Sugarcane Research Institute Research Articles

Cultural-practice packages and trash management effects on sugarcane ratoons under sub-tropical climatic conditions of India

SUMMARYSugarcane (Saccharum spp.) ratoon crops comprise more than 0·50 of India's sugarcane acreage and reduce the cost of cultivation by 25–30%. However, ratooning is seldom practised beyond 1–2 ratoons because the yield declines in successive ratoons due to compacted soils with decreased fertility restricting root development and plant growth. Therefore, a field experiment on sugarcane was conducted from 1998 to 2003 at the Sugarcane Research Institute, Muzzaffarnagar (Uttar Pradesh), India to evaluate the effects of combinations of trash management with key cultural practices (stubble shaving, ridge dismantling, sub-soiling along stubble rows, trash mulching and earthing-up) on growth and yield of sugarcane up to the third ratoon. Two treatment combinations (ridge dismantling+stubble shaving+sub-soiling along stubble rows+trash mulching at 8 t/ha (T5) and all these plus earthing-up in June (T6)) showed similar growth, yield and economics of ratoon crops. Both these treatments produced significantly higher shoot populations, leaf area index (LAI), dry matter (DM) accumulation, net assimilation rate (NAR), number of millable canes, ratoon cane yield and sugar, soil organic carbon (SOC) content at harvest and higher net returns besides lowering weed density, weed dry weight and bulk density of soil compared with other treatments. T6 produced the highest cane yield of 77, 72 and 65 tonnes (t)/ha, which was 23, 27 and 29% more than trash burning alone (T1) in first, second and third ratoon crops, respectively. Although T6 had the same yield as T5, it led to significantly lower soil bulk density at 0–150 mm depth, higher SOC contents and greater benefit: cost ratios in the first, second and third ratoon crops, respectively compared with trash burning only. Adoption of the crop management components, separately or in combination, improved on trash burning only (the control treatment). Trash mulching sustained the improved yield and economic returns of sugarcane ratoon crops.

Varietal Variation in Stomatal Conductance, Transpiration and Photosynthesis of Commercial Sugarcane Varieties Under Two Contrasting Water Regimes

The study was conducted to evaluate some physiological characters of commercial sugarcane varieties under different growing conditions in Sri Lanka. A field experiment was conducted at the Sugarcane Research Institute, Uda Walawe (6°21'N latitude, 80°48'E longitude and 76 m altitude) using eight sugarcane ( Saccharum hybrid L.) varieties grown under irrigated and rainfed conditions in a split plot de-sign. Stomatal conductance ( g s ), instantaneous transpiration rate ( E 1 ) and photosynthetic rate per unit leaf area ( P n ) were measured. Canopy stomatal conductance ( g c ), instantaneous canopy transpiration rate ( E c ) and transpiration efficiency ( P n / E 1 ) was calculated. The behaviour of g s in many respects to the moisture availability and growing stage was similar to the responses seen in P n . Water deficit significantly reduced g s , E 1 and P n . Recovery of g s and P n from water stress with rainfall was quite rapid under rainfed conditions. The varieties Co775, SL8306, SL7103 and SL88116 which had higher P n and P n / E 1 , and lower g s , E 1 , g c and E c showed comparatively superior physiological performances under rainfed conditions. Water conservation through lowering stomatal conductance, both at the individual leaf and canopy level, and higher photosynthetic rate were identified as some physiological mechanisms responsible for drought tolerance of sugarcane. Key words: Sugarcane; Stomatal conductance; Transpiration; Photosynthesis; Water regimes DOI: 10.4038/tare.v12i2.2798 Tropical Agricultural Research & Extension 12(2): 2009 pp.97-102

Potential of spectroscopic data sets for sugarcane thrips (Fulmekiola serrata Kobus) damage detection

