Assessing the impact of agro-climatic factors on pod filling of grass pea

Field experiments were conducted for two successive years with grass pea (cv. ‘Prateek’) sown on nine dates at weekly interval at Instructional Farm (22°58´ N, 88°31´ E), Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India to investigate the impact of agroclimatic factors on pod filling of grass pea. Results showed that pod filling percentage (PFP) increased with delay in sowing dates, attaining the highest value (96.7 %) in crop sown on 30th November, beyond which it decreased gradually with further delay in sowing. Maximum and minimum temperatures, morning and afternoon soil temperatures, recorded at 5, 15 and 30 cm soil depths, morning and afternoon vapour pressure deficits at pre-flowering phase exhibited negative association and contrarily, when prevailing during reproductive and pod development phases, these parameters demonstrated positive correlation with PFP. Temperature range during reproductive phase increased with delay in sowing dates and it exhibited significant positive correlation with PFP. As demonstrated by stepwise regression analysis, Accumulated photothermal unit (APTU) prevailing at maturity phase alone accounted for 67.4 % of the total variation in PFP and together with temperature range it explained 91.3 % variation. APTU, temperature range, afternoon vapour pressure deficit and afternoon soil temperature seem to be the critical agroclimatic variables influencing the pod filling percentage significantly.