Impact of weather dynamics on radiation use efficiency and biomass accumulation in soybean (Glycine max [L.] Merrill) across its growth stage

An experiment was conducted during Kharif 2024 at the Research Farm of the Department of Agricultural Meteorology, VNMKV, Parbhani to evaluate the influence of different sowing dates and soybean varieties on growth, yield, phenology and radiation use efficiency (RUE) using a line quantum sensor under rainfed conditions. The study was laid out in a split-plot design with four sowing dates (25th SMW to 28th SMW) and three varieties (MAUS-158, MAUS-162, JS-335). Early sowing (D1) significantly enhanced growth parameters, including plant height (25.06 cm), leaf area index (2.5) and dry matter accumulation (17.29 g plant⁻¹). Grain yield was highest in D1 (1969.1 kg ha⁻¹) and decreased with delayed sowing. MAUS-158 outperformed other varieties with maximum yield (1608.8 kg ha⁻¹) and superior RUE (2.40 kg Mj⁻¹) and PAR interception were highest under early sowing and in MAUS-158, indicating efficient use of thermal and radiation resources. Reflected PAR was lowest in MAUS-158, indicating efficient radiation absorption. Results highlight that early sowing in the 25th SMW and selecting MAUS-158 optimize growth, yield, and RUE under semi-arid rainfed conditions. This study emphasizes the importance of strategic sowing time and varietal choice for maximizing soybean productivity through improved radiation and thermal resource management.