Sugarcane thrips was detected in South African sugarcane in 2004. Since then it has become widespread in South Africa. The South African Sugarcane Research Institute (SASRI) conducts field surveys to monitor this pest, but this is time intensive and costly. As a first step towards evaluation of remote sensing for thrips monitoring, a preliminary experiment and analysis at leaf level were conducted using a handheld field spectroradiometer covering the 350 to 2500 nm range of the electromagnetic spectrum to detect sugarcane thrips damage. Reflectance spectra of sugarcane leaves with different levels of thrips damage, from two popular varieties (N19 and N12), were measured and statistically analysed using one-way analysis of variance, sensitivity analysis and canonical discriminant analysis. The results of the analyses showed that there were significant differences in spectral reflectance and derived variables used in the study at the different levels of damage. The red edge region of the visible portion gave the highest significant differences and levels of separability among the damage classes. It is hypothesized that this might be associated with chlorophyll and nitrogen deficiencies induced by thrips.

Definitive identification of orange rust of sugarcane caused by Puccinia kuehnii in Cuba

In November 2008, leaf lesions, pale yellow to yellow-orange, sometimes coalescing in large necrotic areas, were observed on hybrid sugarcane clones (Saccharum spp.) CSG 86-504, CSG 24-92, CSG 204-92 and CC 87-409 at the Sugarcane Research Institute (INICA) Station in Villa Clara province, in central Cuba. Specimens were submitted to the Central Plant Quarantine Laboratory for identification. The observed morphological features were consistent with those described for Puccinia kuehnii (Virtudazo et al., 2001; Comstock et al., 2008). Uredinial lesions, variable in size (3–4 mm in length), were generally light brown in colour, but occasionally yellow-orange to cinnamon brown. Hypophyllous uredinia were ellipsoidal to fusiform in shape, distinctly lighter and less uniformly distributed than for P. melanocephala. Urediniospores were mostly obovoid to pyriform, almost ellipsoidal in shape, variable in size, 27·5–55·0 (41·9) × 17·5–37·5 (26·0) μm, echinulate with evenly distributed spines. Walls (orange to light cinnamon brown in colour) were 1–2·5 μm thick, often with a pronounced apical thickening, 3–7 μm (mode 5 μm). Four to five equatorial pores were present. In contrast to P. melanocephala, paraphyses were not visible in stereoscopic views of the uredinia and were absent in most specimens. Telia and teliospores were not observed. Total DNA isolation from symptom-bearing leaves with uredinia was performed according to Lin et al. (2001). A real time PCR was conducted using the SYBR green technique with primers synthesized from exact sequences of ITS1, 5·8S, and ITS2 of the large subunit rDNA region reported in GenBank Accessions EU164549 and EU176009 (Comstock et al., 2008). Results confirmed the identification as P. kuehnii. Previous reports of P. kuehnii in Cuba (Commonwealth Mycological Institute, 1969) were based on misidentifications of P. melanocephala. To the authors’ knowledge, P. kuehnii has not been reported by any diagnostic laboratory in Cuba in the last 30 years. In addition, Cuba was not included in the latest P. kuehnii distribution map (CAB International, 2007). Therefore, this is the first confirmed report of the presence of P. kuehnii in Cuba. The disease has since been found in different localities in the central and eastern regions of Cuba, without any reported economic losses to date.

Phenotypic diversity of plant morphological and root descriptor traits within a sweet potato, Ipomoea batatas (L.) Lam., germplasm collection from Tanzania

