Comparative Assessment of Genetic Variability and Yield-associated Traits in Bread Wheat under Organic and Conventional Production Systems

Abstract

Aims: To assess genetic variability, heritability, genetic advance, and associations among yield and yield-related traits in bread wheat under conventional and organic production systems, and to identify superior genotypes for sustainable wheat breeding. Study Design: A field experiment was conducted using an augmented block design. Place and Duration of Study: The Experimental Farm, Department of Genetics and Plant Breeding, and the Zero Budget Natural Farming Farm, Department of Organic Agriculture and Natural Farming, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, Himachal Pradesh, India, during the rabi season of 2021–22. Methodology: A total of 192 bread wheat (Triticum aestivum L.) genotypes, comprising 186 germplasm accessions and six check varieties, were evaluated under conventional (E1) and organic (E2) production systems. Eleven agronomic and yield-related traits were recorded. Genetic variability was estimated using the genotypic and phenotypic coefficients of variation, broad-sense heritability, and genetic advance as a percentage of the mean, while phenotypic correlation analysis was used to determine associations among traits. Results: Analysis of variance revealed highly significant (P ≤ 0.01) differences among genotypes for all studied traits under both production systems, indicating substantial genetic variability. Phenotypic coefficient of variation values were consistently higher than the corresponding genotypic coefficient of variation values, although the differences were generally small, indicating limited environmental influence on trait expression. Effective tillers per plant under conventional conditions exhibited high broad-sense heritability (95.67%) and high genetic advance as a percentage of the mean (77.31%), while grain yield per plant under organic conditions recorded heritability of 80.51% and genetic advance of 48.85%. This combination suggests that these traits may respond effectively to selection. Grain yield was positively correlated with ear length, spikelets per spike, test weight, and harvest index, whereas days to flowering and plant height showed negative associations. Thirty-six genotypes outperformed the best check under conventional conditions, whereas six genotypes (IC532001, IC542012, EC2990, EC534373, IC138511, and IC0534228) surpassed the best check under organic conditions. Conclusion: Considerable genetic variability was observed among the evaluated wheat genotypes under both production systems. Harvest index, ear length, spikelets per spike, and test weight were identified as useful selection criteria for improving grain yield. The superior genotypes identified under organic conditions constitute valuable genetic resources for developing high-yielding wheat cultivars adapted to sustainable and low-input production systems.