transformation.

SEVENTY-FIFTH ANNUAL REVIEW OF THE MILLING SEASON

IN SOUTHERN AFRICA (1999-2000)

GRE Lionnet

Sugar Milling Research Institute, University of Natal, Durban 4001

Abstract

Performance, throughput and other relevant aspects of the sugar industries in Southern Africa are presented, compared and discussed. Data from South Africa, Malawi, Swaziland and Zimbabwe have been used; in addition some results from Mauritius and from Reunion have been included. The cane crop, factory performance and sugar quality are discussed in some detail. Generally, the season in South Africa has been a good one.

A SWAZI APPROACH TO SUSTAINABLE SOCIO‑AGRICULTURAL DEVELOPMENT: THE KOMATI DOWNSTREAM DEVELOPMENT PROJECT

Keywords: Training, Empowerment, Sustainable, Development, Sugarcane,

Swaziland

Abstract:

The Komati Downstream Development Project (KDDP) is a new and progressive irrigated agricultural scheme whose primary objectives are 1) to alleviate poverty, and 2) to empower local communities through grassroots development of irrigated smallholder sugarcane and assorted crop farms. The project was initiated by the Government of Swaziland in an effort to improve the standards of living for the 22,000 people who comprise the rural subsistence communities in the northeastern lowveld region of the country. The project site lies in the Komati River Basin, which extends over 27,000 hectares, and the KDDP includes the development of 6,000 hectares. The government created a national organization called the Swaziland Komati Project Enterprise (SKPE) to facilitate the development of the project, which began in 1999, and is expected to be complete by 2006.

The project philosophy is based on farming and growth through training, knowledge and empowerment. SKPE?s role is to facilitate the project and offer resources to the communities which allow the communities themselves to manage the direction, speed and success of the project. In addition to, and as a result of, the development of irrigated sugar farms, the project goals encourage the creation of a local and diverse small‑business sector to accommodate the increase in potentially successful capital markets. The project begins with the development of sugar farms, evolves into the development of economically sustainable communities and ultimately stands as an independent region of the country managed by local communities as a model of social, environmental and economic success.

CHARACTERISING FUELS FOR BIOMASS – COAL FIRED COGENERATION

N. MAGASINER ¹, C. van ALPHEN ², M. INKSON ³, B. MISPLON ⁴

1. Thermal Energy Systems cc Cape Town

2. Van Alphen Consultancy, Johannesburg

3. Biotherm Ltd, London

4. Thermal Energy Systems cc Cape Town

Coal is commonly used as an auxiliary fuel in biomass fired co-generation power stations. Design of the boilers for these stations therefore requires a detailed knowledge of the properties of the biomass, the coal and any interaction between the two.

A continuous ash discharge (CAD) stoker is normally used for this combination of fuels. In assessing an acceptable grate rating for biomass fuel firing, the effective moisture of the biomass is the key parameter required whilst the grate rating for coal is a function of its reactivity.

The GCV of biomass fuels has been characterised as a formula involving their moisture and ash contents. In the case of bagasse, the values of the constants have been sufficiently defined to avoid the need to measure its GCV empirically. To size the grate for biomass fuel firing the concept of ‘effective’ moisture has to be introduced to overcome the distortion caused by any variation in ash content.

There are sophisticated methods of analysing coal to establish reactivity but the methods are time consuming and only a few laboratories are equipped to use them. A new approach is proposed to use the petrography of the coal to predict reactivity, microscopically examining the coal to examine the make-up of its organic constituents [the ‘macerals’] and hence determine its characteristics. The technique is fast and relatively inexpensive and where it has been used recently has yielded commercially viable results.

The techniques described allow the grate to be designed for optimum combustion but do not predict how the ash chemistry of the fuels may adversely affect the anticipated results. Furthermore they do not predict any interaction between the fuels which may preclude combination firing. An appropriately designed grate will help resolve differing primary air and ash discharge requirements. The characteristics of the two ashes, however, must be brought to account by means of specialist phase diagrams in order to determine whether the grate and/or furnace will need to be de-rated to prevent clinker and slag formation and boiler fouling.

ENVIRONMENTAL PRESSURES, CHALLENGES AND STRATEGY

FOR THE SUGAR INDUSTRY IN SOUTH AFRICA

G.W. Maher

South African Sugar Association Experiment Station Mount Edgecombe

Abstract

The cane growing industry in South Africa is increasingly coming under pressure due to environmental issues, especially where cane fields border onto housing developments and prime tourist destinations. An overview is provided of some of the environmental pressures associated with the production of sugarcane. The environmental pressures recognised as being of greatest concern are identified and discussed. A possible environmental strategy for the sugar industry is described.

TEMPERATURE TOLERANCES OF STURMIOPSIS PARASITICA CURRAN (DIPTERA: TACHINIDAE)

A.J. Martin^1,2, D.E. Conlong¹ and R. Slotow²

¹South African Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300, ²School of Life and Environmental Sciences, University of Natal, Durban, 4000

The effects of temperature on developmental rate of Sturmiopsis parasitica was investigated under controlled laboratory conditions. S. parasitica immature life stages were exposed to E. saccharina larvae at constant temperatures of 10, 18.2, 22.1, 25, 30.9 and 35.9 °C. Maggots, and subsequently pupae of S. parasitica did not survive at 10 °C and 35.9 °C. No pupal emergence occurred at 18.2 °C. Development rate increased significantly with increasing temperature for both maggot and pupal stages. Estimated lower development thresholds for maggot and pupal stages were 12.8 and 17.4 °C respectively. Day degrees were 230.7 ± 5.3 and 157.9 ± 5.2 for the maggot and pupal stage respectively. An average of 388.6 day degrees are required to complete development to adulthood. There was no significant effect of temperature (between 25.0 and 30.9 °C) on adult longevity. Because some areas in the South African sugar belt experience average winter temperatures below the lower development threshold (17.4 °C) of S. parasitica, potential release sites are limited to the Kwazulu-Natal coast, Swaziland and eastern Mpumulanga.

