Enumeration of Genetic Variability Parameters and Association among Early Seedling Growth Parameters under Polyethylene Glycol (PEG) induced Osmotic Stress in rabi Sorghum (Sorghum bicolor (l.) Moench)

Abstract

Aims: The research aims to explore the variability within diverse rabi sorghum germplasms and identify the relationships among different early seedling growth traits. This will provide valuable insights for future breeding programs, aiding in the development of resilient sorghum varieties that can contribute to improved food security and agricultural sustainability. Study Design: The study was conducted by employing factorial complete randomized design (FCRD) with two replications. Where, two factors was considered, genotype as first factor and PEG concentration as second. Place and Duration of Study: The experiment was conducted during rabi season of 2023 at University of Agricultural Sciences Dharwad, Karnataka. Methodology: A total of 156 germplasm lines of rabi sorghum were assessed in vitro for early seedling growth characteristics, including germination percentage, shoot length, root length, seedling dry weight, and seedling vigor indices I and II, under both control and osmotic stress conditions induced by polyethylene glycol (PEG). Osmotic stress was induced by dissolving PEG 6000 in distilled water to achieve the desired concentration. The germplasm lines were then subjected to germination and early growth under these conditions using the paper towel method. The genetic variability parameters for each trait were quantified to examine the degree of variability in the material used, and correlation analysis was performed to understand the relationships among the traits studied. Results: The variance analysis showed highly significant differences among genotypes, treatments, and the genotype-by-environment (G×E) interactions. Genetic variability parameters revealed considerable variability across all traits studied, which tended to increase with higher stress levels. Moderate to high GCV and PCV was observed for all the traits studied. Correlation analysis demonstrated a strong, significant positive relationship among all seedling parameters, except between root length and shoot length, as well as between shoot length and germination percentage under control conditions. Conclusion: The study emphasizes the effect of osmotic stress on the early vigor and growth of sorghum seedlings. The findings reveal significant variability in seedling traits, suggesting that selection can be employed for genetic enhancement of these traits. Correlation analysis identified specific traits or combinations of traits that should be considered when selecting genotypes tolerant to osmotic stress conditions. These findings offer great potential to guide and improve selection and breeding programs focused on enhancing drought tolerant sorghum varieties.