Recoverable Sugar Research Articles

Agronomic Performance of Sugarcane in Reduced Row Spacing Grown from Different Billet Sizes Under No-tillage and Conventional Tillage System

For the need for expansion in the production of sugarcane, especially in regions that do not yet produce it significantly, there is a necessity for new studies in such areas, such as the cerrado-pantanal transition region. Therefore, the present study aimed to evaluate the agronomic performance of the crop through different soil management and billets sizes in the region. The experiment was conducted at the State University of Mato Grosso do Sul, in Aquidauana, Mato Grosso do Sul, in the 2012/2013 harvest. The design was in blocks with randomized treatments, in 2 × 3 subdivided plots, with treatments consisting of the combination of two soil management (no-tillage and conventional tillage systems) and three billet sizes (10, 20 and 40 cm), with four replications. The variety used was RB867515, and the variables analyzed were number of tillers, plant height, percentage of gaps, stem diameter, stem mass, productivity and total recoverable sugar. It was concluded that the use of billets of 20 cm in length positively influenced the vegetative development of sugarcane, but it did not translate directly into productivity. The planting system also did not directly influence the agronomic performance of the crop.

Optimising the number of test sites, crop-years and replications to maximize post-release testing efficiencies

The South African sugar industry develops commercial sugarcane cultivars across multiple testing sites, crop-years and replications. The extent of such parameters has not been well quantified for optimum breeding and resource allocation. The objective of this study was to identify the optimum number of testing sites, crop-years and replications needed to maximize efficiency of post-release cultivar evaluations in South Africa. Ten commercial sugarcane varieties were evaluated in randomized block designs across five regions tested over five crop cycles. The study was conducted from the main plant to third ratoon crops across the locations. The general linear model was used to estimate variance components. Genotype × location (G×L) interactions were significant (p ≤ 0.01) for cane yield (TCANE), estimated recoverable crystal content (ERC), sugar yield (TERC) and fibre (F). Tonnes of estimated recoverable crystal were highly influenced by G×L interaction, suggesting that evaluating cultivars across locations is essential. High broad sense heritability estimates were observed for TCANE (71.17%), ERC (97.11%) and F % (93.11%), implying that these traits were genetically controlled. The G×L and G×L×C variances were the largest source of variation, suggesting that the evaluation of sugarcane cultivars across locations as opposed to crop cycles would be essential.

Genetic parameters and selection of sugarcane for borer resistance in the advanced selection stage

Abstract This study aimed to investigate genetic parameters and selection strategies for sugarcane resistance to borer and determine the effects of selection for borer resistance on yield traits. The infestation index by borer (IIB) and yield traits were assessed over 3 years in 35 sugarcane clones planted in four locations in southeastern Brazil. There was no genotype × environment (year or location) interaction for borer resistance. Consequently, selection may be performed at only one location and year or by the mean of clones in several locations and/or years. The borer population affected the genotypic variance for borer resistance but when genotypic variance was significant, heritability was elevated and suitable genetic gain was achieved. Selection for borer resistance reduced the genetic gains for tons of cane per hectare, theoretical recoverable sugar, and tons of sugar per hectare; however, satisfactory selection gains for both borer resistance and yield were achieved using selection index.

Performance of insecticides in control of Diatraea saccharalis (Lepidoptera: Crambidae) in sugarcane

ABSTRACT The population of the caterpillar Diatraea saccharalis (Lepidoptera: Crambidae) has increased in the crop of sugarcane in recent years. Although the control of this insect is traditionally carried out through biological control, the use of phytosanitary products has still been necessary. Therefore, the goal of this work was to evaluate the performance of different insecticides in sugarcane borer control, as well as the effect on productivity and total recoverable sugar (TRS). The experiment was conducted in a randomized experimental delineation of blocks, with six treatments and four blocks. Treatments consisted of five insecticides and one control group (without application of insecticide). For calculating the D. saccharalis infestation index, monthly samplings were performed every 30 days, for 12 months. After this period, the final D. saccharalis infestation index was evaluated and calculated for each treatment. In order to compare productivity among procedures, four central lines were collected from each plot. Thus, the samples were weighed for the productivity calculation (TCH) and sent to the laboratory for the total recoverable sugar (TRS) analysis. The chloranthraniliprole (350) insecticide provided a lower index of sugarcane borer infestation, in addition to greater productivity when compared to the other insecticides. There was no significant difference in the parameter of total recoverable sugar (TRS) among treatments.

