Physiological Screening of Drought Tolerance in Sesamum indicum L. Based on Leaf Water-Holding Capacity across Phenological Stages

Abstract

The study evaluates the leaf water-holding capacity of 12 Sesamum indicum L. accessions of diverse geographical origin under rainfed conditions in the Tashkent region. Measurements were performed in three phenological stages (bud formation, flowering, seed maturation) using the gravimetric method. The flowering stage was identified as the key diagnostic period for drought tolerance, showing the greatest variation in water-holding capacity among genotypes. Based on the minimum water-holding capacity (S) and its phase variability (Δ), four drought tolerance classes were distinguished. Accession K216 (Syria) demonstrated stable water-holding capacity and was classified as highly tolerant; K9549 (India) and K1185 (Tajikistan) were identified as near-tolerant and are recommended as donors for breeding. K1396, K598, K9428 and the control cultivar Tashkentskiy-122 exhibited high sensitivity to water deficit. The most drought-tolerant accession (K216) maintained water-holding capacity above 62% during flowering, whereas sensitive lines dropped below 48%, confirming the diagnostic relevance of this indicator. The phase dynamics of water-holding capacity proved to be an informative physiological marker for rapid drought tolerance screening in sesame. The obtained results highlight the value of water-holding capacity -based physiological screening for identifying drought-tolerant sesame genotypes suitable for use in breeding programs.