Phenotypic characterization of wheat germplasm for heritability and dissection of association among post anthesis traits under variable sowing dates

Background: The world's main crop for producing staple foods is wheat. In South Asia's cotton-wheat cropping system, however, a late cotton harvest causes a delayed wheat planting, which causes significant production losses. Therefore, this study investigated genetic diversity among wheat genotypes for late sowing. Additionally, associations between several yield-related parameters were discovered, along with their direct and indirect implications on the choice of the best genotypes suitable for late planting. Methods: Twenty wheat genotypes/advance lines were evaluated under two sowing times, i.e., normal sowing and late sowing for two consecutive years (2019–2021). Data regarding post anthesis traits were collected. Results: The findings showed that planting dates and genotypes substantially (p < 0.05) impacted all characteristics. Genotype ‘9622’ proved consistent for grain yield by showing the lowest reduction under late sowing. Similar to this, assessments of heritability, correlation, and path coefficients showed that heredity and association strength varied with various sowing dates. Number of spikelets per spike, spike length and biological yield showed the highest correlation and direct and indirect effects on grain yield. Association among traits, and the performance of different genotypes under normal and late sowing was also confirmed by biplot analyses, which grouped the genotypes based on their variation for different traits. Conclusion: In conclusion, late sowing reduced yield and changed association among the studied traits, probably due to terminal heat stress. Therefore, selection criteria must be evaluated separately in selecting genotypes adoptable to late sowing and other varying environmental conditions.