THE USE OF TISSUE BLOTS TO SCREEN FOR VARIETAL RESISTANCE

TO RATOON STUNTING DISEASE.

SA McFARLANE

South African Sugar Association Experiment Station, Mt Edgecombe

Abstract

Differences in varietal reactions to ratoon stunting disease (RSD) have been recognised for many years. The use of RSD resistant genotypes may offer an alternative strategy for minimizing losses due to the disease. Selection for disease resistance in most plant breeding and selection programmes is based on visual assessments of disease symptoms. Stunting is the only external symptom of RSD but this is not easily seen when all the stalks are infected and is not characteristic of RSD alone.

A number of methods have previously been used to assess varietal reactions to RSD. Most recently a modified immuno-blot assay, the tissue blot-enzyme immunoassay (TB-EIA) was developed to detect and enumerate vascular bundles colonized by Leifsonia xyli subsp xyli, the causal organism of RSD. Research in Florida indicated that in properly structured trials, it was possible to use the TB-EIA to measure both the incidence and severity of RSD, two parameters commonly regarded as being necessary to breed and select for disease resistance in sugarcane.

Preliminary experiments conducted at SASEX and presented in this poster indicate that the TB-EIA is a useful tool for distinguishing highly susceptible varieties such as N14, from those that are more tolerant.

SOME MEASUREMENTS OF MECHANICAL SUGARCANE HARVESTING EQUIPMENT

E Meyer

South African Sugar Association Experiment Station Private Bag X02, Mount Edgecombe, 4300, South Africa.

Abstract

The SASA Experiment Station, Agricultural Engineering Department conducted time and motion studies on various loading and harvesting machinery and equipment during two separate harvesting trials in Swaziland during the 1998/1999 and 2000/2001 seasons. The quality of cane delivered to the factory by the various cane handling systems as also assessed.

The results of these studies show that machinery performances vary considerably depending on cane yield as well as crop and field conditions. There was little difference in instantaneous loading rates or cane quality of the push-pile loader loading either into the “Simunye” bins or “Land train spiller trailers. The instantaneous harvesting rate of the combine harvester operating in burnt cane was some forty percent higher compared to green cane. Furthermore, the quality of cane harvested by combine harvester when operating in burnt cane was significantly better than when harvesting green cane.

SOIL DEGRADATION AS A FACTOR IN YIELD DECLINE IN THE SOUTH AFRICAN SUGAR INDUSTRY

J. H. Meyer and R. van Antwerpen.

SA Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300.

Abstract

The dimishing yield of crops after they have been under continuous cultivation for a number of years is a common feature of many crops including sugarcane. This paper reviews the subject of the yield productivity plateau in the South African Sugar Industry with reference to soil quality. The preliminary results of a three phase approach based on defining the extent of the yield plateau phenomenon, changes in soil quality under continuous cropping and solutions for breaking the effects of sugarcane monoculture are discussed. The use of soil quality indicators to quantify the effects of monocropping sugarcane on soil degradation is further advocated.

Keywords: yield decline, monoculture, soil degradation, soil quality

A REVIEW OF THE EFFECT SOIL FERTILITY AND NUTRITION ON CANE QUALITY

JH Meyer and RA Wood

Abstract

The fertility status of the soil and the standard of fertiliser management can have an important effect on the chemical composition and quality of cane juice. Both nutrient deficiency and nutrient excess can result in below optimum sucrose contents while excessive nutrient uptake may also influence the exhaustibility of final molasses and the colour and ash content of raw sugars. Juice quality parameters other than sucrose content, such as soluble high molecular weight polysaccharides can interfere with the processing of raw sugar. The level of crop nutrition may also influence the presence of such non-sucrose constituents. In this paper the results of past nutritional trials are reviewed to assess the impact of mainly nitrogen, phosphorus and potassium fertilisation on cane quality and the implications of over and under fertilisation in terms of the RV cane payment system. More than ever before, there is the need for growers to use soils and leaf analysis through FAS in order to maximise RV production.

Keywords: Nutrition, fertilisers, cane quality

A review of COMMERCIAL VARIETAL pERFORMANCE ON DIFFERENT SOILS

AT MHLUME in SWAZILAND

J. D. Ndlovu

Mhlume (Swaziland) Sugar Company, P.O. Box 1, Mhlume. L309.

Tel. 313 1211, Fax 313 1309, E-mail <JerryN@mhlume.co.sz>

Abstract

A total of 5503 field records (84071 ha) from 1988 to 1998 were analysed to determine the effects of different soils, irrigation method, varieties and harvest seasons on yield. Over this period the main varieties (95% of the estate area) were N14, N17, N19 and NCo376. The results show that soil type, irrigation method, variety and harvest seasons influenced yield and quality. The good soils (mainly R-sets or Shortlands) produced 100 TCH and 14.51 TSH which is 12% and 14% better than the poorer soils (mainly H & Z sets or Kroonstart/Sterkspruit) respectively. On average fields under furrow produced 4.5% more TCH than under sprinkler because furrow fields tend to be better in terms of slope, soil uniformity and surface drainage. There appears to be no interactive effect of soil type and furrow or sprinkler irrigation on yield. Variety N19 performed better than the other varieties under the conditions studied. N17 produced some of the highest quality cane but poor cane yields resulting in this variety being inferior to the other three. Variety N14 tended to produce higher cane yields than NCo376 but poorer quality but it is a reasonable alternative to NCo376 under good soil conditions. All varieties produced higher sugar yields in the early part of the harvest season (late April to June) than in the late season harvest period (October to mid December). An early start to the season is preferred to a late season. The extent to which this can be done would depend on a balanced trade-off between sugarcane yield and quality.

