Integrated Physiological Approach for Sustainable Productivity Post Harvest Seed Quality Attributes of Soybean Under Different Environments

Abstract

Soybean, known as the quotgolden beanquot or quotmiracle bean,quot is a major oilseed crop in India, valued for its high protein and oil content. Climatic adversities have further impacted soybean production and seed quality during the Kharif season. Shifting sowing to the Rabi season and delaying sowing until January under irrigated conditions can help avoid abiotic stress, maintain seed yield and seed quality. Plant growth regulators (PGRs) are known to enhance yield and promote desired growth within a given area and timeframe. Based on this, experiment were designed with Rabi on soybean in 2020-21 and 2021-22 with treatments comprising two dates of sowing (D1 Rabi and D2 Rabi summer), two spray schedules (S1 foliar spray at the vegetative stage and S2 foliar spray at the flowering stage), and plant growth regulators (Salicylic acid at 250 ppm and 500 ppm, Thiourea at 500 and 1000 ppm, Cycocel at 100 ppm, and IBA at 200 ppm), and atno spray of PGR i. e. control). newline In our study, sowing soybean in Rabi (D1) significantly delayed flower initiation, pod formation, seed formation, physiological maturity, harvest maturity compared to Rabi summer sowing (D2). Sowing soybean in Rabi (D1) increased dry matter accumulation in leaves, stem and branches, total dry matter accumulation at 45 DAS, 75 DAS, leaf area and leaf area index at 30 DAS, 45 DAS and 74 DAS, leaf area duration at 30-45 DAS, 45-75 DAS, relative growth rate at 45-75 DAS, biomass duration at 30-45 DAS, 45-75 DAS, chlorophyll content index at 75 DAS, relative water content, membrane stability index, PAR interception, photosynthetic rate, stomatal conductance, water use efficiency, plant height at 75 DAS and at harvest, no. of branches plant-1, no. of pods plant, seed yield (g plant-1 and kg ha-1), biological yield (g plant-1 and kg ha-1), seed index, GDD for flower initiation and pod formation, fiber content, fat content and moisture content as compared to Rabi summer (D2). Sowing soybean at early date (1st jan) (D1) resulting in maximum seed yield (2424.40 kg ha-1) with higher net monetary return (Rs. 70141.06 ha-1) and higher benefit-cost ratio (1.59) in soybean as compared to date sown (Rabi summer) condition, i. e. last week of January (D2). newline Foliar spray of plant growth regulators at the time of vegetative stage (S1) significantly increased maximum dry matter accumulation in leaves at 45 DAS, net assimilation rate (mg cm-2 day-1) during 30-45 DAS, and the number of branches plant as compared to S2 (foliar spray of PGRs at the time of flowering stage). Foliar spray of PGR at the flowering stage (S2) significantly delayed physiological maturity, higher dry matter accumulation in stem and branches at 45 DAS, relative growth rate during 30-45 DAS, number of pods plant-1 as compared to S1 (foliar spray of plant growth regulators at the time of vegetative stage. newline Application of foliar SA at 500ppm was found best in increasing Leaf biomass at 45DAS, Leaf area at 75 DAS, LAI at 75 DAS, RWC, MSI, Canopy temperature depression, Stomatal conductance, no. of pods plant-1, Seed yield (9.39 g plant-1 and 2347.71 kg ha-1), Biological yield (29.58 g plant-1 and 7395.52 kg ha-1), seed Index, net monetary return (Rs. 66,115.99 ha-1) and B:C ratio (1.49) as compared to control. Foliar application of Thiourea at 500 ppm (T4) significantly delayed days to flower initiation and physiological maturity as compared to control (T1). TU at 500 ppm showed superiority in increasing dry matter accumulation in stem and branches at 45 DAS, total dry matter accumulation at 45 DAS, CGR at 45 75 DAS, RGR at 30 45 DAS, NAR at 30 45 DAS, BMD at 30 45 DAS and 45 75 DAS and plant height at harvest as compared to no PGR spray (T1). newline Thiourea at 500 ppm increased the GDD required for physiological maturity, HTU required for flower initiation and protein content in soybean as compared to the control. Foliar application of Thiourea at 1000 ppm (T5) increased the number of days required for seed filling duration (0.63 days) and also delayed field maturity as compared to the control. It also increased crop growth rate at 30 45 DAS, photosynthetic rate, transpiration rate, plant height at 75 DAS, and fiber content as compared to the control. Foliar application of Cycocel at 100 ppm (T6) and Salicylic acid at 500 ppm (T2) increased the phenothermal index required for pod formation and no. of branches plant-1. Foliar application of IBA at 200 ppm (T7) increased total dry matter accumulation (g plant-1) at 75 DAS, leaf area at 30 DAS and 45 DAS, leaf area index at 30 DAS and 45 DAS; leaf area duration at 30 45 DAS and at 45 75 DAS. newline newline newline newline