Thermal requirement of wheat crop in different agroclimatic regions of Punjab under climate change scenarios

Abstract

The experiment was conducted at two zones of the Punjab state (i.e., Central plain zone, Ludhiana and South-Western zone, Bathinda) to study the phenological behaviour of wheat cultivars under different environments. The two wheat varieties, viz., V1: PBW 343 and V2: PBW 621, were evaluated under three sowing dates (D1: November 15, D2: November 25 and D3: December 5) and four irrigation levels I1 (irrigation at CRI, Jointing and Milking), I2 (irrigation at CRI, Tillering, Booting and Milking), I3 (irrigation at CRI, Tillering, Jointing, Booting and Milking) and I4 (irrigation according to weather forecast) during rabi 2011-12. The Growing Degree Days (GDD), Heliothermal units (HTU), Photo thermal units (PTU) and Heat use efficiency (HUE) were calculated. It was found that the wheat crop sown in central zone i.e., Ludhiana station acquired more number of days to reach physiological maturity and utilize heat more efficiently resulting in more grain yield as compared to south western zone i.e., Bathinda station grown wheat crop. The results also showed that the variety PBW 621 took significantly less time for initiation and completion of the various phenological stages than PBW 343. PBW 621 acquired less growing degree days, heliothermal units and photothermal units but was more efficient user of heat as compared to the variety PBW 343. The number of days required to attain different phenological stages decreased with late sowing condition. Irrigation levels failed to produce significant difference for days required for initiation and completion of various growth stages of crop as well as heat unit requirements for occurrence of the phenological events. It is concluded that timely sown crop exhibit best growth and yield as the favourable environmental conditions coincided with heat unit requirement of different phenophases of wheat in the central zone of Punjab.