THE CONTRIBUTION OF VARIETY NCO376 TO SUGAR PRODUCTION IN SOUTH AFRICA FROM 1955 TO 2000 AND ITS VALUE AS A PARENT IN THE BREEDING PROGRAMME.

KJ Nuss

SASA Experiment Station, Private Bag X02, Mt Edgecombe.

Abstract

When NCo376 was released in 1955, it had to compete with the popular NCo310. However, its superior sucrose yield (but lower sucrose content) and wider adaptation to different growing conditions ensured that it became the major variety already in 1965. It maintained this status until its sib, N12, produced more cane than NCo376 in 1995. From 1970/71 till the 1985/86 milling seasons, NCo376 produced more than 70% of the cane delivered to the mills in South Africa. The total sugar produced by NCo376 until December 2000 amounted to about 38.9 million tons of sugar.

N12 was the first seedling of NCo376 to be released and its hardiness, drought tolerance and resistance to mosaic and smut were traits preferred by growers. Subsequent releases that are offspring of NCo376, include N16, N17, N18, N19, N20 and N23. In the season 2000/01, N12, N16, N17, N19 and N23, produced 60% of the sugar in South Africa. Some second-generation offspring of NCo376 and other NCo’s appear most promising and should become available to the industry in the next few years.

A CROP WATER USE COEFFICIENT DATA BASE FOR

PRACTICAL IRRIGATION SCHEDULING OF SUGARCANE

F Olivier, A Singels & C.N Bezuidenhout

SASEX, Agronomy Department, Private Bag X02, Mt. Edgecombe, 4300

The National Water Act aims to encourage more efficient water use in all sectors, especially irrigation, which accounts for more than 50% the country’s total water use. Approximately 20% of the 420 000 hectares currently under sugarcane in South Africa is irrigated. Irrigation scheduling will therefore play an increasingly important role to optimise the use of expensive irrigation water. Various scheduling methods are available such as (1) the direct monitoring of soil water content and the estimation of soil water content by the profit/loss approach using either (2) A-pan evaporation measurements, or (3) crop water use estimates from weather data and crop models. It has been shown that for atmospheric based methods, (3) is more accurate than (2), but also more difficult. It is therefore recommended that Penman estimates of reference cane evaporation (Eto), which are becoming increasingly available, are used with appropriate crop coefficients as an alternative to applying complicated crop models. The aim of this project was to use the Canesim crop model to generate a data base of weekly crop coefficients for all the major sugarcane irrigated areas. Representative sites with long term weather data records in the irrigated areas of Komatipoort, Malelane, Pongola and Zululand-North were selected. Different irrigation systems (flood, surface and sub-surface drip and sprinkler), row spacing and crop cycles were also included in the model runs. More than 22 000 simulation runs were executed. An Access data base was used to calculate weekly long term mean crop coefficients and standard deviations for each situation. Future work will include development of an internet based decision support program (DSP) that will allow the user to specify his location, nearest weather station, irrigation system, row spacing and starting month. The DSP will then display weekly crop coefficient values specific to that particular situation.

THE QUESTION OF TRANSFERS IN REGIONAL BREEDING AND SELECTION

RC Parfitt & DW Thomas

South African Sugar Association Experiment Station, Private Bag X02,

Mount Edgecombe 4300, South Africa

Abstract

The approach to breeding and selection followed by the South African Sugar Association is regional breeding. The production area has been divided into five regions and each region has a separate breeding and selection programme. Interchange of genetic material among programmes is possible and can be done at different stages. Historically the interchange of genetic material among programs was carried out at the final selection stage (stage 5 or secondary variety trial stage). Approximately three top varieties from each program were transferred to the other programs for testing. Varieties transferred to other programmes/regions are commonly referred to as “transfers”.

Data from the last 14 series of secondary variety trials for all the regions was analyzed to determine how “transfers” perform in other regions. Varieties from the southern regions do not excel when transferred to the northern irrigated region. A high percentage of transfers between the two coastal short cycle programmes are ranking within the top five varieties of the sister programme. Recommendations regarding transfers and possible implications for the regional breeding and selection strategy are discussed.

FIRST RESULTS OF A GENETIC MAPPING PROJECT OF

SUGARCANE SMUT RESISTANCE

Raboin L.M.¹, Offmann B.³, Hoarau J.Y.⁴, Notaise J.¹, Costet L.¹, Telismart H¹., Roques D.⁵,Rott P.², Glaszmann J.C.², Dhont A.²

¹ CIRAD BP20, 97408 St denis cedex 9, Réunion, France

²CIRAD Avenue Agropolis 34398 Montpellier cedex 5, France

³Université de la Réunion, BP 7151, 97715 Saint Denis Messag Cedex 09, La Réunion.

⁴CERF BP 315, 97494 Ste Clotilde, Réunion, France

⁵ CIRAD station de Roujol - 97170 Petit Bourg -Guadeloupe

Smut is one of the most important disease of sugarcane with a worldwide distribution. It can cause extremely severe yield losses if a susceptible variety is grown in a smut infested area. Resistance is therefore a major concern for most of sugarcane breeding centers. In Reunion Island the disease is present but controled by the use of resistant cultivars. This allows us to work with local inoculum.

