Genetic Parameters and Trait Associations in Wheat Under Drought and Low Nitrogen Conditions

Drought and low nitrogen stress are the leading cause of low crop production and productivity worldwide. Developing drought-tolerant wheat germplasm resilient to low nitrogen conditions is essential through genetic enhancement and selection for novel traits. The objective of the research was to investigate genetic diversity, parameters, and trait relationships within a wheat genotype panel to inform drought- and low-N-tolerant variety selection. This study evaluated 50 wheat genotypes under drought-stressed and non-stressed conditions, with varying nitrogen (50 kg ha−1, 100 kg ha−1, and 200 kg ha−1) levels across four testing sites during the 2019/2020 growing season. Statistical analysis (combined ANOVA) revealed substantial genetic variation (p < 0.05) for the majority of tested traits. High heritability and substantial genetic gain for KPS (97.49%, 28.10% GAM) and SE (96.48%, 14.28% GAM) were determined under drought and low nitrogen stress. Under drought-stressed and non-stressed (at 200 kg N ha−1), grain yield expressed high heritability estimates of 80.43% and 75.68% and genetic advance at 21.90% and 21.56%, respectively. Positive and significant correlations (r > 0.5; p < 0.001) were measured between grain yield and yield components, implicating simultaneous direct and indirect selection of desired traits. The positive relationship between grain yield and yield components suggests that further quantitative trait loci analysis and progeny testing are crucial to guide genotype selection and breeding for drought and low-N stress-tolerant wheat genotypes.