Soybean Physiology and Yield Response to Seed Rate and Sowing Method

Abstract

The soybean crop is highly sensitive to climate change associated events viz., global warming, drought, and water-logging at the time of highly sensitive flowering and grain filling stage, causing a shortfall in production and supply of quality seed to the country. Under prevailing high-density planting, at the seed rate of 70 kg ha-1 and flatbed sowing method, plant growth is restricted due to limitation of radiation and nutrients. Hence, the seed rate and sowing method need revision in an era of climate change. Therefore, we hypothesized that adopting a lower seed rate under ridges and furrow sowing would improve seed yield and quality over the prevailing seed rate of 70 kg ha-1 and flatbed sowing method. In order to test our hypothesis, an experiment was conducted to study the effect of various seed rates and sowing methods on growth and productivity of soybean. Studies revealed that a seed rate of 70 kg ha-1 shows superiority in terms of seed yield (3873.70 kg ha-1) which was at par with 60 kg ha-1 (3359.40 kg ha-1). Lower seed rate of 60 kg ha-1 was superior in terms of seed yield per plant (8.99 g plant-1), biological yield (6310 kg ha-1), Harvest index (35.69%), dry matter accumulation in pods at 61 DAS (1.74 g). Ridges and furrow sowing method was found superior for biological yield (26.33 g plant-1) and (6958.90 kg ha-1), dry matter accumulation in pods at 61 DAS (1.84 g), Leaf Area Duration at 71 DAS (19535.00 cm2.days). Interaction studies revealed that 60 kg ha-1 seed rate with ridge and furrow stand superior in terms of seed yield per plant 10.65 g plant-1 which was attributed to maximum harvest index (29.58%), dry matter accumulation in pod at 61 DAS (2.13 g), Leaf Area Duration at 71-81 DAS (22069.00 cm2.days). In contrary, highest seed yield(4018.89 kg ha-1) was observed for seed rate of 70 kg ha-1 with flat bed sowing. Hence it can be concluded that, under low productive environment the efficient dry matter accumulation, leaf area development and number of branches under low density planting will not compensate for the higher plant stand induced yield increment due to high density planting. Therefore, higher seed rate of 70 kg/ha with ridge and furrow sowing will be recommended to the farmers to get higher yield of soybean under rainfed and low productive environment.