We initiated a study on the genetic determinism underlying sugarcane smut resistance. We chose a genetic mapping strategy, focussed on a cross between R 570 (resistant) and MQ 76/53 (highly susceptible) which has shown a segregation for smut resistance in a preliminary field trial. An AFLP map is under construction for both parents of the cross. In the same time, field trials and greenhouse experiments have began using different artificial inoculation methods to assess the resistance of 200 progenies.

This paper presents first results on smut occurrence among these progenies and correlations between segregating markers and resistance to smut. The possibility of identifying the different components involved in the resistance and the interest of locus specific markers (SSR , resistance gene analogs, syntenic markers…) to refine the genetic map are discussed.

POSTER:

A GENETIC DATABASE ON SUGARCANE

Raboin L.M.¹, D'Hont A.²

¹ CIRAD BP20, 97408 St denis cedex 9, Réunion, France

²CIRAD Avenue Agropolis 34398 Montpellier cedex 5, France

A database has been built to rationalize storage and to improve accessibility to breeding and genetic data on sugarcane germplasm. It gathers pedigree information, agronomical information and also information on sugarcane genetic maps (AFLP genetic map, QTLS information, AFLP reference patterns, microsatellites characteristics). This database uses the ACeDB platform (AceDB software for Microsoft windows R. Durbin, J.thierry Mieg, R. Bruskiewich) designed for genomic data management.

As this growing database is supplied with more and more information about sugarcane genome organization (genetic and physical mapping of interesting traits, syntenic relationships), it should become a very interesting tool for Sugarcane breeders and geneticists.

A COMPARISON BETWEEN IRRIGATED VARIETIES

KA Redshaw and KJ Nuss

South African Sugar Association Experiment Station, Private Bag X02, Mount Edgecombe, 4300, South Africa

Abstract

The performance data of northern irrigated varieties from the SASEX Agronomy Departments’ variety trials and the final selection stages of the SASEX Plant Breeding Department were studied to provide extension staff and growers with information on which varieties should be grown in the different agroclimatic zones. The final selection stages of the Plant Breeding programme were included in this study to ensure that there was sufficient data on the more recently released varieties.

The performance of 12 sugarcane varieties (NCo376, N14, N19, N22, N23, N24, N25, N26, N28, N30, N32 and N36) grown under irrigation at the SASEX Pongola Research Farm and off-station sites in Pongola, Mpumalanga and Swaziland, was compared in terms of cane and sucrose yields. With the recent adoption of the RV payment scheme by the South African Sugar Industry, fibre and non-sucrose contents were included in the analysis. Estimated recoverable crystal (ERC) yields were used to estimate RV yields of these different varieties. The comparison was based on data from crops harvested early (Apr/May/Jun), mid (Jul/Aug/Sep) and late (Oct/Nov/Dec) season. Data on dry matter, fibre, sucrose and non-sucrose contents, radiation and heat units were included in this study for better evaluation of the varieties by both grower and miller.

DECISION SUPPORT PROGRAMMES FOR ASSESSING THE IMPACT OF IRRIGATED SUGARCANE ON WATER RESOURCES AND PROFITABILITY

E J Schmidt

Abstract

Water is a scarce resource in many sugarcane producing areas of South Africa. Sugarcane production competes with other crops as well as industrial and domestic water users for this resource. Legal and economic forces are driving renewed focus on water use efficiency and the sugar industry is frequently required to defend its allocation of water.

Decision support programmes (DSP’s) can play an important role in helping interpret the impact of alternative irrigation strategies on water resources and grower profitability. This paper illustrates the use of a number of DSP’s, developed at the SA Sugar Association Experiment Station, in a case study for the Umhlathuze catchment.

The paper illustrates:

The use of a hydrological model (ACRU) and database query programs (ACRUQuery and Genscn) to assess the impact of dryland and irrigated sugarcane on water resources.
The use of an irrigation economics programme (IRRIECON) to assess economic viability under varying irrigation strategies.
The use of Geographic Information Systems to interpret special trends across the study area.

POTENTIAL AND CONSTRAINTS OF SMALL HOLDER SUGARCANE PRODUCTION IN SWAZILAND

JT Sifundza and PB Ntuli,

Swaziland Sugar Association Extension Services

P O Box 367 Simunye, e-mail ssaes@ssa.co.sz

Smallholder development first occurred in the 1960’s with the establishment of Vuvulane Irrigated Farms. Some smaller projects followed. Major expansion plans were put forward in the early 1990’s. This larger development is mainly on Swazi nation land in both the North and South of the country. This paper reviews the successes and failures in the earlier projects. It then uses this information as a guide to meet the challenges of the new expansion that is planned.

The main parameters discussed are yield, quality, labour, finance, land, administration, skills, groups associations, individual participation, extension and research. The overall objective is to use the information as a guide to new smallholder development. In addition a method of evaluating success in the context of smallholder development will be examined.

BOILER BLOW-DOWN FLASH RECOVERY

Ish Singh & Franco Weyers

TSB Malelane

This paper describes the change in practice at the Malelane Mill whereby the flash vapour from boiler blow-down from the Mill’s 30 bar boilers, which was previously rejected to atmosphere, is now recovered.

Various vapour recovery options as well as the motivation for the flash recovery into the turbine exhaust steam range are discussed. Design issues for the flash vessel, valve and piping configuration, which resulted from the Hazop Study, are explained.

The recovery of 2,5 tons per hour of boiler blow-down flash equates to R250 000 pa in coal savings.

