Yield and Quality in Main and Ratoon Crops of Grain Sorghum Under Different Nitrogen Rates and Planting Densities

Ratooning is the cultivation practice of two harvests in one cropping season by producing a second crop from the original stubble, which could provide higher resource use efficiency and economic benefit compared with direct sown crops. Nitrogen (N) fertilizer and planting density (D) play a vital role in sorghum (Sorghum bicolor L.) production; however, limited information is available on the effects on yield and quality of the sorghum-ratoon system. To address this question, field experiments were conducted with three N treatments (120 kg N ha–1, N1; 180 kg N ha–1, N2; and 255 kg N ha–1, N3) and three D treatments (82,500 plant ha–1, D1; 105,000 plant ha–1, D2; and 127,500 plant ha–1, D3). The yield of the main crop was significantly higher than that of the ratoon crop. Increasing N could increase the yield and yield attributes of both main and ratoon crops, and the effect on the ratoon crop was greater than the main crop. With increasing D, the grain yield of both main and ratoon crops increased, though 1,000-grain weight and grain weight per ear decreased. The sorghum grain of the ratoon crop contained higher starch, protein, and tannin contents but lower fat content, indicating a better quality for liquor production. The quality traits were significantly affected by N and D, but the differences between treatments were smaller than that between the main and ratoon crop. Our results indicated that increasing the yield of ratoon crops could obtain a high yield and quality of the sorghum-ratoon system. It was recommended that 120 kg N ha–1 with 127,500 plant ha–1 for the main crop and a small amount of N be top-dressed in three new buds left on stubble in each hill for the ratoon crop.

Performance of High Yielding Promising Sugarcane Variety for Western Zone of Tamilnadu

Sugarcane is an important commercial crop cultivated in over 23,000 ha in Erode district of TamilNadu state. Attempts were made by researchers and extension workers to improve the productivity of sugarcane by adopting high yielding varieties and improved production technologies. The on-farm trials were conducted during Kharif 2017 and 2018 in five farmers’ field to assess the performance of high yielding promising sugarcane varieties suitable for Western Zone of TamilNadu. The varieties selected for trial were Co 86032 and Co 0212. The study revealed that Co 0212 recorded more number of productive tillers per plant (10.4), intermodal length (14.51 cm), stem girth (11.22) and individual cane weight (1.511 kg) which was superiorly higher than the existing variety Co 86032. Similarly Co 0212 recorded the yield of 127.5 ton / ha during 2017 which was 17.24 per cent higher yield than the existing variety and 138.86 ton / ha recorded and 30.68 per cent yield advantage was noticed in the ratoon crop. The highest benefit cost ratio of 2.44 was recorded in Co 0212 in ratoon crop and 2.05 in first crop where as 1.73 and 1.86 BCR observed in Co 86032 in first and ratoon crop respectively. Considering the above facts, Co 0212 would be identified as a better alternate variety suitable for the Western Zone of TamilNadu

Utilization of a Sugarcane100K Single Nucleotide Polymorphisms Microarray-Derived High-Density Genetic Map in Quantitative Trait Loci Mapping and Function Role Prediction of Genes Related to Chlorophyll Content in Sugarcane

Chlorophyll is the most important pigment for plant photosynthesis that plays an important role in crop growth and production. In this study, the chlorophyll content trait was explored to improve sugarcane yield. Two hundred and eighty-five F1 progenies from the cross YT93-159 × ROC22 with significantly different chlorophyll contents were included as test materials. The chlorophyll content of the +1 leaves during elongation phase was measured using a SPAD-502 meter through a three-crop cycle (plant cane, first ratoon, and second ratoon). Linkage analysis was conducted on a high-density genetic map constructed based on the sugarcane 100K SNP chip. In addition, Fv/Fm, plant height, stalk diameter, brix data were collected on plant cane during the elongation and maturation phases. The results showed that the +1 leaf SPAD values, which can be used as an important reference to evaluate the growth potential of sugarcane, were significantly and positively correlated with the Fv/Fm during elongation phase, as well as with plant height, stalk diameter, and brix during maturity phase (P < 0.01). The broad sense heritability (H2) of the chlorophyll content trait was 0.66 for plant cane crop, 0.67 for first ratoon crop, and 0.73 for second ratoon crop, respectively, indicating that this trait was mainly controlled by genetic factors. Thirty-one quantitative trait loci (QTL) were detected by QTL mapping. Among them, a major QTL, qCC-R1, could account for 12.95% of phenotypic variation explained (PVE), and the other 30 minor QTLs explained 2.37–7.99% PVE. Twenty candidate genes related to chlorophyll content were identified in the QTLs plus a 200-Kb extension region within either sides, of which four were homologous genes involved in the chlorophyll synthesis process and the remaining 16 played a certain role in chlorophyll catabolic pathway, chloroplast organization, or photosynthesis. These results provide a theoretical reference for analyzing the genetic mechanism of chlorophyll synthesis and subsequent improvement of photosynthetic characteristics in sugarcane.

