Phenology, productivity and energy utilization of wheat as influenced by hydro-thermal regimes in central Punjab

Response of wheat to sowing dates and irrigation regimes was studied at Punjab Agricultural University, Ludhiana during Rabi 2016–17 and 2017–18 for assessing phenological development, heat unit accumulation and their cumulative effect on wheat yield. Both sowing dates and irrigation regimes have marked influence on number of days taken to attain various phenological stages, heat unit accumulation viz., growing degree days (GDD), helio-thermal (HTU) and photothermal (PTU) units in pooled analysis. Wheat sown on 25^th October took maximum calendar days to attain various phenophases starting from tillering to maturity and accumulated highest GDD, HTU and PTU, which further gets reduced with subsequent delay in sowing time. October 25^th sown wheat also resulted in maximum grain yield (5456+631 kg ha⁻¹), which was non-significant with 5^th November but significantly higher than 15^th and 25^th November sowing. Among irrigation regimes, crop irrigated at 1.25 IW:CPE exhibited highest GDD, HTU, PTU and resulted in maximum grain yield. Thus, wheat sown on October 25 and irrigated at 1.25 IW:CPE was found to be the most efficient in terms of highest grain yield and maximum thermal use efficiencies.