NEW DEVELOPMENTS IN THE PRODUCTION OF

HERBICIDE RESISTANT SUGARCANE

(Short Communication)

Sandra J Snyman, Busisiwe B Monosi and Barbara I Huckett

Biotechnology Department, South African Sugar Association Experiment Station (SASEX), Private Bag X02, Mount Edgecombe, 4300.

In a previously reported model study, sugarcane was genetically engineered with the pat gene conferring resistance to the herbicide, Buster®. The sugarcane cultivar used in that work was NCo310, which is no longer grown commercially, but responds well to tissue culture and transformation. The field performance of the herbicide resistant sugarcane was assessed and stable transgene expression observed over several ratoons with repeated herbicide application. However, the cost of the Buster® herbicide is particularly high. The use of one of the cheaper herbicides known to be as effective as Buster® could increase the returns per Rand spent on weed control by up to six times. More recently, therefore, a gene conferring resistance to a cheaper herbicide has been introduced routinely into commercial cultivars N12 and N19, which constitute 32% and 16% respectively of cane harvested annually in South Africa. Gene delivery by microprojectile bombardment was accomplished using five plasmid constructs, each containing the same herbicide resistance gene and the antibiotic selectable marker gene nptII, but differing in promoter characteristics. Plantlets were regenerated via either direct or indirect somatic embryogenesis and selection carried out on medium containing the antibiotic geneticin. Putatively transformed plants were subjected to herbicide spraying in the glasshouse where, to date, 68% have survived a sub-lethal dose which severely damaged control plants. Results have suggested that N19 is more amenable to transformation and regeneration than N12. In addition, it has been shown that the promoters chosen to drive the gene of interest and selection gene are of great importance. In this study CaMV 35S promoter derivatives proved to be effective in the genetic environment of sugarcane.

NEMATODES AND NUTRIENTS: ASSOCIATION BETWEEN PLANT-PARASITIC NEMATODES AND SOIL CHEMICALS.

Vaughan W Spaull¹ and Patrice Cadet²

¹SA Sugar Association Experiment Station/²IRD, Private Bag X02, Mount Edgecombe, KwaZulu Natal, 4300, South Africa

Abstract

The relationship between numbers of nematodes and various soil chemicals was investigated in sugarcane fields in South Africa. Soil samples were collected from small and large scale farms in several localities in KwaZulu Natal. Each sample was assayed for the numbers of the various genera of nematodes, for pH and for levels of Al, Ca, Fe, K, Mg, Mn, Na, P and Zn. Relationships between the nematodes and the soil factors were identified by coinertia analysis using ADE4 software. This showed that certain combinations of nematode and soil factor were strongly associated but the nature of the relationship was not consistent in the two farming systems. However for certain chemicals and certain nematodes the type of relationship was the same in both small and large scale farms. Thus in both farming systems the abundance of Pratylenchus, Helicotylenchus and Paratrichodorus was inversely related to soil pH and positively related to Fe levels. Numbers of Meloidogyne were positively related to pH and inversely related to Fe in the two systems. Consistent but weaker relationships occurred between both Al and Mn and the four nematode genera in the two farming systems. Numbers of Xiphinema showed no association with any of the soil characters in either the small or large scale farms.

Enhancement of Sugar Production

Part 2: Chromatographic Separation of Sugar Cane Molasses

HNP Stolz¹, PI Bekker¹, Y Bathany², MA Theoleyre²

¹TSB Product Development, PO Box 47, Malelane, 1320, RSA

²Applexion, 264 Avenue de la Mauldre, 78681 Epone, France

Abstract

The chromatographic separation of beet sugar molasses is a well known and well described process. In contrast the chromatographic separation of cane molasses is not well established. The paper describes the separation efficiencies of a simulated moving bed (SMB) chromatography pilot plant utilising cane molasses obtained from the Komati Mill. Experiences and observations are discussed.

cDNA-AFLP DIFFERENTIAL DISPLAY OF SUGARCANE (SACCHARUM SPP.) GENES INDUCED BY CHALLENGE WITH THE FUNGAL PATHOGEN USTILAGO SCITAMINEA (H. & P. SYDOW) (SUGARCANE SMUT)

(SHORT COMMUNICATION)

Thokoane L.N. and Rutherford R.S.

Biotechnology Department

South African Sugar Association Experiment Station

Private Bag X02

Mount Edgecombe, 4300

Abstract

Sugarcane smut, caused by the fungal pathogen Ustilago scitaminea H. & P. Sydow has been severe in most sugarcane growing countries at one time or another. To date, the most satisfactory method of control is the use of resistant varieties. The aim of this study is therefore to gain insight into resistance mechanisms with the possibility of isolating candidate resistance genes to be used as transgenes. The cDNA-AFLP technique was used to detect sugarcane differential gene expression in response to challenge by U. scitaminea. Sequence homology searches (http://www.ncbi.nlm.nih.gov/blast/blast.cgi) have identified a putative chitin binding receptor kinase, a Pto-like ser/thr protein kinase and an active gypsy type LTR retro-transposon expressed only in the resistant variety (N52/219) in response to challenge.

