Abstract

                                An investigation was carried out to study the morphological and physiological mechanisms involved in the differential response of the sunflower genotypes to water stress. Water stress was imposed at early (45 to 60 days after sowing) and late (65 to 80 days after sowing) stages of plant growth. Various morophophysiological parameters viz. plant height, leaf area, leaf expansion rate, RWC, LWP, leaf membrane integrity, stomatal diffusive resistance and transpiration rate were studied. Among the genotypes, TNAUSUF 205, CO 4 and RHA 272 recorded more plant height, leaf area, leaf expansion rate, RWC and LWP and also recorded low leakage of solutes, less transpiration rate with high stomatal diffusive resistance under both the stress situations. This study has demonstrated the interplay of morphological and physiological adjustment that enabled sunflower to survive under conditions of water stress with less reduction in grain yield.

Key words : Water stress, Leaf area, Leaf expansion rate, Relative water content, Leaf water potential, Leaf membrane integrity, Stomatal diffusive resistance, Transpiration rate.