Evaluation of the Effect of Three Methods of Drip and Deep Subsurface Irrigation with Different Amounts of Water on Vegetative and Reproductive Characteristics of Orange Trees in Kerman

To evaluate the effect of deficit irrigation and different methods of irrigation, a field factorial experiment was carried out based on randomized complete block design with three replications at the Research Station of South Kerman Agricultural and Natural Resources Research and Education Center. In this study, the effect of different levels of irrigation (100 % of evapotranspiration (ET) in total growing stages, 60-100 % ET, and 80 % ET, except in the flowering and fruit-filling stages) under three irrigation methods (deep subsurface irrigation, subsurface drip, and surface drip) were evaluated on orange trees vegetative and reproductive traits, yield, water use efficiency, and water saving. The results showed that application of deficit irrigation based on 80% water requirement increased water use efficiency and water saving, and reduced the vegetative growth compared to normal irrigation by 3.88%, 17%, and 13.87 %, respectively. With application of deficit irrigation, yield was reduced by 13.55% compared to normal irrigation, but this reduction was not statistically significant. Subsurface irrigation caused water saving, increased vegetative traits, yield and water use efficiency, compared to surface drip irrigation by 10%, 17.02%, 17.19%, and 29.62 %, respectively. Also, the results showed that application of deep subsurface deficit irrigation (80% ET) saved 889.58 m3 of water/ha. Therefore, it can be concluded that deep subsurface irrigation can prevent the decrease in the quantity and quality of the product while saving water consumption.