Effect of Different Sowing Dates on Quantity and Quality of Some Promising Sugar Beet ( Beta vulgaris L.) Varieties under North Delta, Condition

MANY agronomic practices must be need modified to maximize quantity and quality of sugarbeet crop. Two field experiments were sconducted at Belkas town, Dakahlia Governorate, Egypt, near Dakahlia Sugar Company, during two successive winter seasons 2014/2015 and 2015/2016. A comparative study was conducted to assess the performance and stability of four multigerm sugar beet varieties (Beeta vulgaris L.), i.e. Dema-Poly, Pleno, Glloria and Ras-Poly in relation to three sowing dates, i.e. 1st September, 1st October and 1st November as well as their interaction to select the superior varieties in respect to highest yield and quality with suitable both early and late swing dates. A split-plot design with four replications was used. Results of study revealed that different sowing dates have significant effect on all beet characters. Sowing sugar beet plants at 1st October was significantly associated with the highest yields of root and sugar as well as quality traits in terms of sucrose (S%), purity % and recoverable sugar (R S%). On the other hand, leaf area index (LAI) and top yield ton/fed (fed= 4200m2) significantly decreased with delayed sowing dates. Sowing sugar beet plants at 1st September associated with maximum total soluble solids (T.S.S%) and impurities content, i.e. Na %, K %, α-amino N % as well as sucrose loss to molasses (SLM %) compared with late sowing date. Also, results clearly showed that the variances due to sugar beet varieties were significantly in all studied traits. Ras-Poly variety recorded the highest values of root dimension (cm), root fresh weight (gm/plant), root yield (RY) ton/fed, white sugar yield (WSY) ton/fed, sucrose %, purity % and recoverable sugar (RS%) followed by Dema-poly and Glloria in a descending order in both seasons. While, Glloria variety produced the maximum LAI and top yield (TY) ton/fed. The highest values of impurities content, i.e. Na %, K %, and α-amino-N %, as well as sucrose loss to molasses (SLM%) were recorded with planting Pleno variety on 1st September. Generally, sowing Ras-poly variety at the optimum date on 1st October produced the highest root, white sugar yields and lowest impurities content followed by Dema-poly and Glloria. While, the highest values of LAI and top yield ton/fed were obtained when Glloria variety planted on early date followed by Pleno variety under studied environmental conditions.

IMPACT OF PLANTING DENSITY, NITROGEN AND POTASSIUM FERTILIZER LEVELS ON YIELD AND QUALITY OF SUGAR BEET

Two field experiments were carried out at the experimental farm (Ghazala Village), Faculty of Agriculture, Zagazig University, Sharkia Governorate, during 2016/2017 and 2017/2018 seasons to study the influence of three planting densities, (28000, 35000 and 46666 plants/fad.) three levels of N fertilizer (80,100 and 120 kg/fad.) and two levels of potassium fertilizer (24 and 48 kg k2O/fad.) on yield and its attributes as well as quality of sugar beet grown in clay soil. Results of combined analysis illustrated that, decreasing planting density from 46666 to 35000 or 28000 plants/ fad., significantly increased root length, root diameter and fresh root weight g/plant; on the other hand the highest planting density (46666 plants/fad.) produced higher sucrose, extractable sugar percentages, sugar and recoverable sugar yields/fad., than low or medium densities. Raising N fertilizer levels significantly affected yield and its attributes as well as quality of sugar beet. Where, the results of the combined analysis indicated that, each increment of nitrogen fertilizer level from 80 up to 120 kg N/fad., cm was accompanied with a significant increase in root length, root diameter, fresh root weight/plant, root and recoverable sugar yields/fad., but significantly decreased sucrose (%). Data of combined analysis also revealed that application of 48 kg K2O/fad., significantly increased root yield attributes i.e., root length root diameter (cm), fresh root weight g/plant, sucrose, extractable sugar percentages, as well as, root and recoverable sugar yields ton/fad., compared with supply of 24 kg K2O/fad. Interactions between the studied factors (according to the combined analysis) indicated that the highest root yield (ton/fad.) was achieved when sugar beet was sown with the highest plant density of 46666 plants/fad., and fertilized with 120 kg N/fad. As well as, the highest value of root diameter (cm) was achieved under the application of 120 kg N/fad., and addition of 48 kg K2O/fad., while, the interaction between planting densities and potassium fertilizer levels had no significant effects on all studied traits.