THE EFFECT OF CANE TRASH ON YIELD AND NUTRIENT DEPLETION FROM THE 61 YEAR OLD BT1 TRIAL ON AN ARCADIA SOIL FORM

R van Antwerpen and JH Meyer

Abstract

Several papers in the last four years were presented at SASTA and all has reported results from BT1 obtained at least 58 years after the trial was established and non has covered the period since 1939 to date. This paper will report on the yield trends and nutrient depletion as affected by the treatments (trashed and either fertilized or not fertilized, burnt with tops either left or removed and both either fertilized or not fertilized). It was determined that the capacity of the Arcadia soil form to sustain yields with out fertilizer was 18 years or 8 crops. It was also determined that the fertilized trashed treatment produced about 20 ton cane per hectare (variety N16) which contains about 150 kg N/ha, 20 kg P/ha and 260 kg K/ha. The value of these nutrients is in the order of R1300/20 ton trash for variety N16. In a mature trash management field about a third of these nutrient amounts are available to the immediate following crop and similar values specific to the variety planted can be used to reduce the amount of fertilizer to be applied.

EFFECT OF HAULAGE SYSTEM ON SOIL PHYSICAL PROPERTIES

AND YIELD

R van Antwerpen and E Meyer

Abstract

A range of haulage systems is used to extract cane from irrigated fields in the South African sugar industry with unknown consequences of infield compaction to the following crop. A trial was established on the 2^nd ratoon of variety N14 growing on a Shortlands soil from in the Kaalrug area near Malelane. Three types of haulage vehicles were used to compact the interrow at two soil moisture levels. Vehicles used included two 30 ton 6x4 rigid trucks with a 4-axle drawbar trailer, fitted with either standard radial ply tyres (V1) or Trelleborg high flotation tyres (V2). The third vehicle was a 52kW standard two-wheel drive agriculture tractor with a 5-ton walking beam axle basket trailer fitted with radial ply tyres (V3). Measurements made included soil water content, bulk density, soil strength (all made before and after compaction), population and yield. Cane stalk population on the Shortlands site was only reduced by V3 and yield was least affected V2.

Soil bulk density measurements showed that V2 produced the greatest surface compaction (50mm) and the lowest at two further depths of 150 and 300mm. V3 caused the highest bulk density increase at the latter two depths. Soil strength measurements showed that the highest values for all vehicles occurred at a depth of only 50 to 100mm and equal natural subsoil strength values at a depth of 150 to 200mm. In addition to the main trial at Kaalrug, an observation trial was also conducted at Mandini where 80kW tractors with two 2 axle 5 ton trailers fitted with conventional radial tyres (T1) and Trelleborg high flotation tyres (T2) were compared on a Westleigh form soil (very susceptible to compaction). Comparing the depth effect revealed increased soil strength to a depth of 200 to 250mm. The total mass of the latter vehicles were less than that used on the Shortlands site and illustrated the importance of soil differences on the depth of compaction by haulage vehicles.

Recent improvements in the sensitivity of testing methods to improve security and efficiency of sugarcane quarantine in South AFRICA

T. van Antwerpen

South African Sugar Association Experiment Station, P/Bag X02 Mount Edgecombe, 4300

The Plant Breeding Department at the South African Sugar Association Experiment Station imports sugarcane clones from other countries primarily for crossing purposes to broaden the genetic base of the parental breeding stock. The movement of clones involves a risk of introducing exotic pathogens that may be symptomless or latent, and may present a hazard to production of sugarcane in South Africa. Sugarcane stalks can be infected by various pathogens such as viruses, bacteria and phytoplasmas. To ensure that imported sugarcane does not carry disease it is quarantined and tested for the presence of a number of pathogens. Biotechnological and new serological methods have recently been introduced to improve the sensitivity and efficiency of diagnostic tests in quarantine. Shoot tip cultures are now being used to eliminate the YLS virus from important breeding material. Another improvement in the quarantine glasshouse is that local varieties are now pre-quarantined to provide disease-free cuttings that are exported to other sugar-producing countries of the world.

RAPID ASH ANALYSIS FOR MIXED JUICE

LF van Staden and M Govender

Sugar Milling Research Institute, University of Natal, Durban, 4041

Abstract

The determination of ash content via a conductivity measurement (conductimetric) offers a rapid, environmentally friendly alternative to the sulphated ash analysis (gravimetric) presently employed by the South African sugar industry. The good correlation (R² = 0,93) between the molasses conductivity and sulphated ash results, prompted further investigation into the potential application of conductivity ash measurements. Consequently, investigations were extended to include a comparison of the mixed juice ash results obtained via conductimetric and gravimetric analysis. The paper includes a detailed discussion of the results obtained during the 1999/2000 milling season.

NEW METHOD TO ASSESS VARIETAL RESISTANCE TO

SUGARCANE STEMBORERS

B.Vercambre¹, Cao Anh Duong ², R.Goebel ³ & B.Morin

¹CIRAD-Programme canne à sucre, TA 71/09, 34398 - Montpellier cedex 5, France

² ISCR, Crop Protection Division, Ben Cat – Binh Duong, Vietnam

³CIRAD-SASEX, Entomology Department, Mount-Edgecombe 4300, South Africa

Because of the closeness of varieties in a small plot, the usual varietal trial design is not adapted to give an accurate assessment of insect resistance using natural infestations, except to have of numerous trials. To assess the varietal resistance on the basis of a few damaged internodes in natural or artificial infestation, a new method entitled « Careful Attention and Scanning Interpretation of Damaged Internodes (CASIDI) » has set up, where each internode was cut according precise and standardized prodedures . The main objective is to obtain a reliable index on varietal susceptibility based on the ratio of damaged surface/internode volume .

