Influence of growth stage specific water stress on the yield,physico-chemical quality and functional characteristics of tomato grown in shallow basaltic soils

Abstract

tVarious options of deficit irrigation (DI) were tested for accumulation of functional food compounds ontomato included; (i) continuous deficit irrigation i.e. applying irrigation water equally (0.6, 0.8 and 1.0evapotranspiration (ET)), (ii) DI at vegetative, flowering and fruiting stages (0.6 ET for 30 days), (iii) DIat vegetative and flowering, vegetative and fruiting, flowering and fruiting stage (0.6ET for 30 days ateach stage) and (iv) withholding of irrigation at vegetative, flowering and fruiting stage for 15 days.Fruitquality and functional food properties improved with DI. Color (a/b* ratio) and the concentrations ofvitamin C increased by 82 and 70% with irrigation of 0.6 ET continuous DI compared to control. With-holding irrigation during fruit development induced color development (52%), vitamin C content (16%)and recorded better lycopene content (10.2 mg/100 g). The total phenolics and flavonoids ranged between16 and 42 mg gallic acid equivalent/100 g and 4–10 mg catechin equivalent/100 g respectively with highervalues recorded under DI at fruiting stage. Antioxidant activity (AOA) tested with different in vitro assaysrevealed the positivity of DI on improvement of bioactive compounds. Superoxide dismutase activity wassignificantly higher in DI treatments at fruiting stage compared to catalase activity. DI or withholdingirrigation at fruiting stage could improve the quality of tomato due to redox oriented homeostasis ofbiologically active compounds and their biosynthesis.