In Tanzania sweet potato ranks as the third most important crop after cassava and potato. We studied the phenotypic diversity of morphological plant and root descriptor traits in accessions of the sweet potato germplasm collection of Sokoine University of Agriculture, Morogoro and Sugarcane Research Institute, Kibaha, Tanzania, using phenotypic characters. A total number of 105 sweet potato accessions of different geographic origins were studied in field trials of The Sugarcane Research Institute at Kibaha Tanzania, and data were recorded for 27 phenotypic characters. Estimates of pair-wise phenotypic similarities using the Manhattan coefficient varied from 0.023 to 0.814, with a mean of 0.285. Cluster analysis was conducted using the unweighted pair group method with arithmetic mean (UPGMA) and Principal Coordinate Analysis (PCO). The clustering of phenotypic data resulted in a dendrogram which was discordant with geographic origin and AFLP data. The analysis of variance (ANOVA) revealed highly significant variation among the accessions for 21 out of the 27 characters studied. Phenotypic analyses revealed a wider range of variability than AFLP analyses. Comparison of molecular and phenotypic data using the Mantel test showed a very low correlation (r2 = 0.0007). Molecular and phenotypic classifications are discordant, and both are necessary to classify the germplasm correctly and to clarify genetic relationships among sweet potato accessions.

Sugarcane genetic engineering research in South Africa: From gene discovery to transgene expression

Over the past 15 years, recombinant DNA and in vitro culture technologies have been used in concert at the South African Sugarcane Research Institute (SASRI) to genetically engineer sugarcane. The purpose of such research has been two-fold, viz. to establish proof-of-principle regarding the delivery of novel input and resistance traits to sugarcane and to investigate the genetic basis of sucrose accumulation. Underpinning these goals has been the in-house development of essential genetic resources, including the isolation of appropriate transgenes and gene promoter elements, and the optimisation of transformation and tissue culture technologies. With regard to the latter, emphasis has been placed on the development of tissue culture strategies that minimise the potential for somaclonal variation, while maximising the efficiency of germplasm transformation, selection, regeneration and acclimation. The isolation of promoters to drive high-level and targeted transgene expression, as well as the identification of DNA sequences with the potential to deliver the desired phenotype, have been strongly driven by advances in gene discovery and expression technologies. Early approaches relied on the analysis of Expressed Sequence Tag libraries constructed from sugarcane tissues at different developmental stages or challenged with selected abiotic and biotic stress agents. Subsequent improvements in DNA subtractive hybridisation technologies (e.g. suppression subtractive hybridisation) and gene expression analysis (e.g. Affymetrix® Sugarcane Genome GeneChip) provided new and powerful means for gene and promoter discovery. Reviewed here are the advances in in vitro culture, gene discovery and transgene expression research, which have formed the foundation of the genetic engineering program at SASRI. Also discussed are the opportunities and challenges in these areas of research that are presented by the availability of ultra-high throughput DNA sequencing (e.g. the 454 Sequencing System) for transcriptome analysis and technologies for rapid and accurate profiling of the sugarcane metabolomes.

A DECISION SUPPORT SYSTEM FOR SUGARCANE VARIETY SELECTION IN SOUTH AFRICA BASED ON GENOTYPE-BY-ENVIRONMENT ANALYSES

SUMMARYThe objective of this study was to develop a basic variety selection decision support system (DSS) based on industry legalities, varietal characteristics and structured genotype-by-environment (G × E) analyses. Trial data extracted from a variety trial database at the South African Sugarcane Research Institute (SASRI) were categorized into different regions, harvest ages (12, 18, 24 months) and harvest seasons (early, mid, late season harvests). Restricted maximum likelihood analyses were conducted regionally to determine varietal adaptability to different harvest ages and seasons. Highly significant variety × harvest age and variety × season interactions allowed for the appropriate categorization of varieties. Varietal adaptability to different yield potential conditions was determined using the sites regression technique, and varietal adaptability was interpreted from the slope of the regression curves. The analysed data were used to create simplistic ‘yes/no’ spreadsheets, which were housed within a relational database. A web interface linked to the database allows users to specify characteristics of their production environment. The system then selects appropriate varieties that conform to specified criteria and eliminates non-compliers in a stepwise approach. The system was subsequently validated against expert extension specialist opinion and acceptable performance was observed.