Effects of depth-dependent irrigation regimes and organomineral fertilizers on water use and quality attributes of sugar beet

Experiments were conducted under provincial conditions of Kayseri, Turkey, for two years in the growing seasons of 2014 and 2015 to determine the effects of irrigation water applications based on different sugar beet root zone depths and different organomineral fertilizers on sugar beet yield, root quality, water consumption, and water use efficiency. Two constant root depths (D1 = 0.9 m and D2 = 0.6 m) and one active water extraction root depth (D3= 0.4-0.9 m) were investigated. A mineral fertilizer (F1), an organomineral fertilizer (F2), and organic + mineral fertilizer (F3) were considered as the subtreatments in the experiments carried out in a completely randomized block split-split plots design with 3 replications. Despite the lower nitrogen and phosphorus quantities applied, the F2 treatment produced the same sugar beet root yield (95.31 t/ha) as F1 (88.59 t/ha) and F3 (94.56 t/ha) treatments. The irrigation water requirements of D1 for two years were 22.8% and 27.6% greater than the D2 and D3 treatments, respectively. Irrigation water use efficiencies of D2 and D3 treatments were higher than D1. Digestion and recoverable sugar percent and Na, K, and N contents of roots were not affected significantly by the treatments. Using organomineral fertilizers would offer various advantages for disposing of huge urban waste deposits and returning organic matter to agricultural areas. Use of active root water extraction depth or 0.60-m root depth for irrigation applications will also contribute to efficient use of water resources and improve the income of sugar beet farmers due to reduced irrigation costs.

Atributos qualitativos e maturação de genótipos de sorgo sacarino

The aim with this work was to evaluate the qualitative parameters and maturation of eleven genotypes of sweet sorghum. Field experiment was carried out in Santa Maria locality, State of the Rio Grande do Sul, South Region, Brazil, in two growing seasons (2012/13 and 2013/14). The experimental design was randomized blocks with three replications and the treatments consisted of eleven genotypes, seven varieties (BRS506, BRS511, Fepagro 17, Fepagro 19, Past 81-04, Past 29-51 and Past 29-49) and four hybrids (CV007, CV147, CV568 and CV198). The qualitative parameters were evaluated: sucrose content (%), reducing sugars (%), purity (%), total soluble solids (°Brix), total recoverable sugar (kg t-1), fiber (%) and ethanol production (l ha-1). It was determined maturity curves to characterize the industrial use period (IUP). The genotypes BRS506, BRS511 and CV198 showed IUP over 30 days. BRS506 and BRS511 are genotypes with better features for ethanol production.

Industrial Quality of Sugarcane Under Fertigation with Nitrogen and Zinc

Both the excess and deficiency of nutrients in the soil can influence the technological quality of sugarcane stalks, and affect the quality of the juice, the fiber content, and the concentration of sucrose, which directly impact the quality and quantity of products derived from sugarcane. Thus, this study aimed to investigate the effect of nitrogen and zinc fertigation, irrigated by a central pivot, on various parameters that affect the industrial quality of sugarcane (IACSP 95-5000), in the plant and first ratoon crop cycles in a Cerrado Red Latosol soil in Brazil. The experiment was conducted under field conditions at an average altitude of 907 m in an area of the Rio Paraiso II farm of the Raizen Mill, in the municipality of Jatai, Goias (GO). The experiment was conducted in a randomized complete blocks design and analyzed in a scheme of 4 × 5 subdivided plots, with three repetitions. The treatments consisted of four nitrogen doses (0, 60, 120, and 180 kg ha−1) and five zinc doses (0, 2.5, 5.0, 7.5, and 10.0 kg ha−1), on plant cane and first ratoon cane. Urea served as the source of nitrogen fertilizer and was applied in three dosages (treatments) 60 days after planting. Zn sulfate served as the zinc source and was applied in four dosages (treatments) at a single time in the planting. At harvest, ten stalks were randomly sampled from each plot and sent to the Raizen Mill agro-industrial laboratory in Jatai-GO for analysis and to determine the polarizable amount of sugar per cane (Pol % cane), polarizable amount of sugar in the juice (Pol % juice), total soluble solids (Brix %), apparent purity, wet bagasse weight (WBW), reducing sugars, total recoverable sugar (TRS), and fiber content. The highest doses of zinc (10 kg ha−1) and nitrogen (180 kg ha−1) had the greatest effects on sugarcane WBW and TRS.

