Effects of irrigation scheduling on drip-irrigated processing tomatoes

A series of trials were conducted over a period of three growing seasons in the northern coastal plain of Israel in order to determine optimum timing of beginning and end of drip irrigation (irrigation-start and irrigation-end times) of processing tomatoes (Lycopersicum esculentum Mill.). The examined cultivars, characterized by intensive and vigorous vegetative growth (cv. Brigade and cv. AB 3049), were planted on a clay texture soil. Yield, fruit quality and soil-water tension were measured. In the first trial, three irrigation-end times (0%, 30% and 80% fruit ripening) were tested. With cv. AB3049 fresh yields increased significantly as irrigation-end time was delayed and soluble solids content was significantly reduced as a function of irrigation-end time. With cv. Brigade, whereas fresh yield increased significantly as irrigation-end time was delayed with 0% and 30% fruit ripening, soluble solids content decreased significantly at each stage that irrigation was delayed. The second and third trials included a combination of two irrigation-start times (fruit set in the second and third florescence and in the fourth and fifth florescence) and two or three irrigation-end times (30% and 80% fruit ripening or 15%, 50% and 80% ripening in the second and third trials respectively). Delayed beginning of irrigation resulted in significant decrease in fresh yield due to a decrease in the number of fruits, and no differences in soluble solids content with both cultivars. Delaying end of irrigation had different effects with the two cultivars. With cv. Brigade, there were no differences in red fruit yields as irrigation ended at 15% to 80% fruit ripening whereas a significant decrease was measured in soluble solids content when irrigation was delayed up to 80% fruit ripening. With cv. AB3049 there were no differences in red fruit yields as irrigation ended at 50-80% fruit ripening whereas a significant decrease occurred in soluble solids content when irrigation was delayed up to and above 50% fruit ripening.