Studies on Direct and Indirect Effects for Grain Yield and Its Components in Bread Wheat (Triticum aestivum L.)

Abstract

The present study investigates the genetic relationships between various quantitative traits affecting grain yield in wheat, employing a Line × Tester mating design with 22 genotypes to generate 72 F1s and F2s. Wheat is recognized for its rich nutritional profile, providing essential nutrients such as carbohydrates, proteins, vitamins, and minerals.  Path coefficient analysis is a critical statistical tool in wheat breeding, enabling breeders to evaluate complex relationships between traits by measuring their direct and indirect effects on yield. Fourteen traits were evaluated, revealing significant phenotypic and genotypic correlations. The present study was undertaken to assess the direct and indirect effects of fourteen agronomic and physiological traits on grain yield in wheat through path coefficient analysis in both F1 and F2 generations. The analysis was conducted at genotypic and phenotypic levels to identify key yield-contributing traits for effective selection in breeding programs. In the F1 generation, biological weight exhibited the highest positive direct effect on grain yield followed by harvest index, number of tillers, grains per ear, and spike length. Similarly, in the F2 generation, biological weight and harvest index remained the most influential contributors to yield, alongside 1000 grain weight and spike length. Conversely, plant height, days to 50% heading, and days to maturity showed negative direct effects in both generations, indicating their potential as unfavorable traits for yield improvement. The path coefficient analysis across both F1 and F2 generations highlighted biological weight and harvest index as the most reliable traits with strong and consistent positive direct effects on grain yield. The emphasis should be placed on selecting genotypes with high biological weight and harvest index, while cautiously managing traits with negative effects, to develop high-yielding, well-adapted wheat cultivars suitable for future cropping systems.