Post-harvest biology of sugarcane

Cutting of the sugarcane stalk at harvest disrupts the physiology of the plant. The altered balance amongst plant functions that results from cutting leads to changes in the composition of the stalk, many of which are undesirable. These negative effects are worsened by increased duration of the period between harvest and sucrose extraction, as well as by high ambient temperature. In addition to physiological changes within the stalk, damage to the stalk during harvesting provides entry points for microbes (bacteria and fungi) that occur naturally in the environment. Many of these microbes grow well in the sucrose-rich stalk, using the sugars as an energy source, while producing metabolic by-products that cause processing problems in the mill and refinery. Post-harvest physiology and microbiology of the sugarcane stalk are currently being studied at the South African Sugarcane Research Institute (SASRI) to determine the effects of harvesting on sucrose and hexose (glucose and fructose) levels, the growth of microbes in the stalk and the appearance of undesirable by-products of microbial metabolism. The information will ultimately be used in the development of mathematical models to quantify and predict the effects of harvest-to-crush delays on stakeholder profitability.

Effects of Organic and Inorganic Fertilizer on Growth, Yield, and Juice Quality and Residual Effects on Ratoon Crops of Sugarcane

ABSTRACT Field experiments were carried out for three consecutive years (2003–2006) at Bangladesh Sugarcane Research Institute farm soil on plant (first crop after planting) and subsequent two ratoon crops of sugarcane. The main objectives of the study were to assess the direct and residual effects of organic and inorganic fertilizer on growth, yield, and juice quality of plant and ratoon crops. The plant crop consisted of four treatments. After harvesting of plant crop to evaluate the residual effects on ratoon crop the plots were subdivided except the control plot. Thus, there were seven treatments in the ratoon crop. Application of recommended fertilizer [nitrogen (N150), phosphorus (P52), potassium (K90), sulfur (S35), and zinc (Zn3) kg ha− 1] singly or 25% less of it either with press mud or farmyard manure (FYM) at 15 t ha− 1 produced statistically identical yield ranged from 67.5 to 69.0 t ha− 1 in plant crop. In the ratoon experiment when the recommended fertilizer was applied alone or 25% less of its either with press mud or FYM at 15 or even 7.5 t ha− 1 again produced better yield; it ranged from 64.8 to 69.2 in first ratoon and 68.2 to 76.5 t ha− 1 in second ratoon crops. Results showed that N, P, K, and S content in leaf progressively decreased in ratoon crops over plant crop. Juice quality parameters viz. brix, pol, and purity % remained unchanged both in plant and ratoon crops. Furthermore, organic carbon (C), available N, P, K, and S were higher in post harvest soils that received inorganic fertilizer in combination with organic manure than control and inorganic fertilizer treated soil. It may be concluded that the application of 25% less of recommended fertilizer (N112, P40, K68, S26, and Zn2.2.5 kg ha− 1) either with press mud or FYM at 15 t ha− 1 was adequate for optimum yield of plant crop. Results also suggest that additional N (50% extra dosage) keeping all other fertilizers at the same level like plant crop i.e. N168, P40, K68, S26, and Zn2.25 kg ha− 1 either with press mud or FYM at 7.5 t ha− 1 may be recommended for subsequent ratoon crops to obtain good yield without deterioration in soil fertility.

Effect of biocompost application on sugarcane crop

A field experiment was conducted during spring of 2006–07 at Sugarcane Research Institute, Shahjahanpur using sugarcane variety CoS 97264 to work out the effect of biocompost ( prepared from biodegradation from pressmud) application on yield and quality of sugarcane crop and status of organic carbon content in the soil before planting and after harvest of the crop. It is clear from experimental results that highest cane yield was achieved in the treatment 50 % N through biocompost + 50 % N through inorganic source followed by the treatments 33 % N through biocompost + 67 % N through inorganic source and 75 % N through biocompost + 25 % N through inorganic source. The cane yield of treatments with biocompost application showed significantly superior over the treatment without biocompost application. Furthermore, all the treatments were significantly superior over control. A slight improvement in sucrose % in juice at 10th and 12th month of crop age was observed in the treatments with biocompost application but it was not significantly superior. The soil organic carbon status was not only significantly restored in the treatments with biocompost application but it was also significantly improved in the treatments with 50 and 75 per cent biocompost application. In contrary, restoration mechanism of soil organic carbon was checked in the treatment with total R.D.N. through inorganic source and in control (no input).