Relationship of Drone‐Based Vegetation Indices with Corn and Sugarbeet Yields

Successful adoption of drone‐based remote sensing depends on changes in sensitivity over vegetation indices (VIs) and growth stage(s). During 2017–2018, experiments were conducted to relate between vegetation indices and corn (Zea mays L.) and sugarbeet (Beta vulgaris L.) yields in western Minnesota. Aerial images were collected using an unmanned aerial vehicle (UAV) equipped with a passive light optical sensor (Micasense RedEdge). Using Pix4D software, spectral reflectance data were derived from flights at V6 and VT growth stages of corn, and V10 and V15 growth stages of sugarbeet in 2017. In 2018, images were collected every week from the V4 to R2 growth stages in corn, and from the V4 to V15 stages in sugarbeet. In addition to red normalized vegetation index (RNDVI) and red edge normalized vegetation index (RENDVI), crop height was determined from UAV based digital terrain and digital surface models. Yield prediction (YP) model was derived from the linear regression between crop yield and vegetation indices. For corn‐YP model, R2 value increased over the growing period and optimized at the R1 growth stage. Considering 3 site‐years, RENDVI was the best predictor for corn YP than other VIs based on the maximum R2 value. For sugarbeet YP, model R2 value declined over the growing season and optimized at V7 or V10 growth stages. Considering 4 site‐years, RNDVI was best related to root yield and recoverable sugar yield. Drone‐based remote sensing can be successfully used for corn and sugarbeet YP. Drone‐based remote sensing has potential in corn and sugarbeet YP, but it varied over growing seasons.Core Ideas Drone‐based passive optical sensor can be used to predict crop’s yield. Red‐ and red edge‐normalized vegetation index and crop height are potential indices. Red edge normalized vegetation index best correlated with corn yield. Red normalized vegetation index best correlated with root yield prediction. Over growing season predictability improved for corn but declined for sugarbeet.

Can We Select Sugarbeet Harvesting Dates Using Drone‐based Vegetation Indices?

In the Northern Great Plains, sugarbeet (Beta vulgaris L.) harvesting is stretched out from August to October. Sensors mounted on unmanned aerial vehicles (UAVs) may provide the information needed to identify sugarbeet approaching an optimum harvesting date that maximizes the recoverable sugar yield. The objective of this study was to relate the vegetation indices at early‐ and late‐harvest time with corresponding sugarbeet root yield, sugar concentration, and recoverable sugar yield (RSY) at three fields in the Red River Valley of North Dakota and Minnesota during 2017 and 2018. Vegetation indices was determined based on the multispectral imagery collected using UAV. Early harvest dates (19 Sept. 2017 and 21 Aug. 2018) reduced yield and RSY in 5 of 6 site‐years, compared to late harvest dates (3 Oct. 2017, 4 Sept. 2018, and 18 Sept. 2018). In general, delaying harvest increased red normalized difference vegetation index (NDVI) and reduced red edge NDVI (RENDVI). However, Pearson correlation between yield and vegetation indices did not show consistent relationship across harvesting date, site, and growing season. Pooling all site‐year data showed a significant relationship between RENDVI and yield and RSY. Use of in‐season yield estimate (RENDVI/growing degree days) has potential to explain 46% of sugarbeet root yield and RSY.Core Ideas Sugarbeet yield and sugar content is directly related to the length of growing season. Late harvest in September increased recoverable sugar yield. Sugar concentration did not change with harvest date. Association between drone‐based indices and yield varied with site‐year.

Effects of Foliar Application of Micronutrients on Agronomic Traits of Beet Cv. Sonja under Dsa (Hot Summer Continental) Climatic conditions of Naqadeh Iran

Plants need different macro and micro nutrient elements to grow and reproduce. Their malnutrition results in unhealthy growth. The soils of Naqadeh area, Iran are deficient in micronutrient elements. The aim of the study was to evaluate the effects of micronutrients application on some qualitative and quantitative parameters of economically important monogerm sugar beet cv. Sonja. The plants were foliar sprayed with iron, boron, zinc, and manganese. The studied traits were potassium, sodium, nitrogen, extraction coefficient, sugar percent, recoverable sugar, alkalinity, molasses, root yield, and white sugar recovery yield. The effect of micronutrients was significant on all studied traits. The highest extraction coefficient of 89.31 was related to the foliar application of iron (Fe) and the highest recoverable sugar percent (16.91%) was obtained from Zn application. Also, the highest mean root yield (74.120 t ha-1) and white sugar yield (12.137 t ha-1) were noted after foliar treatments of boron (B) and Fe, respectively.

