Salinity and Deficit Irrigation Influence Tomato Growth, Yield and Water Use Efficiency at Different Developmental Stages

Deficit irrigation (DI) is an optimization strategy that allows water stress to some extent during certain cropping stages or for the whole season without a significant reduction in yield. A greenhouse experiment was conducted during the growing seasons of 2009/2010 and 2010/2011 to study the effect of water quality and DI on growth, yield and water use efficiency (WUE) of tomato at different growth stages. Two different water qualities (saline and non-saline water with electrical conductivities (EC) 3.6 and 0.9 dSm(-1), respectively) nine DI treatments and three irrigation treatments (100, 75 and 50% of Etc) were investigated in the experiment. Furthermore, DI at 75% and 50% of ETc during vegetative, reproductive, and fruiting stage were adopted. The result indicated that in general the irrigation with saline water decreased tomato fruits yield and WUE. Moreover, the negative effect of DI was more obvious when coupled with salt stress. Irrigation with saline water resulted in 22% and 24% reduction in yield during first and second season, respectively. Fruiting and vegetative growth stages were the most tolerant to DI; whereas, the reproductive stage was the most sensitive one. The crop response factor (Ky) values ranged between 0.24 and 0.75. Irrigation with non-saline water at 75% ETc at fruiting or vegetative growth stage did not significantly decrease the growth and fruit yield but enhanced WUE, increased vitamin C and total soluble solids (TSS) content and saved 10% of irrigation water. Therefore, this treatment can be recommended as an irrigation management strategy for tomato production under greenhouse conditions. By using this strategy, approximately 21% of irrigation water can be conserved without reduction in yield. (C) 2015 Friends Science Publishers