AVAILABLE methods to assess the varietal resistance to sugarcane stalkborers

B.Vercambre¹, R.Goebel² & J.Rochat³

¹CIRAD-Programme canne à sucre, TA 71/09, 34398 - Montpellier cedex 5, France

²CIRAD-SASEX, Entomology Department, Mount-Edgecombe 4300, South Africa

³ CIRAD-Laboratoire d’entomologie, BP 20, 97408 - Saint-Denis Messageries Cedex 9 – Réunion, France

Sugarcane growing areas have a reasonably stable biological balance and chemicals to control the stalkborers are hardly wish. In this aspect, the varietal resistance could be constitute the main axis of an IPM strategy. In this paper, the main methods (laboratory or fields ones) to assess resistance against the stalkborers are listed, with some results obtained by the CIRAD team already available.

THE APPLICATION OF A HYDRAULIC DRIVE ON A PRESSURE FED WALKER MILL

Ben Vermaak

TSB Malelane

In the off-crop of 1998, a Hägglunds hydraulic drive was installed on the pressure feeder rolls of one of the Walker Mills at the Malelane Sugar Mill. The purpose of this new drive was to add an additional 250kW of power to the mill unit and to test it over a period against set maintenance reliability and production throughput criteria. This information would allow an informed decision to be made with regard to drive options for future Mill upgrades.

After initial teething problems, the hydraulic drive quickly proved itself from a reliability and throughput point of view. However, the achieved performance was not able to meet the set criteria for average bagasse moistures of less than 50%. This short paper discusses the efforts made to optimise mill performance by testing alternative mill settings and control philosophies. The results and problems experienced with the Hägglunds hydraulic drive are discussed.

CURRENT APPROACHES TO DEVELOPMENTAL-STAGE SPECIFIC AND ABIOTIC-STRESS RESPONSIVE GENE EXPRESSION PROFILING: PROGRESS AND PROSPECTS IN SUGARCANE

(SHORT COMMUNICATION)

Derek A. Watt, Barbara I. Huckett and Deborah L. Carson

Biotechnology Department, SA Sugar Association Experiment Station (SASEX),

Private Bag Mount Edgecombe, 4300.

The development of many molecular crop improvement strategies is expedited by the isolation of genes that participate in delivering the desired phenotype. Consequently, great effort has been devoted worldwide to the identification of developmental-stage specific and stress responsive genes in important crop and model plant species. The substantial rate of progress reported for many of those endeavours can be ascribed to the massive scale of the gene expression profiling initiatives that have emanated from animal and plant genome sequencing projects. However, the adoption of such approaches is costly and generally restricted to plant species for which large expressed sequence tag (EST) databases exist and are available within the public domain. For other plant species, including sugarcane, alternative approaches to identify differentially expressed genes must be sought. Recent research at SASEX has demonstrated that a combination of cDNA subtractive hybridisation and simple macro-array technology are effective in the identification of developmental-stage specific and abiotic-stress responsive genes. To date, this approach has yielded four genic fragments specifically associated with culm maturation. Also, preliminary findings have revealed that that a myriad of signalling and signal transduction events, similar to those involved in pathogenesis-related responses, are elicited in sugarcane roots challenged by phytotoxic levels of aluminium. This presentation outlines the scope of such gene expression profiling strategies and their potential application to sugarcane improvement.

CHARACTERISITCS OF SUGARCANE BORED BY ELDANA SACCHARINA WALKER

(LEPIDOPTERA: PYRALIDAE)

MJ Way

South African Sugar Association Experiment Station, P/B X02, Mount Edgecombe, 4300, South Africa

Abstract

This poster presents data from field trials to corroborate that juice quality, and to a lesser extent stalk mass, is adversely affected by Eldana saccharina Walker. Pol % cane is consistently lower in bored stalks. In contrast fibre %cane increases. Effects on stalk mass were unclear. Results were similar in the varieties studied namely NCo 376, N19 & N11.

DELIVERY EFFICIENCIES AND CANE QUALITY IN THE SOUTH AFRICAN SUGAR INDUSTRY: BENCHMARKING AND PENALTY ALLOCATIONS

Adrian Wynne

Technical Liaison Manager SA Canegrowers Assoc.

Abstract

The Recoverable Value (RV) cane payment system and length of milling season (LOMS) controls were introduced to incentivise growers to improve cane quality. As a consequence, the impact of delivery inefficiencies is accentuated because growers could be significantly prejudiced if cane quality is not considered in the timing of deliveries. Further prejudice could arise in terms of LOMS extensions and/or collective Local Area Agreement (LAA) penalties. This paper examines incentives within the current institutional framework surrounding cane supply and attempts to identify and correct existing delivery inefficiencies. The solution comprises a penalty allocation mechanism, which can be fully automated and incorporated into the LIMS system. It is flexible and can accommodate specific circumstances at the different mill centres. The mechanism comprises delivery window periods that are traded, which encourages selective harvesting of the best quality cane available. This should enhance the profitability of mill areas and the South African Sugar Industry as a whole. It also creates an incentive for growers to collectively reduce the impacts of accidental fires by informally exchanging delivery timings. The increased accountability for deliveries enables LAA penalties to be apportioned amongst those individuals responsible. Penalties raised could also be used by the Local Grower Council to create an “income stabilising fund” for its grower constituency. In addition, penalty payments can be transferred in part to responsible hauliers and contractors. The penalty allocation mechanism creates the necessary incentives for growers and their agents to improve their estimating and delivery performance.

