ABSTRACT

Irrigation water stress and low water use efficiency (WUE) or water productivity (WP) both influence crop growth and fruit quality. Therefore, the corresponding relationship between amount of water supply and synthesis of bioactive compounds requires to be understudied. In this regulated deficit irrigation research study, three irrigation treatments were imposed on two commercial garden egg cultivars (Solanum aethiopicum and Solanum gilo) to determine their effects on several plant’s growth and fruit indicators as well as their effects on the phytochemical composition of garden egg fruits. The study was conducted in open field (uncontrolled condition) with the garden egg plants fed solely by rain water, which served as control and in a greenhouse where plants were subjected to three water supply treatments – 100FC, 70FC and 50FC and treatment effects were compared with the control. Antioxidant activity was evaluated using DPPH, FRAP, H₂O₂ and NO assays. Deficit irrigation had no significant effect on some plant growth and fruit yield indicators amongst treatments, but was significant when compared with the control. This suggests that sunlight influences garden egg growth than water supply, as the solar radiation recorded outside the greenhouse was thrice higher than inside the greenhouse. Deficit irrigation significantly increased antioxidant contents in garden egg fruits, but the degree of increment was found to be cultivar-dependent. Overall, the choice of appropriate cultivars subjected to deficit irrigation strategies can significantly influence the bioactive compounds in garden egg, particularly total phenolic contents (TPC) and total flavonoid contents (TFC).