Effect of different amounts of irrigation water on the yield of Yaghuti grape

Yaghuti grape is an important grape variety mostly found in subtropical regions of Iran. Studies have shown that many of Yaghuti grape orchards are over irrigated which in addition to having a negative impact on groundwater resources; also reduce the quantity and/or the quality of the fruit. Up to now, little work has been done to determine water requirement of this variety. To do so, a study was conducted in a Yaghuti grape orchard in Qir-karzin region in Fars Province, Iran for a period of 2 years. Different amounts of irrigation water based on 60, 80, 100 and 120 percent of crop water requirement estimated by the Penman-Montieth method were applied to the experimental treatments in four replications. An irrigation treatment managed by the farmer was also considered as control. Results showed that different amounts of irrigation water given to Yaghuti grape did not affect the quality or quantity of the fruit. Comparison of soil moisture and canopy temperature measured before irrigations with the corresponding critical limits also indicated that none of the treatments had faced water stress .However, the treatment irrigated with 60 percent of crop water requirement was approximately the starting point of water stress. Therefore, it is concluded that the best irrigation amount could be based on 60 percent of crop water requirement estimated by the Penman-Montieth method equivalent to irrigation volume of 3800 cubic meter per hectare.