Thermal variations in pigeonpea genotypes with change of growing environment in semi-arid regions of India

Time of sowing is one of the most important agronomic factors for realizing the potential yield of the crop. The field experiment was conducted at RARS, Vijayapura, during Kharif 2021. The experiment was laid out in a split-plot design assigning four sowing windows to main plots viz., first fortnight of June (23-24^th Standard Meteorological Week), second fortnight of June (25-26^th SMW), first fortnight of July (27-28^th SMW) and second fortnight of July (29-30th SMW), whereas genotypes to subplot viz.,TS-3R, GRG-152 and GRG-811 and replicated thrice. The early sown pigeonpea accumulated higher GDD, PTU, HTU, PTI, HUE, PTUE and HTUE at different phenophases. However, accumulated heat units and thermal efficiencies decrease with delay in sowing. The results revealed that the phenophase 50% podding to physiological maturity recorded higher heat unit and thermal efficiencies among all the phenophase. The total GDD required for crop growth was higher in first fortnight of June sowing (3209.2 0C days). Genotype differed significantly for GDD accumulation where, GRG-811 accumulated more GDD (3114.4 0C days) compared to other two genotypes GRG-152 (3096.0 0C days) and TS-3R (2867.8 0C days). Similarly, early sown pigeonpea recorded more PTU (38430 0C day hrs), PTI (120.47 0C days day^-1) and HTU (16540 0C day hrs). Among the genotype GRG-811 recorded higher PTU (37308 0C day hrs) and HTU (16095 0C day hrs). However, TS-3R recorded higher PTI (119.77 0C days day^-1). The correlation studies revealed that heat units showed non-significant and positive correlation with seed yield wherein, it showed highly significant (p≤0.01) and positive correlation with biological yield except PTI which showed non-significant correlation with biological yield. Likewise, thermal efficiencies showed highly significant (p≤0.01) and positive correlation with seed yield and significant (p≤0.05) and positive correlation with biological yield. Which means the temperature and sunshine hours significantly influenced the seed yield and biological yield.