Study on Agrometeorological Indices and Heat Use Efficiency for Black Gram (Kharif) Crop under Varied Environmental Conditions

An investigation was carried out to determine the optimal sowing time and variety for kharif black gram under rainfed conditions at the AICRP on Agrometeorology farm, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, during the 2023-24 season. A factorial randomized block design (FRBD) was used with three sowing dates (28 MW - 10th July, 29 MW - 17th July, and 30 MW - 24th July) and three varieties (PDKV Black Gold, AKU-15, and AKU-23/5), replicated thrice. Accumulated growing degree days (GDD), helio-thermal units (HTU) and photo-thermal units (PTU) were computed to analyze the crop’s thermal response. The results revealed that crop sown in 28 MW (10th July) recorded the highest GDD, whereas delayed sowing (29 MW and 30 MW) led to reduced thermal accumulation and shortened crop duration. Among varieties, PDKV Black Gold accumulated the highest GDD, followed by AKU-15 and AKU-23/5. Similarly, PDKV Black Gold exhibited the highest HTU, indicating superior adaptability to varying thermal conditions. Yield analysis revealed that crop sown in 28 MW produced the highest seed yield, while delayed sowing (30 MW-24th July) resulted in a significant reduction in productivity. Among the varieties, PDKV Black Gold recorded significantly higher seed yield, straw yield and biomass yield over AKU-15 and AKU-23/5; however, it was at par with AKU-15 in terms of harvest index. Thus, it can be concluded that optimal sowing time for kharif black gram under rainfed conditions is the 28th MW (10th July), as it recorded the highest thermal accumulation (GDD, HTU, PTU) and resulted in the highest seed yield. Delayed sowing in the 29th MW (17th July) and 30th MW (24th July) led to reduced thermal accumulation, shortened crop duration, and lower productivity. Among Varieties, sowing PDKV Black Gold around 10th July is recommended for maximizing productivity under varied environmental conditions in Vidarbha.