Integration of physical approach and chemical approach for the control of banana rhizome rot in first and ratoon crop of banana cv. KovvurBontha (ABB)

India is the major producer of the banana crop in the world. Banana is divided into two types. First one is desert type and the second one is the cooking type of banana. Cooking banana is the stapple food in many parts of the India especially in Kerala. Major problem in cooking variety is that these varieties are highly susceptible to rhizome rot disease. To control this integration of physical method (collection and destruction) and chemical method (application of fungicide and bactericide) was used at an interval of 7 days and 14 days. The results showed that combination of physical method and application of MetalaxylMz (4 mgL-1) + streptomycin (1.5 mg/10L) at 7 days interval had resulted in survival percentage (96.03%), average number of the fingers/hand (12.67), average number of the hands/bunch (9.27), average weight of the bunch (29.67 kg) and yield per hectare (61.58 t/ha) in first crop. on the other hand, ratoon crop had recorded maximum survival percentage (99.83%), maximum average number of the fingers/hand (13.00), maximum average number of the hands/bunch (8.53), maximum average weight of the bunch (28.41kg) and maximum yield per hectare (59.45t/ha). This experiment concluded that rhizome rot can be completely control by the integrated physical and chemical method of disease management.

Evapotranspiration and Crop Coefficient of Ratoon Rice Crop Determined by Water Depth Observation and Bayesian Inference

Actual crop evapotranspiration (ET) and crop coefficient (Kc) of ratoon rice crop, which are necessary for irrigation planning, have been hardly reported. ET can be directly measured by lysimeter and eddy covariance but it is expensive, so it remains difficult to determine ET, especially in developing countries. The focus of this study was to evaluate the ET and Kc of ratoon cropping in a tropical region of Myanmar using a simplified method. Our method combined the manual observation of water depth in concrete paddy tanks and the ET model estimation using Bayesian parameter inference. The ET and Kc could be determined using this method with an incomplete observation dataset. The total ET of ratoon was 60–70% less than that of the main crop, but this difference was mainly attributed to climate conditions in each cultivation. The Kc regression curve between transplanted rice and ratoon crops was different because of the tillering traits. The results suggest that irrigation scheduling of ratoon cropping in the initial growth stage should take high crop water requirements into account. In addition, the productivity of ratoon crop is equivalent to transplanted rice, which was determined for cultivation in experiment conditions of small concrete tanks. Therefore, further study on ratoon in Myanmar is necessary for clarifying the viability of ratoon cropping.

Use of Liming and Incidence of Diseases in Sugarcane

This study aimed to evaluate the incidence of red rot, brown leaf spot, and smut in ten sugarcane genotypes during two consecutive cycles, in the absence and presence of limestone. The experimental design consisted of randomized blocks with four replications, in the presence and absence of liming in the following sugarcane genotypes: G1 (RB002754), G2 (RB021754), G3 (RB041443), G4 (RB863129), G5 (RB93509), G6 (RB951541), G7 (RB962962), G8 (RB992506), G9 (SP79-1011), and G10 (VAT90-212) for genotype x environment interaction. The lowest incidences of red rot were observed in G3 (RB041443), G4 (RB863129), G8 (RB992506), and G9 (SP79-1011) for plant cane, and in G3 (RB041443), G4 (RB863129), G5 (RB93509), G8 (RB992506), and G9 (SP79-1011) for ratoon. All genotypes were susceptible to Colletotrichum falcatum, but limestone reduced its incidence in G3 (RB041443), G6 (RB951541), and G10 (VAT90-212) during the first growth cycle, and in G1 (RB002754), G2 (RB021754), G5 (RB93509), G6 (RB951541), G7 (RB962962), and G10 (VAT90-212) in the ratoon crop. Liming also reduced the incidence of brown leaf spot in G4 (RB863129), G6 (RB951541), and G9 (SP79-1011) in plant cane and G6 (RB951541) and G7 (RB962962) in the ratoon crop. Only the G9 genotype (SP79-1011) showed an incidence of smut. The genotypes had different incidence levels of red rot, brown leaf spot, and smut diseases, which varied in the presence of limestone. Limestone use reduced disease incidence as a function of genotype and cutting cycle.

