Effect of deficit irrigation and storage on the nutritional composition of tomato (Lycopersicon esculentum Mill. cv. Pectomech)

Abstract

The aim of the study was to determine the effects of defcit irrigation and postharvest storage on nutritional composition of tomatoes. Tomato fruits (Pectomech variety) cultivated under different irrigation treatments (100% ETc, 90% ETc, 80% ETc and 70% ETc) were harvested and analyzed for moisture, ash, protein, fat, fbre, carbohydrate, calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), iron (Fe), copper (Cu) and zinc (Zn) contents. Moisture, ash, protein, fat, fbre, and carbohydrate were determined by standard AOAC methods, calcium and magnesium by EDTA titration, potassium and sodium by fame photometry, iron, copper and zinc by atomic absorption spectrophotometry. Results indicated that fat, fbre and carbohydrate increased with defcit irrigation (water stress) whilst moisture, ash, protein, calcium, magnesium, potassium, sodium, iron, copper and zinc contents decreased. Apart from fbre content which increased signifcantly during storage for all water treatments, all the other nutritional components (moisture, ash, protein, fat and carbohydrate) decreased signifcantly. Considering the percentage increases and decreases obtained for nutritional compositions of the tomatoes in this study, it can be concluded that a 10- 20% reduction in the amount or volume of water applied in the cultivation of the Pectomech tomato variety would produce tomato with optimum quality that would compensate for yield losses