PJB-2023-414
GENOTYPIC COMPETITION AMONG WHEAT BREEDING LINES UNDER NORMAL AND LATE PLANTINGS
Muhammad Ibrahim
Abstract
Late planting in wheat is a common practice in rice-wheat cropping system and is one of the crucial yield-limiting factors as a result of terminal heat stress during grain filling. To identify suitable wheat genotypes for late and normal planting, 42 wheat genotypes including 40 advanced lines and two checks were evaluated under normal and late planting conditions. Plant material was sown using a randomized complete block design with three replications at The University of Agriculture, Peshawar during 2021-22 cropping season. Stress selection indices such as tolerance index (TOL), mean productivity (MP), stress tolerance index (STI), trait stability index (TSI) and trait index (TI) were employed to enhance the selection efficiency and identify tolerant wheat genotypes for both dates of planting. Combined analysis of variance revealed significant differences among environment for all studied traits except spike length and harvest index. Similarly, genotypes were also significant for all traits. However, genotype by environment interactions were non-significant for all traits except days to heading and days to maturity indicating consistent performance of wheat genotypes across both environments. Across both test environments, wheat genotype G-25 produced highest grain yield (3704 kg ha-1), followed by G-28 (3426 kg ha-1) and G-35 (3418 kg ha-1). Higher estimates of heritability were observed for days to heading (0.79), plant height (0.91), spike length (0.75), tillers m-2 (0.65), spikelets spike-1 (0.68), grain weight spike-1 (0.71), 1000-grain weight (0.64), biological yield (0.66) and grain yield (0.61) across both planting condition. Correlation analysis revealed that grain yield had significant (p≤ 0.01) association with days to heading, days to maturity, plant height, spike length, spikelets spike-1, grains spike-1, grains weight spike-1, thousand-grain weight, biological yield and harvest index across environments. Based on various stress selection indices, wheat genotype G-25, followed by G-28 and G-35 were suitable across both planting conditions for grain yield and other yield contributing traits. Hence, it could be used in future breeding schemes for the development of heat stress-tolerant wheat genotypes.
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