Evaluation of the Effect of Supplemental Irrigation with Saline Water on Quality and Quantity of Rainfed Fig Fruit

The largest area of rainfed fig orchards in the world, with more than 22000 hectares, is located in Estahban, Fars province. During the last two decades due to frequent droughts and lack of fresh water resources in this area, the saline groundwater has been applied for irrigating fig trees. In the past, no comprehensive research has been done on the effects of supplemental irrigation with saline water on rainfed fig orchards. This study investigated the effects of saline irrigation water (7.38-7.8 dS/m) and high soil electrical conductivity on the quality and quantity of rainfed fig during 2010-2011. Experiments were carried out in a private rainfed fig orchard located in the village of Khane-Ket by sampling soil and roots in different parts of the garden. The results showed high tolerance of fig trees to high EC values of water and soil. However, increasing soil salinity under uniform irrigation conditions reduced the yield. Based on the results, there is a negative linear correlation between salinity and yield, with the coefficient of determination (R2) equal to 0.5. A 36 percent reduction in EC values could increase the yield by 68 percent. Also, the regression equation between EC at different depths and the amount of production was obtained. Also, by determining the EC profile in the soil, its maximum value was found at a depth of 60-90 cm. In terms of fruit quality, soil salinity did not significantly affect fruit color and size; however, it increased the total soluble solids (TSS) of fruits.