Leaf morphoanatomical and physiological characteristics of sunflower genotypes under water deficit

Abstract

Sunflower (Helianthus annuus L., Asteraceae) is a drought-tolerant crop whose yield is compromised when there is water scarcity during the flowering period. The objective of the present study was to evaluate, under controlled conditions, the morphoanatomical and physiological aspects of four sunflower genotypes grown under water deficit conditions. The experiment was conducted using a completely randomized design in a 2×4 factorial scheme (two water conditions and four genotypes), with six replicates of one plant per rhizotron pot, totalling 48 plants. The water conditions evaluated included plants under well-watered conditions (field capacity) and plants under water deficit conditions (40 % field capacity). The studied sunflower genotypes included OLISUN03, AGUARÁ06, BRS323, and HELIO250. Water deficit induced developmental delay, reduced shoot and root dry mass, and changed stomatal morphology and density, which were reflected by reduced stomatal conductance, transpiration, and internal CO₂ concentrations. Changes in the areas of intercellular spaces and substomatal chambers, increased collenchyma area and proline leaf content were also observed. It was concluded that the four sunflower genotypes had reduced growth under water deficit, in addition to morphoanatomical changes.