Physiological and agronomic characterization of sunflower grown under controlled and field environment reveals differential responses to contrasting soil moisture conditions

Abstract

Water stress is one of the main factors affecting the growth and productivity of sunflowers. In this study, we conducted assays under controlled laboratory conditions with plants in the vegetative growth stage (V8) or in the field with plants at reproductive stage (R9) to evaluate various parameters of six sunflower inbred lines grown with or without water stress. The laboratory assay assessed the effects of water stress on morphological (leaf area, fresh and dry biomass), physiological (stomatal conductance and leaf water potential), and biochemical (total soluble sugars and photosynthetic pigments) parameters. In the field assay, the seed yield and its components along with seed quality traits were evaluated. In laboratory, the water stress treatment was imposed by irrigation suppression when the eighth leaf reached 40 mm in length. In the field, the soil was covered with polyethylene sheets to avoid the entry of precipitation, which generated water stress of 38% of the field capacity of the soil. All inbred lines showed a decrease in most parameters evaluated in laboratory when subjected to water stress. In field, the relative number of seeds per/head was the parameter most affected by this stress. The parameters relative shoot and root dry weight, relative water potential, relative oil yield, relative seed yield, and the relative number of seeds per/head enabled us to classify the inbred lines as tolerant, intermediate, and sensitive to water stress. Our findings position B71 as a valuable parental line, while noting that complementary genomic analyses could strengthen breeding applications.