Genetic characterization of bread wheat (Triticum aestivum L.) for seed yield and its attributing traits under late sown cropping condition

Introduction

Wheat (Triticum aestivum L.) is one of the most important cereal crops of the world and serves as a staple food for a large proportion of the global population. Belonging to the family Poaceae, wheat is cultivated across diverse agro-climatic regions ranging from temperate to subtropical environments. Globally, wheat occupies about 220-225 million hectares with an annual production exceeding 780 million tonnes and an average productivity of around 3.5 t ha⁻¹, making it one of the leading cereal crops alongside rice and maize (Mohan et al., 2022) [6] . In India, wheat is the second most important food grain after rice and plays a pivotal role in ensuring national food security. It is cultivated on approximately 31-32 million hectares with a production of about 110-112 million tonnes and an average productivity of nearly 3.5 t ha⁻¹. The major wheat-growing states include Punjab, Haryana, Uttar Pradesh, Madhya Pradesh, Rajasthan and Bihar, contributing substantially to the national grain pool. Nutritionally, wheat is a rich source of carbohydrates (about 60-70%), moderate protein content (10-14%), dietary fiber, vitamins (particularly B-complex vitamins such as thiamine and niacin), and essential minerals including iron, zinc and magnesium. Wheat gluten proteins impart unique viscoelastic properties to dough, making it highly suitable for a wide range of food products such as bread, chapati, pasta, biscuits and other bakery products. Economically, wheat contributes significantly to farmers' income, rural employment and agro-based industries. It plays a crucial role in public distribution systems and buffer stock maintenance, thereby stabilizing food prices and ensuring food availability. Despite remarkable yield gains achieved during the Green Revolution, spearheaded by the introduction of semi-dwarf varieties, sustaining and enhancing wheat productivity under changing climatic conditions and increasing biotic and abiotic stresses remains a major challenge. In this context, the assessment of genetic variability among wheat genotypes is of paramount importance. Genetic variability provides the basic material for selection and crop improvement. A thorough understanding of the magnitude of variability, heritability and genetic advance for yield and yield-attributing traits helps breeders to identify characters governed predominantly by additive gene action and amenable to effective selection (Zewdu et al., 2023) [9] . Yield in wheat is a complex quantitative trait influenced by several interrelated component traits such as days to heading, days to maturity, plant height, number of tillers per plant, spike length, number of grains per spike and test weight. Therefore, correlation and character association studies are essential to determine the nature and extent of relationships among these traits. Such studies facilitate the identification of traits that have a strong positive association with grain yield and can be used as indirect selection criteria in breeding programmes. Furthermore, the evaluation and genetic characterization of diverse wheat genotypes enable the identification of superior performing lines possessing desirable combinations of traits. These elite genotypes can be directly recommended for cultivation after multilocational testing or utilized as potential parents in hybridization programmes aimed at developing highyielding, stable and climate-resilient wheat varieties. In view of the above considerations, the present investigation entitled "Genetic Characterization and Character Association Studies in Wheat (Triticum aestivum L.) Genotypes for Yield Attributing Traits" was undertaken to assess the extent of genetic variability, analyze the association among yield and its component traits, and identify promising genotypes that could be effectively exploited in future wheat breeding programmes for yield enhancement and stability.

Materials and Methods

The present investigation was carried out at the research farm of FASAI, Rama University, Mandhana, Kanpur-209217 during rabi 2025 under late sown condition. For experiment purpose 104 diverse wheat genotypes (Table 1.) were collected and evaluated in augmented block design with four check entries. All the recommended agronomic practices have been followed to raise the good crop. Data for all important traits related to yield parameters such as Days to 50% flowering (DFF), Days to maturity (DTM), Plant height (cm) (PHT), Tillers per plant (TPP), Spike Length (cm) (SL), Peduncle Length (PL) cm, Spikelet per spike (SPP), Grains Per Spike (GPS), Grain weight Per Spike (GWPS), Test Weight (TW) g., Biological Yield Per Plant (BYPP), Seed Yield Per Plant (SYPP) g., and Harvest Indesx (HI %) have been recorded by tagging five randomly selected competitive plant. Mean of the recorded data for each trait were calculated and subjected to statistical analysis to investigate the factful result.

Results and Discussion

Analysis of Variance

The analysis of variance revealed highly significant differences among the 104 wheat genotypes for all thirteen traits studied, indicating the presence of substantial genetic variability for yield and its component characters (Table 2.). Treatment mean squares were significant at both 5% and 1% levels for traits including days to heading, days to maturity, plant height, effective tillers per plant, spike characters, grain weight, 1000-grain weight, biological yield, grain yield per plant and harvest index, demonstrating wide variation among genotypes. The genotype component was highly significant for almost all traits, suggesting good scope for selection and genetic improvement. The significant differences observed between checks and genotypes for most yield-related traits further indicate the superiority or distinctiveness of certain experimental lines over standard varieties. The relatively low and mostly nonsignificant block effects, along with smaller error variances compared to treatment variances, confirm the reliability and precision of the experiment. Overall, the results highlight ample exploitable variability for effective selection in wheat breeding programmes.