South African Sugarcane Research Institute: Embracing biotechnology for crop improvement research

The South African Sugarcane Research Institute (SASRI) is a leading agricultural research institute and the only one of its kind in Africa conducting research into the development of new varieties, improving crop management and farming systems to enhance sugarcane productivity. In addition, effective delivery of new knowledge and technology make a significant contribution to the sustainability of the sugar industry in southern Africa. Variety Improvement and Crop Protection are key focus areas of research that have embraced modern molecular technologies to advance both conventional breeding and integrated control of pests and diseases.

Site Specific Fertiliser Requirement of Sugarcane and Intercrop (Onion) under Sugarcane Based Cropping System

A field experiment was conducted intercropping sugarcane with onion at Rajshahi under High Ganges River Floodplain and Thakurgaon under Old Himalayan Piedmont plain of Bangladesh to determine the site-specific nutrient requirements of cane and intercrop, onion, and their economics under sugarcane based cropping system. Cane yield was enhanced when it was intercropped with onion because of the residual effect of fertiliser applied to the onion.. Gross return and gross margin were greater in cane intercropped with onion over sole crop. The treatment T5 that received fertilisers for sugarcane (N150P52K90S35Zn3 and N140P37K100S25Zn2 kg/ha) and onion (N52P21K50S15 and N50P20K50S15 kg/ha) as per Bangladesh Sugarcane Research Institute Recommendation’1998 at Rajshahi and Thakurgaon site, respectively showed higher gross margin and benefit cost ratio at both the locations under study. Keywords: Site specific fertiliser, sugarcane, intercrop, cropping system

Analysis of genetic diversity in a sweet potato (Ipomoea batatas L.) germplasm collection from Tanzania as revealed by AFLP

Sweet potato (Ipomoea batatas L.) is the fifth most important crop in the developing countries after rice, wheat, maize and cassava. The amplified fragment length polymorphism (AFLP) method was used to study the genetic diversity and relationships of sweet potato accessions in the germplasm collection of Sokoine University of Agriculture, Morogoro and Sugarcane Research Institute, Kibaha, Tanzania. AFLP analysis of 97 sweet potato accessions using ten primer combinations gave a total of 202 clear polymorphic bands. Each one of the 97 sweet potato accessions could be distinguished based on these primer combinations. Estimates of genetic similarities were obtained by the Dice coefficient, and a final dendrogram was constructed with the un-weight pair-group method using arithmetic average. AFLP-based genetic similarity varied from 0.388 to 0.941, with a mean of 0.709. Cluster analysis using genetic similarity divided the accessions into two main groups suggesting that there are genetic relationships among the accessions. Principal Coordinate analysis confirmed the pattern of the cluster analysis. Analysis of molecular variance revealed greater variation within regions (96.19%) than among regions (3.81%). The results from the AFLP analysis revealed a relatively low genetic diversity among the germplasm accessions and the genetic distances between regions were low. A maximally diverse subset of 13 accessions capturing 97% of the molecular markers diversity was identified. We were able to detect duplicates accessions in the germplasm collection using the highly polymorphic markers obtained by AFLP, which were found to be an efficient tool to characterize the genetic diversity and relationships of sweet potato accessions in the germplasm collection in Tanzania.

