Effect of Time and Amount of Supplemental Irrigation at Different Distances from Tree Trunks on Quantity and Quality of Rain-fed Fig Production

Abstract

Supplemental irrigation under prolonged drought conditions has a key role in providing water for transpiration of rain-fed fig trees. The effect of different times and amounts of supplemental irrigation at different distances from the tree trunk on quantity and quality of Estahban rain-fed fig production was evaluated during two years. A randomized complete block design with four replications on fig cultivars of Sabz was used to conduct the experiment. Treatments of supplemental irrigation included three different application positions including: close to tree trunks (NT); 1-1.1 m from tree trunk (UT) and outside of tree canopy (OT), using three different quantities of irrigation water as no supplemental irrigation (control), 1000 and 2000 liters irrigation water per tree, and with two different supplemental irrigation times in early spring and mid-summer. Results showed higher soil water content for irrigation during early spring, near tree trunk with 2000 liters irrigation water per tree. Despite the reduction in total soluble solids (TSS), supplemental irrigation improved the yield, size and skin color of fruits compared to the control. In both years, fig yield was higher in NT and OT treatments compared to UT. Irrigation out of canopy produced more fruits with higher quality. A non-significant difference between yields in irrigation water amount treatments during the second year indicated the adequacy of 1000 liters per tree. Application of 1000 liters, out of canopy in mid-summer would be recommended to fulfill marketing goals and sustainable use of regional water resource under drought conditions in rain-fed fig orchards.