THE EFFECT OF IRRIGATION FREQUENCY AND RATE UNDER TRICKLE IRRIGATION MANAGEMENT ON YIELD GREEN BEAN GROWN IN CLAY LOAM SOIL

This study was conducted over 2 years (2013 and 2014) to establish the optimal combinations between irrigation frequency and rate for trickle-irrigated green bean using water production functions and water use– yield relationships. A field experiment was conducted using a randomized complete block design with three irrigation frequencies (F1, F2 and F3, irrigation events once every 1, 2and 3 days, respectively) and three trickle irrigation rates (I1: 1.00, I2: 0.80, and I3: 0.60 of the estimated evapotranspiration, ET). Our results show that yield variables and water use efficiencies (WUEs) increased with increasing irrigation frequency and rate, with non-significant differences between F1 and F2 in yield variables and between I1 and I2 in WUEs. Moreover, the combination between various irrigation frequencies and rates had an important effect on yield variables and WUEs, with the highest values being found with F1I2 and F2 I1 and the lowest for F2I3 and F3I3. The F1I3 treatment had grain yield and yield components values similar to those obtained for the F2I3 treatments and WUEs values similar to those obtained for the F2I3 and F3I1 treatments. Production functions of yield versus seasonal crop ET were linear for all combinations of irrigation frequency and rate and for all irrigation frequency treatments with the exception of the F1 treatment, which instead showed a second order relationship. In conclusion, we identified the optimal coupling combinations between irrigation frequency and water application rate to achieve the maximum yield and WUEs.