Genetic Variability parameters estimate

The estimates of genetic variability parameters among 104 wheat (Triticum aestivum L.) genotypes revealed substantial variation for yield and its component traits. Days to 50 per cent heading recorded a mean of 78.5 days (range: 66.2-89.2) with high heritability (96.3%) and high genetic advance as per cent of mean (98.7%), indicating strong additive gene action (Dave et al. 2021). Similarly, number of grains per spike (mean: 52.88; range: 31.6-74.2) exhibited high GCV (16.93%), PCV (17.75%), heritability (91.52%) and high GAM (93.92%), suggesting excellent scope for selection. Grain weight per spike showed the highest variability with GCV (21.26%) and PCV (22.69%), along with high heritability (88.31%) and GAM (90.71%). Peduncle length (mean: 37.66 cm; range: 22.67-61.9 cm) also expressed high GCV (17.12%), heritability (90.17%) and GAM (92.57%). The 1000-grain weight (mean: 43.22 g; range: 32.08-52.51 g) exhibited high heritability (94.22%) with moderate GCV (10.33%) and high GAM (96.62%). Grain yield per plant (mean: 15.73 g; range: 11.67-22.96 g) (Prasad et al. 2020) showed moderate variability (GCV 12.08%, PCV 16.35%) and moderate heritability (52.75%), indicating the influence of both genetic and environmental factors. In contrast, harvest index (mean: 35.78%) showed low heritability (18.18%) and low GAM (20.58%), reflecting greater environmental influence. In general, PCV values were slightly higher than GCV for all traits, indicating limited environmental effects. The presence of high heritability coupled with high genetic advance for key traits such as grains per spike, grain weight per spike, peduncle length and 1000-grain weight (Donga et al. 2022) suggests that these characters can be effectively utilized as selection criteria for yield improvement in wheat breeding programmes.

Correlation studies among 13 most important yield attributing traits

The genotypic (rg) and phenotypic (rp) correlation analysis among 13 traits revealed that genotypic correlations were generally higher in magnitude than phenotypic correlations, indicating strong inherent genetic associations with comparatively lower environmental influence. Grain yield per plant (SYPP) exhibited significant and positive genotypic correlations with grain weight per spike (0.600**), test weight (0.902**), harvest index (0.48**), and number of effective tillers per plant (0.274**), indicating these as major direct yield-contributing traits. At the phenotypic level, SYPP (showed strong positive associations with grain weight per spike (0.404**), test weight (0.553**) (Mekaoussi et al. 2021) [5] , biological yield per plant (0.657**) and harvest index (0.61**) (Alemu et al. 2020) [1] , suggesting their practical importance in selection programmes. Number of grains per spike was highly and positively correlated with grain weight per spike at both genotypic (0.773**) and phenotypic (0.711**) levels, reflecting the interdependence of sink components. Plant height also showed positive association with SYPP at the genotypic level (0.261**), whereas harvest index maintained a consistent positive relationship with yield. Conversely, some traits such as spikelets per spike (Regar et al. 2023) [8] and certain phenological traits showed weak or negative associations with yield, indicating limited direct contribution. Overall, the results suggest that effective tillers per plant, grain weight per spike, test weight and harvest index are key yield-determining traits and can be emphasized in selection strategies for yield improvement in wheat.

Conclusion

The study identified several key yield-contributing traits with high genetic potential and practical breeding value. Grain weight per spike exhibited high variability (GCV 21.26%, PCV 22.69%), high heritability (88.31%) and strong positive genotypic correlation with grain yield per plant (0.600**), indicating its major direct contribution to yield and suitability for direct phenotypic selection. Number of grains per spike (mean 52.88; heritability 91.52%; rg with grain weight per spike 0.773**) also showed high genetic control, suggesting that improving sink capacity would substantially enhance yield. Test weight (1000-grain weight) recorded high heritability (94.22%) and very strong positive genotypic correlation with grain yield (0.902**), making it a reliable and stable selection criterion. Peduncle length (heritability 90.17%; GAM 92.57%) demonstrated high genetic advance, indicating additive gene action and its usefulness in selecting vigorous and high-yielding genotypes. Additionally, number of effective tillers per plant showed positive association with grain yield (rg 0.274**), emphasizing its importance in improving yield per unit area. In contrast, harvest index showed low heritability (18.18%), suggesting greater environmental influence and limited effectiveness of direct selection. Overall, traits with high heritability, high genetic advance and strong positive correlation with grain yield-particularly grain weight per spike, number of grains per spike and test weight-should be prioritized as key selection indices in future wheat breeding programmes aimed at developing high-yielding, stable and genetically superior cultivars.

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