A comparative study of morpho-physiological responses of wild and cultivated Solanum species to water stress: the case of S. sisymbriifolium and S. macrocarpon

Crop wild relatives are closely related taxa of cultivated crops and are well adapted to a wide range of environmental conditions. With the current global warming and challenges in agriculture and food production, increasing attention must be given to these crop wild species as they can provide genetic resources that may be helpful to address some of the current challenges in agriculture (e.g., adaptation to drought). In this study, we compared the morpho-physiological performances of Solanum macrocarpon and its wild relative Solanum sisymbriifolium under different watering conditions in Benin. Seedlings were grown in plastic pots under shade-house and subjected to low, moderate, and high-water supply (i.e., 25%, 50% and 75%, respectively of the pot holding capacity). Parameters related to seedlings growth, biomass allocation and stomatal density were investigated. Descriptive statistics and linear mixed effect models were used for data analysis. Results revealed highly significant differences of morpho-physiological parameters between wild and cultivated Solanum species along the watering gradient. First, seedlings from the wild relative demonstrated higher morphological growth parameters than seedlings of the cultivated species irrespective of the watering level. Second, the wild relative also showed better performances in terms of biomass allocation and number of stomata, regardless of leaves faces and watering level than the cultivated species. Water stress reduced values of morpho-physiological parameters for both wild and cultivated species. Contrary to our expectations, the wild relative instead of being resistant, was found to also be sensitive to water stress. However, it was found to be more tolerant to drought than the cultivated species, and therefore could be considered when selecting rootstocks for crop improvement.