Effect of Weather Indices under Different Sowing Windows on Grain Yield of Sorghum

Background: Sorghum (Sorghum bicolor L. Moench) is one of the major staple cereal crops after rice and wheat. Photoperiod (day length) sensitivity has been shown to affect the duration of plant’s vegetative phase based on sowing dates. Optimum sowing date is one of the most important factors that play an important part in yield. Methods: A field experiment was carried out during the summer season of 2022. in the Eastern block farm (37F) of Tamil Nadu Agricultural University, Coimbatore in sandy loam soil to study the phenological behaviour of sorghum as influenced by sowing window (D1 - First fortnight of February, D2 - First fortnight of march and D3 - First fortnight of April) by analysing the Helio-thermal units (HTU), Photo-thermal units (PTU) and growing degree days (GDD) and to evaluate the performance of sorghum CO-32 cultivar. The experiment was laid out in strip plot design. Results: Among the different sowing windows highest grain yield was recorded when sowing was done in I FN of April (2602.81 kg/ha) followed by I FN of March (2484.53kg/ha). The attainment of phenophases was found early in February sowing. It was observed that accumulated heat units increased by 114 °C and 142.2 °C days in March and April sown crop compared to February sown crop. Among the sowing windows maximum photo thermal units were accumulated by April sown crop (15135.2oC day hrs) followed by March (13485.57oC day hrs) and February (11608.5oC day hrs) sown crop respectively.