A novel method to determine larval mandibular wear of the African stalk borer, Eldana saccharina Walker (Lepidoptera: Pyralidae)

The African stalk borer, Eldana saccharina Walker (Lepidoptera: Pyralidae), is the most significant indigenous pest on sugarcane in South Africa (Atkinson 1980; Conlong 2001). Currently, crop management and cultivar resistance in sugarcane remain the most widely accepted control methods for E. saccharina in South Africa (Nuss & Atkinson 1983; Keeping 2006). Following emergence, E. saccharina larvae graze up and down the sugarcane stalk or disperse onto dead leaf sheaths for several days until old enough and, presumably, with sufficiently strong mandibles to bore into the plant (Leslie 1993). As young larvae use their mandibles to chew through the sugarcane stalk, abrasion of the mandibles’ chewing surface is inevitable and could ultimately reduce feeding efficiency. It is recognized that fertilization with silicon (Si) can enhance the resistance of plants to insect attack, including that of sugarcane to E. saccharina (Keeping & Meyer 2002, 2006; Kvedaras et al. 2007). Testing the effects of this treatment highlighted a need to measure the extent of wear on larval mandibles. While there have been studies that have reported wear of chewing mouthparts of insects, they have either failed to describe the method (Djamin & Pathak 1967), used a method which can only be applied to mandibles of the same size (Raupp 1985) or have not accounted for differences in mandibular size between individuals (Kokko et al. 1993). The objective of this study was to develop an accurate and repeatable method to measure the mandibular wear experienced by E. saccharina larvae fed on commercial sugarcane. It is anticipated that the method will be useful in quantifying mandibular wear in other adult and larval chewing insects. A method is described that uses a simple image analysis technique to determine the loss of feature on the chewing edge of the mandible. Ten third instar E. saccharina larvae were randomly sampled from commercial sugarcane cultivars N26 and N11 grown at the South African Sugarcane Research Institute (SASRI), Mount Edgecombe, KwaZulu-Natal. Larvae were placed directly into 70 % alcohol until required. Prior to analysis, the larvae were removed from the alcohol, allowed to air dry for 10 min and their heads removed under a light microscope. The labrum was removed and using a fine tipped dissecting needle, the mandibles were carefully pried apart to avoid chipping and air-dried for 1 h. The heads were mounted with their mandibles in a horizontal position using black, double-sided carbon tape (12 mm × 20 m, Structure Probe Inc., West Chester, U.S.A.), on standard aluminium scanning electron microscopy (SEM) stubs. Debris on the mandibles was removed using a fine dissection needle and a fine camel hair brush. The specimens were gold coated for 3.5 min (approx. 6 nanometres thickness) using a gold sputtercoater (Polaron E5100 coating unit and E5500 film thickness moniter, Polaron Equipment Limited, Watford Hertfordshire, U.K.). Specimens were viewed using a scanning electron microscope (Leo 1450 Scanning Electron Microscope, Cambridge, U.S.A.) and the images captured digitally. Each mandible has two scissorial teeth and a proximal tooth, the mola. The degree of wear of a mandible was quantified using an algorithm to obtain a mean square error (MSE), as follows. The (x,y) coordinates (x = horizontal, y = vertical) of the pixels in the digital image that represent the chewing edge of the mandible, from the distal to the proximal convex protrusion (distal scissorial teeth and mola tooth) (Fig. 1), were subjected to linear regression. As the chewing edge of each mandible is carefully orientated under a microscope in a vertical direction, the deviation in the X-axis is the most relevant measurement, hence the best-fitting straight line is calculated as:

