YIELD RESPONSE OF TOMATOES TO SOIL-MOISTURE REGIMES

The effect of two irrigation frequencies (daily and every 3 days) and three water application rates (3,6 and 9 mm day(-1)) on the growth and yield of tomatoes were investigated under the relatively warm and hum id winter conditions of Oman in the Gulf region. The three water appli cation rates were 0.6, 1.2 and 1.8 times the reference evapotranspirat ion as computed by the Penman modified method, and corresponding to ma ximum soil moisture tensions of more than 100 K Pa, less than 80 K Pa and field capacity, respectively. Daily - and every 3-day irrigations did not produce any statistically detected effects on fruit weights, n umbers, dry matter content and total yield or on root volume of tomato es. Significant differences were obtained in total yield and fruit wei ghts when the application rates were increased from 3 mm day(-1) (0.6 ET(0)) to 6 mm day (1.2 ET(0)) with no significant increase in yield o r fruit weight when further increasing the application rate to 9 mm da y (1.8 ET(0)). Maintaining less than 80 K Pa soil moisture tensions op timized yield and fruit numbers, whereas maintaining field capacity le vels maximized fresh fruit weights. Fruit setting, percent dry matter and root weight and volume of tomatoes were not affected by any of the soil moisture regimes adopted.