Impact of modified microclimate on the performance of Green gram (Vigna radiata L.) under different planting systems in the Upper Brahmaputra Valley zone of Assam

Aim: To study the impact of modified crop microclimate on the performance of green gram in a representative district of the Upper Brahmaputra Valley zone ofAssam. Methodology: A field experiment was conducted during the summer of 2021 in the ICR Farm of Assam Agricultural University, Jorhat to study the impact of modified microclimates on the growth and yield of green gram under different planting systems. The variety SGC-16 was grown in a split-plot design with 3 dates of sowing at an interval of 15 days starting from 20 th February (D 1 1) till 20 March (D ) in main plots and three planting th 2 sowing (D2):06.03.2021 nd P P2 3 systems, i.e., P 1 1- ridge and furrow, P - raised bed with two rows rd 2 3 sowing (D 3 3):20.03.2021 P3 in bed and P 3 3-flat bed in sub-plot treatment, with three replications following recommended agronomic practices. Main plot (Dates of sowing) Sub plot (Planting System) Results: The average soil moisture content in the upper 30 cm soil profile was highest in D 3 (80.4 +/- 11.8 mm), followed by D 2 (75.0 +/- 7.8 mm) and D 1 (66.4 +/- 6.9 mm). Compared to P , the 3 decrease in weekly evening soil temperatures under P 1 and P2 was up to 2.1 and 1.4 degrees C, respectively. Irrespective of sowing dates the mean maximum leaf area index (2.06) and higher pods per plant (16.7) were recorded under P 1 1. The seed yield under different sowing dates and planting systems ranged from 286.3 to 681.0 kg ha with an overall mean of 509.8 kg ha .-1-1 Correlation studies between seed yield, LAI and soil moisture in th the upper 30 cm soil profile confirmed the existence of a Highest seed yield of crop sown on 20 March (D 3 3) significant and positive correlation between them. under raised and furrow planting (P 1 ) Interpretation: The yield of the crop planted on 20th March (D 3 3) under ridge and furrow planting (P ) was maximum, facilitated by optimum weather th conditions with improved soil hydrothermal regimes at various phenological stages of entire crop growing season.