China: An emerging sugar super power

Sugarcane production in China has more than 3000 years of history. Prior to 1840 A.D., China dominated the world trade of cane sugar but the sugar industry became very week since then due to long time of wars and unstable social conditions. It has been developing rapidly again since early 1980s. China has become the third largest sugar producer in the world with 10.02 million tons of sugar output in 2003/04 and sugarcane contributed to 94.0% of the total sugar output. Guangxi is the biggest sugarcane growers Province in China, and it produced 5.88 tons of sugar which occupied 58.4% of the total sugar and 62.3% of the cane sugar in China, respectively in 2003/04. The other two key sugarcane and cane sugar producing Provinces in China are Yuanan and Guangdong Province. The capitation consumption of sugar was 6.9 kg/person in 2002, and it has increased rapidly in the recent years. Drought is the most important constraint for the sugarcane production, and other key limitations include low temperature, frost, insect pests (mainly borers, aphids, thripid and scarabs), diseases (mainly ratoon stunting disease, mosaic, pineapple and smut), weeds and rats. China has established its unique effective technologies for sugarcane production especially for the production in upland which occupied 90% of the total sugarcane growing area in the country. The millable cane productivity remained 60 to 70 tons/ha in China in the recent years. More than 100 sugarcane varieties have been bred and released for commercial sugarcane production since 1950s, and the variety GT11, bred by the Guangxi Sugarcane Research Institute and released since December 1980, boasts the biggest commercialised area, that is, 1.33 million hectares of land area since 1985. The ratoon crops occupied about two third of the total sugarcane growing area, Inappropriate field management and diseases like ratoon stunting disease and mosaic are the most important factors that limit the commercial ratoon cane productivity at present. The milling duration is from mid November to the end of April next year, and chemical ripening has been used to increase the sucrose % cane at early milling stage. The intercropping is very popular in the sugarcane fields with various crops such as vegetables, melons, pulse crops, potato, corn, mushrooms and green manure crops.

Effect of top borer(scirpophaga exerptalis wlk.) infestation on quality of jaggery

A study was undertaken to investigate the effect of cane infested with top borer (Scirpophaga exerptalis Wlk.) on gur quality during 1999 to 2001 at Sugarcane Research Institute, Shahjahanpur (U.P.). The gur samples obtained from healthy and infested canes (3rd, 4th and Sth broods) of an early maturing and high sugar variety CoS 95255 were subjected to qualitative analysis. The results revealed significant maximal losses in terms of brix pol %, purity, colour and invert sugar in the canes infested with 3rd brood followed by 4th and 5th broods of top borer in comparison to healthy canes. The minimal brix of gur (85.88) and pol % (45.56) were recorded in samples obtained from cane infested with 3rd brood as compared to those obtained from healthy canes (i.e. brix 94.18 and pol % gur 80.85). The highest invert sugar (17.10) was recorded in gur from 3rd brood infested canes as compared to those of healthy canes (6.55).

BIOCHEMICAL COMPOSITION AND ENZYMATIC ANALYSIS OF SUGARCANE VARIETIES Isd-16 AND Isd-28

An experiment was conducted at Bangladesh Sugarcane Research Institute (BSRI), Ishurdi, Pabna, Bangladesh. In this study, biochemical composition, enzyme activity and some chemical parameter of sugarcane juice in the varieties Isd-16 and Isd-28 were investigated. Isd-28 showed higher amount of brix (20.85%), pol (18.53%), fiber (19.93%), ash (6.95%), minerals (Na 1.36 & K 3.12 gm/100 gm ash) and lipid (0.058%) than that of Isd-16. Other compositions such as reducing sugars (0.096%), commercial cane sugar (12.55%), moisture (88.97%), protein (0.328%) and vitamin-C (0.00351 gm/100 gm juice) were lower in Isd-28. Amylase enzyme activity (44.44 unit/ml) and cellulase enzyme activity (7.15 unit/ml) were higher in Isd-28 but invertase enzyme activity (10.88 unit/ml) was lower than that of Isd-16. Purity (91.34%) and extraction percentages (54.63%) were higher in Isd-16 whereas, recovery percentage (11.17%) was lower in the juice of Isd-16 variety than that of variety Isd-28 of sugarcane. Most of the biochemical compositions analyses were higher in Isd-28 than that of lsd-16. Reducing sugars were less in Isd-28 variety indicating less invertase activity.

