Genetic Analysis of Quantitative Traits in Maize: Evaluation of Diallel Crosses for Normal and Delayed Growth Using Various Stress Tolerance Indices

This study highlights the importance of general and specific combining abilities in maize breeding, emphasizing genotype-by-environment interactions. The findings revealed superior hybrids with enhanced stress tolerance, demonstrating the potential for developing high-yielding, resilient maize varieties adaptable to varying environmental conditions. Early sowing significantly improves vegetative growth and yield components, making it a key factor for enhanced maize production. Genetic variability among genotypes revealed substantial differences in performance, emphasizing the need for diverse parental lines in breeding programs. The study also found that non-additive genetic effects play a crucial role, highlighting the potential of hybrid breeding, especially through heterosis, to increase maize yield and stress tolerance. The hybrid P3×P8 demonstrated the highest heterotic effect (304.71%) relative to mid parent and superiority over SC 168 by 8.71, 19.29 and 13.64% at early, late planting dates and combined across them, respectively, making it the most promising candidate for commercial release. These findings suggest that multi-environment testing is necessary to identify stable hybrids across different planting conditions. Overall, the results indicate that P3 and P7 are promising parents for yield improvement due to their positive contributions to key agronomic traits. Genotypes P3xP8, P1xP3, P2xP7, P6 and P7, exhibited superior stress tolerance as evidenced by their higher STI, GMP, TOL, and YI values.