Genotype-by-region interactions of released sugarcane varieties for cane yield in the South African sugar industry

ABSTRACTSugarcane (Saccharum spp.) yields in the South African sugar industry are affected largely by genotype by environment (G × E) interactions. The objectives of this study were to investigate the nature and magnitude of G × E interactions of selected sugarcane genotypes based on regional evaluation trials and to identify mega-environments to inform future testing strategies. The study was conducted across five regions in KwaZulu-Natal province. Ten sugarcane hybrids and one commercial check hybrid were evaluated using a randomized complete block design with four replications. Data collected were analyzed using the additive main effect and multiplicative interaction (AMMI 2) and genotype main effect plus genotype by environment interaction (GGE) bi-plot analyses. A combined analysis of variance detected significant variation for genotypes, locations, and crop year and their interactions for total cane yield, estimated recoverable crystal and sugar yield. Genotypes N19 and N40 showed broad adaptability for cane and sugar yields, whereas N51 and N12 were superior for sucrose percentage. High cane yields were achieved in the following environments: South Coast, North Coast, Hinterland and irrigated North regions. Overall, the Irrigated North region was the most suitable environment for discriminating among cultivars and for being a representative test environment. Two mega-environments (MGE) were identified for the industry; where Midland and Hinterland sites fell in the same MGE 1; and North Coast, South Coast, and Irrigated North were combined into MGE 2.

Agroindustrial best practices that contribute to technical efficiency in Brazilian sugar and ethanol production mills

The agricultural and industrial indicators that contribute to the efficiency of sugarcane mills were investigated in this study. A two-stage Data Envelopment Analysiswith output approach was applied to 271 mills for the data from the 2006/2007 season to the 2015/2016 season. The first stage consisted of the elaboration of two efficiency models using the total milling yield of the crop (t) and the amount of total recoverable sugars (t) as the input variables and the productions of sugar (t) and ethanol (m3) as the output. The second stage identified the production process variables significantly influencing the efficiency through multiple linear regression. In addition, with the help of sugarcane experts, ten variables related to the efficiencies of the agricultural and industrial processes of sugar and ethanol production, which contribute to the overall productivity of the sugar-energy units, and 40 best practices were developed to observe, improve, and control these indicators in order to increase the global efficiency of the agroindustrial production units.

Quantitative and qualitative analysis of sugarcane productivity in function of air temperature and water stress

Climate variables can influence the both productivity and quality of the commercial product of sugarcane crop. This study aimed to evaluate the influence of thermal time, negative degree-days and water deficit on productivity and industrial quality of sugarcane for the Goiás Brazilian Savanna region. The data of productivity and industrial quality were obtained in the field (Plant Centro Álcool®) and climate data in the weather station. Thermal time and the accumulation of negative degree-days in cycles showed significant correlations with the yield. The highest (340 mm) and the lowest (158 mm) accumulated water deficit blade not reflected in lower productivity and greater, respectively. Relative evapotranspiration (rET) was equal at 1.0 in more than 50% of the studied period, in which not were found significant correlations between the rET<1 with the productivity and industrial quality. We found significant correlations between rates of degree-days and negative degree-days with productivity rates; however, there was a low correlation between the water deficit rates and productivity. The total recoverable sugars rates and total soluble solids showed maximum accumulation point only in function of degree-day rates. We conclude that the thermal time has greater influence on yield decrease of sugarcane with different harvest cycles, significantly contributing to the accumulation of sugars in the stem.

