Regression Model Based on Thermal Indices and Heat Use Efficiency for Estimation of Pigeonpea (Cajanus cajan (L.) Millsp.) Seed Yield

A field experiment was conducted on experimental farm of Dept. of Agricultural Meteorology, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, Maharasthra, India during the during kharif season 2015 under rainfed condition to find the relationship of pheno thermal and heat use efficiency indices with yield. The field experiment was laid out in factorial randomized bock design with five sowing dates (i.e. 25th, 26th, 27th, 28th and 29th SMW) and three varieties (viz., BDN-711, BSMR-736 and BSMR-853) with three replications. The sowing dates significantly influenced on the phenology, growth, development and yield attributes. The dry spell experienced during sowing to emergence period in first sowing date (25th SMW sowing) and thereafter no rainfall condition during remaining period of sowings viz., 26th, 27th, 28th and 29th SMW, therefore, emergence and final plant count was observed lowest in 25th SMW (30 and 29 %) and highest in 27th SMW sowing (92 %). Hence, significantly highest dry matter plant-1, no. of pods plant-1, seed weight and seed yield plant-1 was observed in 25th SMW sowing; seed yield (417.7 kg ha-1), seed yield heat use efficiency (0.20 kg ha-1 0C day-1) was recorded highest in 27th SMW sowing and lowest in 25th SMW sowing. Significantly highest no. of pods plant-1, seed weight and seed yield plant-1, seed yield heat use efficiency, pheno thermal index was observed in BDN-711 variety and significantly lowest in BSMR-853 variety. The significantly highest total dry matter plant-1 was observed in BSMR-853 and lowest in BDN-711 variety. Significantly highest GDD, HTU and PTU required for completion of different phenophases were recorded in BSMR-736 variety and significantly lowest in BDN-711 variety. Weather indices viz., GDD, HTU, PTU, PTI showed non-significant correlation at all the phenophases with seed yield of pigeonpea. The yield prediction model based on thermal indices and seed yield heat use efficiency at floral bud initiation to 50 % flowering and at 50 % flowering to 50 % pod formation phenophases was found useful in assessing the crop yield one and half to one month in advance.