Response of sugarcane (Saccharum spp. hybrid complex) varieties to various planting geometry

A field experiment was conducted at Sugarcane Research Institute, Bihar, Pusa (Samastipur) during spring season of 201213 on sandy-loam soil, to examine the performance of sugarcane ( Saccharum spp. hybrid com- plex) varieties to different planting geometries. The treatments comprised 4 planting geometries, viz. 120, 150, 30:

Productivity and water-use efficiency of spring-planted sugarcane (Saccharum sp. hybrid complex) under various planting methods and irrigation regimes

A field experiment was conducted during the spring seasons of 201012 at Sugarcane Research Institute, Bihar, Pusa (Samastipur), to investigate the effect of planting methods (conventional, paired row and furrow-irri- gated raised bed system) and irrigation regimes [Irrigation water : cumulative pan evaporation (IW: CPE) ratios of 0.50, 0.75 and 1.00] on productivity and water-use efficiency of sugarcane ( Saccharum sp. hybrid complex). Num- ber of millable canes increased by 12.4% in conventional method, followed by 7.2% in paired row over furrow-irri- gated raised bed system (FIRBS) respectively. Cane yield obtained under conventional method of planting was higher over paired row and FIRBS by 5.7 and 12.9% respectively. The water requirement, water-use efficiency and water productivity were higher under conventional method followed by paired row and FIRBS planting. Conven- tional method of planting fetched significantly higher net returns ( 142.4 103/ha) followed by paired row ( 136.4 103/ha) and FIRBS ( 112.5 103/ha). Significantly higher benefit : cost ratio was recorded in paired row planting (3.21) than FIRBS planting (2.68) whereas it remained at par with conventional method (3.13) of planting. Among the irrigation regimes, irrigation at an IW: CPE ratio 1.00 significantly enhanced all the growth and yield-attributing characters. Though the differences between IW: CPE ratios of 1.00 and 0.75 and 0.75 and 0.50 were not signifi- cant. However, crop irrigated at an IW: CPE ratio of 1.00 gave significantly higher number of millable canes (110 103/ha) and cane yield (98.0 t/ha) being at par with an IW: CPE ratio of 0.75 and both the treatments showed supe- riority over that of an IW: CPE ratio of 0.50. Sucrose content in juice was not influenced significantly due to differ- ent irrigation regimes. Crop irrigated with an IW: CPE ratio 1.00 showed the maximum values of water requirement, water-use efficiency and water productivity. Net return increased markedly with increase in irrigation regimes from an IW: CPE ratio of 0.50 to 1.00. Irrigation at 0.75 and 1.00 IW: CPE ratio increased the net returns by 29.0 and 39.5% over that with the 0.50 respectively. However, an IW: CPE ratio of 1.00 (3.24) being at par with that of 0.75 (3.11) gave significantly higher benefit: cost ratio than that of 0.50.

Effect of early evaluation of genotypes on genetic variability repeatability and predictability in plant and ratoon crops of sugarcane

Genotypic and phenotypic coefficients of variation (GCV, PCV), heritability, genetic advance in per cent of mean, genetic relationship, repeatability and predictability were studied on plant cane and the first ratoon of sixteen early maturing sugarcane genotypes for yield characters and sugar content at Sugarcane Research Institute, Shahjahanpur, India. Result showed that the GCV, PVC, heritability, genetic advance in per cent of mean were higher for stalk weight, NMC and yield in both plant and ratoon crops, whereas stalk height was higher only in ratoon. Repeatability of characters between crops was 0.97**, 0.96**, 0.97**, 0.79**, 0.75** and 0.71** for juice brix, sucrose per cent (7 months), yield (10 months), stalk height, number of stalk and stalk diameter (7 months), respectively. The genetic association among characters were relatively low in both crops (r = -0.15 to 0.78), stalk diameter was the most predicatable characters followed by stalk number, stalk height, juice brix and sucrose per cent at grand growth stage for yield potential of genotypes in plant cane as well as ratoon. These characters may serve as a reliable selection critaria for yield and sucrose accumulation of early maturing high sugared genotypes from plant cane to the first ratoon. There were best estimated at 7 months when the genetic expression for yield contributing and quality characters were maximum.