Genotype x Harvest Cycles Interaction in Sugarcane on the South Coast of Pernambuco

Aims: To quantify the magnitude of the genotype x harvest cycle interaction (GxC) of sugarcane during three harvest cycles and to select superior clones for cultivation on the Coast of the Southern Forest of Pernambuco.
 Study Design: The experiment was conducted in a randomized complete block design.
 Place and Duration of Study: Evaluated during the 2011/2012, 2012/2013 and 2013/2014 harvest years in the agricultural area of the Cucaú Plant, located in the Municipality of Rio Formoso (8°39' 49" S and 35º09'31" W, altitude of 5 m), Microregion of the Southern Forest of Pernambuco.
 Methodology: 11 genotypes Republic of Brazil of the RB 2004 series and three RB cultivars were evaluated. Each plot was represented by five grooves of 8.0 m in length, spaced in 1.0 m, totaling 40 m². The crops were harvested 15 months after planting (MAP) for the first crop cycle and 12 MAP during the two subsequent cycles were evaluated tons of sugarcane per hectare (TCH), tons of pol per hectare (TPH) and total recoverable sugar (ATR). The variance analyses, the Scott and Knott clustering test, the estimative of the simple and complex parts of the G x C interaction and the Pearson correlation coefficient were processed in the Genes program.
 Results: The genotypes showed a significant reduction of TCH from the first to the second cycle and that only the genotype UFRPE11 showed a significant decrease for the third. The genotypes UFRPE10, UFRPE6, UFRPE11, UFRPE7, UFRPE2, UFRPE9 and UFRPE1 exceeded all commercial varieties in TPH. It was observed for the variable ATR that there were no significant differences between the genotypes in the third cycle. The simple fraction of the interaction G x C were predominant between cycles C1 and C2 for TCH (67.91%) and TPH (69.35%), while for ATR (56.42%) the complex fraction was predominant. For the pair C2 x C3, the simple fraction of the interaction G x C predominated only in the TCH (62.85%) and TPH (62.41%) variables, but was not significant for the variable ATR. It is worth mentioning that the C1 x C3 cycle pair presented predominantly complex type interactions for all variables TCH (50.42%), TPH (52.20%) and ATR (59.66%).
 Conclusion: The simple fraction of the genotype x harvest cycles (G x C) interaction provides genetic gain for yield of sugarcane and sugar in selection in subsequent pairs of harvest cycles, year by year. The complex fraction of G x C interaction reduces the predictability of genetic gain, making it difficult to select new cultivars. Local selection favors expressive genetic gain in a few selection cycles. However, it does not favor the selection of genotypes with high adaptability and phenotypic stability, requiring tests in several environments. The UFRPE06 and UFRPE10 clones can be selected to continue the selection cycles for the southern coastal conditions of the Mata de Pernambuco.

SOIL PHYSICAL ATTRIBUTES AND PRODUCTION COMPONENTS OF SUGARCANE CULTIVARS IN CONSERVATIONIST TILLAGE SYSTEMS

Machine traffic and conventional tillage can cause structural degradation of the soil, affecting the physical attributes and, consequently, the production and longevity of the sugarcane field. The objective of this study was to evaluate the production components of sugarcane cultivars (RB965902, RB985476, RB966928, RB855156, RB975201, RB975242, RB036066 and RB855536) and physical attributes of a Dystroferric Red Latosol (Oxisol) under no-tillage and reduced-tillage systems. The experiment was conducted using a completely randomized experimental design in an 8 × 2 factorial arrangement, with four replicates. The soil attributes evaluated were density, total porosity, macroporosity, microporosity and penetration resistance. The production components evaluated were stalk length and diameter, number of tillers (NT), tons of cane per hectare (TCH), sucrose content (Pol), tons of sucrose per hectare (TPH), soluble solids content (Brix), total recoverable sugars (TRS) and plant fiber. Cultivars RB965902, RB966928, RB855156 and RB985476 have productivity and technological attributes that are superior to the other cultivars, whereas these are lower for RB036066 in both soil tillage systems. Cultivars RB966928, RB855156, RB975242 and RB855536 exhibited higher TCH and TPH in the no-tillage system, and all cultivars displayed equal or higher performances than those observed in the reduced-tillage system. In the no-tillage system, which exhibits lower penetration resistance values between wheel tracks and in the subsurface layer of the planting row (0.20–0.40 m), cultivars RB985476 and RB975242 had a higher NT, and RB855156 had higher stalk lengths and NT.

