EVALUATION OF SUNFLOWER GENOTYPES FOR YIELD AND PHYSIOLOGICAL TRAITS UNDER WATER STRESS CONDITIONS

Abstract

Water stress is an important constraint affecting sunflower growth, physiological traits and yield. The present study was conducted to evaluate the mean performance and variability of sunflower genotypes for morphological and physiological traits under contrasting irrigation regimes. The experiment was conducted during the Rabi season of 2023 at the Oilseeds Research Institute, Agriculture Research Center, Tandojam, using 11 sunflower genotypes comprising three lines, two testers and six F1 hybrids. The experiment was laid out in a split-plot design with three replications, with irrigation regimes assigned to main plots and genotypes to sub-plots. Two irrigation treatments, normal irrigation and water stress imposed at the initial and flowering stages, were evaluated. Data were recorded for days to 90% maturity, plant height, number of leaves plant⁻¹, leaf area, head diameter, stem girth, number of seeds head⁻¹, seed index, seed yield, relative water content, chlorophyll content and oil content. Analysis of variance revealed significant differences among genotypes for several morphological and physiological traits, indicating considerable genetic variability. HO-1 × PSF-05 showed superior performance for head diameter, stem girth, seed index and seed yield, whereas HO-1 × Corolla exhibited higher leaf area and number of seeds head⁻¹. PSF-05 showed desirable performance for early maturity and oil content. Genotypic responses varied between normal and water-stressed conditions, particularly for seed index, relative water content and chlorophyll content. The identified superior genotypes may serve as valuable material for developing sunflower cultivars with improved performance under water-limited conditions.