Coinoculaton of endophytic diazotroph with PGPR and AM fungi for enhancing sugarcane production

The field experiment was conducted at Sugarcane Research Station, Cuddalore during 2010 – 2012, to evaluate the response of sugarcane variety CoC 24 to the application of bioinoculants viz., Gluconoacetobacter diazotrophicus, AM fungi and Azophos (Azospirillum and phosphobacteria), under different levels of N, P2O5 and K2O inorganic fertilizer in plant and ratoon crop. The results revealed that the application of mycorrhizae, G. diazotrophicus, Azospirillum and phosphobacteria significantly produced higher cane yield in plant crop. The application of Gluconoacetobacter diazotrophicus @10 kg + AM fungi + Azophos @10 kg + 75 % NPK recorded the maximum germination and tiller population and also maximum mean millable cane population of 1.32 lakhs /ha, cane yield (137.45 t/ha) and sugar yield (16.96 t/ha). Similar results were recorded with the ratoon crop. The population of Azospirillum and Pseudomonas are higher compared to that of Glucanoacetobacter diazotrophicus and phosphobacteria. The application of bioinoculants improves soil microbial biomass and their by enhancing soil organic matter content. The applied bacterial sources helps in nitrogen fixation and also in continuous mobilizing and solubilisation of nutrients and their persistence and colonization in soil is an added advantage and also enhances the soil fertility. The usage of these bioinoculants inturn reduces the inorganic fertilizer input and thereby reduces the cost of cultivation.

Influence of Cultivars and Nitrogen Fertilizer Rates and Application Mode on Yields and Quality Parameters of Ratoon Sugarcane in Western Kenya

Productivity of sugarcane in Kenya has declined despite use of recommended production practices including introduction of elite high yielding and early maturing sugarcane varieties. Farmers continue to use recommended agronomic inputs for the old low yielding and late maturing varieties on these elite varieties. Nitrogen fertilizer rates in single or split doses for old varieties are still in use yet their appropriateness on new varieties remains untested culminating to decline in sugarcane productivity in Kenya. Currently, cane payment is based on delivered milling cane weight. The industry plans to change payment to a combination of quality and yields. Influence of agronomic inputs and timing of harvesting period on proposed mode of payment is unknown. Harvesting age in western Kenya remains 18-20 months after ratooning (MAR). However, optimal age that combines quality and yields is not documented. Influence of these agronomic practices on quality, yields and optimal harvesting age of ratoon crop of new (D8484) and old (CO421) varieties were evaluated in a 2x4x3 split-split-plot design replicated three times. Four rates of nitrogen as urea, all applied at 3 MAR, split once (50-50%) and applied at 3 and 6 MAR or split three times (40-30-30%) and applied at 3, 6 and 9 MAR were evaluated. Yields and quality parameters were monitored from 10th-24th MAR. Variety D8484 out-yielded (p≤0.05) CO421 throughout demonstrating its superiority. Yields reached maximum at 20 and 19 MAR for CO421 and D8484, respectively. Maximum pol and brix were attained at 18 and 15 MAR for CO421 and D8484, respectively, while commercial cane sugar (CCS) was maximum at 18 and 17 MAR for CO421 and D8484, respectively. Results demonstrated that for high returns, D8484 should be harvested between 15-18 MAR while CO421 between 17-19 MAR. The 60 kg N/ha, that produced higher (p≤0.05) output in both varieties, from 16th MAR is recommended for both varieties. Split fertilizer application did not affect productivity.