Drought and heatwave affected the African eggplant differently when present in combination than individually

Heat waves and drought periods are set to happen more often due to a changing climate, especially in Africa. The African eggplant, Solanum aethiopicum L., is a highly nutritious vegetable crop indigenous to Africa commonly grown by small-holder farmers. It is adapted to harsh environments but empirical data on its tolerance to high temperatures and drought individually or in combination to help farmers is lacking. This project aimed to describe the effects of drought in combination with heat waves on the leafy African eggplant Shum E11 genotype over 26 days of stress. Four-week-old plants were subjected to repetitive heatwave-type stress consisting of eight days of day/night temperatures reaching 32/26 °C or 37/31 °C compared to 27/21 °C, followed by four days of recovery, repeated twice. A drought treatment was applied during the experiment by maintaining the soil water potential at − 100 kPa compared with − 10 kPa for non-stressed plants. Drought stress had a predominant effect over heat by reducing leaf production and leaf membrane stability and increasing chlorophyll content. Antioxidants and phenols were unaffected by drought or heat stress while mineral elements were impacted differently by each stress and their combination. These results indicate a good tolerance of the E11 genotype to heat stress during the vegetative stage while drought negatively affected plant growth and leaf biochemical compounds. Further research on later developmental stages will complete our understanding of this variety's tolerance to heat and drought and its potential role in fields affected by environmental stresses