Response of yield and associated traits of wheat genotypes to temperature fluctuations at Dera Ismail Khan

Wheat is the third largest staple food crop accounting for approximately 4% of cropland and its demand is continuously increasing to feed the growing world population. Average surface temperature and recurrent heat waves are continuously rising from last few decades that adversely influence yield potential of various crops including wheat. Temperature differences can be fashioned by cultivating at diverse planting times. Aim of current investigation was to appraise impact of planting times and thermal high temperature (growing degree days) on yield of 8 cultivars. Crop was exposed to four planting times in wheat crop season 2022-23. Experiment was carried out in randomized complete block (RCB) design with 3 replications. Results revealed that planting times depicted significant variances for all considered yield and associated traits. Similarly, cultivars too exhibited highly significant differences for plant height, physiological maturity, spike length, spikelets/spike, grains/spike, thousand grain weight and grain yield/plant however 50% days to heading and tillers per plant depicted non-significant differences among genotypes. Interaction of planting time to genotypes was also significant for 50% days to heading, days to physiological maturity, spike length, spikelets/spike, grains/spike and 1000 grain weight however it was non-significant for plant height, tillers/plant and grain yield per plant. Cultivar AZRC-Dera produced highest grain yield/plant on account of maximum spikelets, grains spike-1, tillers and thousand grain weight. Highest grain yield was recorded in planting times from 1st November to 20th November due to accumulation of more heat units whereas late cultivation reduced production on account of less accumulation of heat units. Therefore it is determined that wheat should be planted from 1st November to 20th November in Dera Ismail Khan to have good harvest