Effect of deficit irrigation on total yield, fruit physical characteristics and nutritional value in four drought tolerant tomato (Solanum lycopersicum L.) genotypes

Water deficit is a major factor limiting plant productivity of fruit quantity and quality, particularly in arid and semi-arid regions of the world. The total yield, fruit physical characteristics and nutritional value of four drought tolerant tomato genotypes (KSU-TOM-102, KSU-TOM-106, KSU-TOM-107 and TL–01860) were evaluated in response to deficit irrigation (DI) under field conditions. Three levels of crop evapo-transpiration (ETc; 50%, 75% and 100%) were applied at three different growth stages (vegetative, flowering and fruiting stage) to the four tomato genotypes. Tomato genotypes differed in their responses to water deficit. Among different genotypes, KSU-TOM-102 recorded the highest average total yield (89.54 t.ha-1) under irrigation treatment with 100% of ETc during all stages as well as 75% of ETc during the fruiting stage. But, in general, total yield decreased under water deficit. Significant (P≤0.05) differences in fruits quality characteristics exerted by irrigation water treatments, tomato genotypes and their interactions. Irrigation with water at 50% ETc at all growth stages significantly (P≤0.05)  increased vitamin C, titratable acidity, total soluble solids and total sugar contents for tomato ‘KSU-TOM-107’ followed by ‘KSU-TOM-102’. But, this increase in nutritional value was accompanied with decrease in total yields by nearly 40-50%.   KSU-TOM-102 irrigated with water at 75% ETc at fruiting stage or vegetative stage recorded 0% and 12% reduction of the total yield, respectively, while maintaining good nutritional value as compared with 100% of ETc during all stages. Therefore, these treatments can be recommended as irrigation management strategy for tomato ‘KSU-TOM-102’ production under field conditions.