Induction of water stress in major Solanum crops: A review on methodologies and their application for identifying drought tolerant materials

The genus Solanum encompasses several economically important vegetable crops, such as tomato, potato, and eggplant, which are crucial for ensuring food security. Higher temperatures and reduced precipitation are becoming more frequent due to climate change in numerous regions, fostering drought spells and the likelihood of water stress in Solanum crops resulting in decreased yields. Appropriate evaluation techniques are required by researchers and breeders to evaluate the impact of drought on the performance of Solanum crops and identify more tolerant genotypes. This review examines the most important approaches for inducing water stress in Solanum crops, such as withholding irrigation, adjusting field capacity levels, applying evapotranspiration criteria, and utilizing polyethylene glycol as an osmotic agent. We highlight the benefits and drawbacks of each method, enabling researchers and breeders to choose the most suitable conditions for their specific objectives and goals. Additionally, we address the challenges of combining water stress with other types of stress that frequently occur simultaneously in the field and the effects that biostimulants can have in mitigating water stress in Solanum crops. We also provide an in-depth analysis of the impact of water deficit on growth and biomass, as well as on physiological and biochemical traits, and new phenotyping tools that allow the study of stress tolerance in the three major crops belonging to the Solanum genus. Finally, the review discusses the possibility of utilizing wild species to improve water stress tolerance in these Solanum crops.