Symptom expression and severity indices of Solanum lycopersicum L. and Solanum melongena L. at different growth stages under water deficit

Abstract

A screenhouse trial was conducted during the dry season of 2020–2021 to evaluate expression of drought-induced symptoms of Solanum lycopersicum (tomato) and Solanum melongena (eggplant) cultivars and assess their severity indices at different growth stages in response to limited water supply. This was aimed at identifying growth stages at which water deficit is most severe and provide a reliable and more efficient approach to mitigate drought stress in S. lycopersicum than S. melongena. The trial was laid out in a complete randomized design under four watering treatments; Control: subjected to water deficit at all growth stages; W1: subjected to water deficit at vegetative stage; W2: subjected to water deficit at flowering stage; W3: subjected to water deficit at fruiting stage, with six replications. Emerging symptoms were evaluated on whole plants, stems, and leaves, and severity indices were determined based on the occurrence of the symptoms and plants affected. This finding showed that symptoms such as stem lesion, chlorosis, leaf scorch, leaf abscission, and wilting in S. lycopersicum and S. melongena were exhibited at varying degrees during different growth stages. The severity of S. lycopersicum and S. melongena was highest at flowering stage (81.67 and 73.33% respectively) compared to vegetative and fruiting growth stages. Thus, mitigating water deficit in S. lycopersicum and S. melongena at flowering stage will provide valuable insights for drought tolerance breeding studies in both species via practices such as targeted irrigation or irrigation scheduling.