Evaluation of Tomato Landraces for Tolerance to Drought Stress Using Morphological and Physiological Traits

Drought is among the stress factors that, on a global scale, have direct negative effects on plant growth, yield, and quality. Great efforts are directed towards water shortage adaptation. Exploring the genetic diversity of landraces often tolerant to locally occurring stress can represent a valuable source for the development of cultivars with yield stability and improved quality under stress conditions. This study aimed to identify drought-tolerant tomato landraces based on an integrated approach involving morphological traits and physiological parameters. To investigate the effects of water deficit, five landraces and two controls were tested under optimum and 50% reduced irrigation. Yield and yield-related traits, color, firmness, and chlorophyll fluorescence measurements were evaluated. The summarized results indicated that the tomato landraces differed in their responses to water deficit. Water deficit decreased the yield by 44% and the average fruit weight by 29%. Physiological parameters were also significantly affected by water scarcity, with a decrease in the ratios Fv/Fm (the maximum quantum yield of PSII) and Fv/Fo (the maximum primary yield of photochemistry) of 8.2% and 35.5%, respectively, at 14 days’ exposure to stress. Landrace 1352, characterized by indeterminate growth habit and large, rounded, and red-colored fruits, showed a significantly lower reduction in yield and physiological parameters under reduced irrigation and could be used in breeding programs to develop new tomato lines combining resistance with quality.