Key Words: delivery, efficiency, quality, estimates, penalty, incentives

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* Present address: Rietspruit Farms, PO Box 11560, Dorpspruit, 3206

9. THE SUGARCANE GENOME : A SYNTHESIS OF CURRENT UNDERSTANDING, AND LESSONS FOR BREEDING AND BIOTECHNOLOGY

13. A – MOLASSES CLASSIFICATION AT GLEDHOW

15. OPERATION AND PERFORMANCE OF THE GRANULAR ACTIVATED CARBON PLANT AT NCHALO

22. LAND FORMING ON FLAT CLAY SOILS OR IMPROVED SUGAR CANE YIELDS

26. PATHOGEN AND PEST INDUCED GENE EXPRESSION IN SUGARCANE (SACCHARUM SPP.). INTEGRATING A PROGRAMME FOR MARKER DISCOVERY AND GENE ISOLATION

35. THE USE OF TISSUE BLOTS TO SCREEN FOR VARIETAL RESISTANCE TO RATOON STUNTING DISEASE

36. SOME MEASUREMENTS OF MECHANICAL SUGARCANE HARVESTING EQUIPMENT

37. SOIL DEGRADATION AS A FACTOR IN YIELD DECLINE IN THE SOUTH AFRICAN SUGAR INDUSTRY

38. A REVIEW OF THE EFFECT SOIL FERTILITY AND NUTRITION ON CANE QUALITY

39. A review of COMMERCIAL VARIETAL pERFORMANCE ON DIFFERENT SOILSAT MHLUME in SWAZILAND

43. FIRST RESULTS OF A GENETIC MAPPING PROJECT OF SUGARCANE SMUT RESISTANCE

44. A GENETIC DATABASE ON SUGARCANE

45. A COMPARISON BETWEEN IRRIGATED VARIETIES

46. DECISION SUPPORT PROGRAMMES FOR ASSESSING THE IMPACT OF IRRIGATED SUGARCANE ON WATER RESOURCES AND PROFITABILITY

47. POTENTIAL AND CONSTRAINTS OF SMALL HOLDER SUGARCANE PRODUCTION IN SWAZILAND

1Tongaat-Hulett Sugar LTD, Private Bag X3, Glenashley, 4022, South Africa

Abstract

PART 1: PRODUCTION OF WHITE SUGARAND CLEAN MOLASSES IN THE RAW HOUSE

Abstract

THE SUGARCANE GENOME : A SYNTHESIS OF CURRENT UNDERSTANDING, AND LESSONS FOR BREEDING AND BIOTECHNOLOGY

MK Butterfield1 and A D’Hont2

Abstract

ANNUAL AND LONG TERM BENEFIT OF NEMATODE CONTROL

ON YIELD OF SUGARCANE

Abstract

S Chetty and SB Davis

Sugar Milling Research Institute, University of Natal, Durban, 4041

D.E. Conlong¹ and A. Mugalula²

A – MOLASSES CLASSIFICATION AT GLEDHOW

Abstract

M de L Smit, MF Coetsee, and SEH Davies

OPERATION AND PERFORMANCE OF THE GRANULAR ACTIVATED CARBON PLANT AT NCHALO

Abstract

Abstract

Abstract

Abstract

Abstract

LAND FORMING ON FLAT CLAY SOILS OR IMPROVED SUGAR CANE YIELDS

Brent Griffiths and Neil Lecler

Zimbabwe Sugar Association Experiment Station

PATHOGEN AND PEST INDUCED GENE EXPRESSION IN SUGARCANE (SACCHARUM SPP.). INTEGRATING A PROGRAMME FOR MARKER DISCOVERY AND GENE ISOLATION (SHORT COMMUNICATION)

Biotechnology Department

South African Sugar Association Experiment Station

Private Bag X02

Mount Edgecombe, 4300

Abstract

ON SUGAR CANE GROWN ON THE NATAL SOUTH COAST

Malcolm Humm

P. O. Box 700, Umtentweni, 4235

Neil Lecler

Zimbabwe Sugar Association Experiment Station Private Bag 7006, Chiredzi, Zimbabwe

Abstract

N B Leibbrandt

Sugar Milling Research Institute, University of Natal, Durban 4001

Abstract

Swaziland

South African Sugar Association Experiment Station Mount Edgecombe

Abstract

A.J. Martin1,2, D.E. Conlong1 and R. Slotow2

THE USE OF TISSUE BLOTS TO SCREEN FOR VARIETAL RESISTANCE

TO RATOON STUNTING DISEASE.

SA McFARLANE

Abstract

SOME MEASUREMENTS OF MECHANICAL SUGARCANE HARVESTING EQUIPMENT

Abstract

SOIL DEGRADATION AS A FACTOR IN YIELD DECLINE IN THE SOUTH AFRICAN SUGAR INDUSTRY

A REVIEW OF THE EFFECT SOIL FERTILITY AND NUTRITION ON CANE QUALITY

JH Meyer and RA Wood

A review of COMMERCIAL VARIETAL pERFORMANCE ON DIFFERENT SOILS

AT MHLUME in SWAZILAND

Abstract

Abstract

F Olivier, A Singels & C.N Bezuidenhout

SASEX, Agronomy Department, Private Bag X02, Mt. Edgecombe, 4300

RC Parfitt & DW Thomas

Abstract

FIRST RESULTS OF A GENETIC MAPPING PROJECT OF

SUGARCANE SMUT RESISTANCE

A GENETIC DATABASE ON SUGARCANE

Abstract

¹Tongaat-Hulett Sugar LTD, Private Bag X3, Glenashley, 4022, South Africa

MK Butterfield¹ and A D’Hont²

A.J. Martin^1,2, D.E. Conlong¹ and R. Slotow²

¹TSB Product Development, PO Box 47, Malelane, 1320, RSA

²Applexion, 264 Avenue de la Mauldre, 78681 Epone, France

³CIRAD-SASEX, Entomology Department, Mount-Edgecombe 4300, South Africa

²CIRAD-SASEX, Entomology Department, Mount-Edgecombe 4300, South Africa