Genetic Variabilities and Genetic Gains for Yield Components in Regional Sugarcane Breeding Programmes on R\xe9union Island

Sugarcane variety development programmes are costly and lengthy. It appears important to periodically assess their ability to select competitive genotypes for yield components and provide genetic gains. This article reports a 10-year retrospective analysis of successive variety trials conducted in four regional breeding programmes on Réunion Island in the most advanced regional selection stage. The four variety programmes were dedicated to the humid coastal zone (LM), the per-humid coastal zone (SB), the irrigated dry coastal zone (ES) and the dry high lands (VB) of the local industry. Using mixed linear models, the objective of the study was to (1) assess genetic variabilities available for yield components in this advanced selection stage; and (2) estimate trends of genetic gains achieved over the last decade across the four programmes. Yield components were: cane yield (CY), estimable recoverable sugar (ERS), fibre content (FIB) and economic index (EI). Broad-sense heritabilities were high (0.70–0.91) for all traits in each programme. Mean genetic coefficients of variation were about twice as high for CY (14.1%) and EI (15.5%) compared to ERS (5.7%) and FIB (6.6%). A higher probability of identifying superior varieties was found for CY and EI in two of the four programmes characterized either by thermal and hydric stresses (VB) or by an edaphic stress (SB). Simple linear regression of variety performances versus years of selection revealed trends in genetic gains for EI ranging between 0.53 and 1.81% increase per year that were highly significant (P < 0.001) in the two programmes (LM and VB).

TECHNOLOGICAL STUDIES ON PERFORMANCE OF SOME SUGAR CANE VARIETIES

The present study was carried out to study performance and milling quality of theplant (PC), first (FR), second (SR) and third ratoon (TR) crops of two varieties of sugar cane i.e., Giza99/103 and Giza 99/160 during period from January to March of 2016/2017 working season. Bothvarieties were planted under comparable conditions at Kom Ombo Sugar Cane Research Station Farm,Aswan Governorate, Egypt. Results revealed that both varieties gave the highest normal juiceextraction average of 79.2% by the onset of January, bagasse (%) cane showed an opposite trend tonormal juice extraction whereas G 99/103 and G 99/160 recorded 36.8 and 37.3%, respectively. Thehighest pol extraction reported for G 99/160 was 93.2 and lower pol (%) bagasse (2.64) compared to3.15 for Giza 99/103. Sucrose reduction factor of the standard variety G 99/103 showed insignificantvariations among the different crops with an average of 0.98 for all the crops and 0.97 with G 99/160variety. G 99/160 variety had an average varietal correction factor of 0.986. The recorded generalaverage for all crops and test dates for pol (%) cane, estimated recoverable sugars, pol (%) normaljuice and normal juice purity for the variety Giza 99/103 were 16.00, 14.75, 18.82 and 88.65;respectively, compared to 14.63, 13.41, 17.50 and 88.2 for Giza 99/160 variety.

Development and Yield of Irrigated Sugarcane as Affected by Nitrogen Sources and Rate in Brazilian Cerrado Oxisol

Sugarcane is the most promising crop among renewable biofuels producers and one of the countries that produces the most green matter per unit area, whose greater limitations to productivity are mainly related to the adequate availability of water and mineral nutrients, in particular nitrogen (N). Based on the hypothesis that the source and the availability of nitrogen influence the growth, development and yield of irrigated sugarcane in the cerrado region. The objective of this study was evaluate the biometric variables and yield of irrigated sugarcane, in the cane-plant cycle, as affected by source and nitrogen rate. The soil utilized was an Oxisol (Rhodic Hapludox), cerrado (savannah) phase. The experiment was carried out at Farm of the Ra&amp;iacute;zen Mill, located in the municipality of Jata&amp;iacute;, Goias State, Brazil. The variety IACSP95-5000 was used in a randomized block design, analyzed in a split-split-plot scheme, with three replicates. The treatments were four N rates (0, 60, 120 and 180 kg ha-1); two fertilizer sources (urea and ammonium nitrate). The factors evaluated were in the plots of four doses of N (0, 60, 120 and 180 kg ha-1). In the subplot two sources of N (urea and ammonium nitrate) and as sub-subplot were represented by four evaluation periods (210, 250, 290 and 330 days after the planting-DAP). The irrigation was by sprinkling, in a central pivot. The evaluated variables were: plant height, stalk diameter, total number of leaf, leaf area, number of industrializable tillers, stalk yield, pointer yield and total recoverable sugars. The highest stalk yield, pointer yield and total recoverable sugars occurred at the average dose of 143.61 kg ha-1 of N, with an average increase of 25.87%.