Effective Selection Criteria for Predicting Thermotolerance in Wheat under Field Conditions

A field experiment was conducted at the experimental area of the Punjab Agricultural University, Ludhiana during Rabi season. Five Wheat cultivars (PBW-343, WH-542, PBW- 502, PBW-509 and PBW-3765) sown on six dates of sowing starting from 31st October at weekly intervals up to 5th December to find suitable thermotolerance traits and genotypes. Amongst eleven traits recorded at different growth stages showed that the largest variability was observed in crop growth rate (CGR), Leaf area index (LAI) grain spike weight ratio (GSPWR), spike growth duration (SGD), cumulative growing degree days (GDD) accumulated during vegetative and reproductive phenophases and grain attributes and grain yield at maturity. The highest grain yield was recorded in Cvs. PBW-343, WH-542 and PBW-502. The maximum grain yield was correlated with longer filling duration, higher crop growth rate and grain spike weight ratio at anthesis phase. The results revealed that the cumulative growing degree-days (GDD) accumulated more during the reproductive phases as compared with the vegetative phases of wheat cultivars. The GDD is the effective selection criteria for screening thermotolerance in wheat cultivars.