Regulated deficit irrigation (RDI) is commonly used during different phenological stages of fruit growth and development in almond trees to reduce the amount of irrigation water applied without or with only very small reductions in yield. Therefore, to study the effects of deficit and cutoff irrigation during different phenological stages of fruit growth and development in almond cv. “Mamaei” production, an experiment was carried out in a split plot on randomized block design with three replications. The main plots were three different phenological stages of fruit growth and development i.e. Stage I (fruit growth period), Stage II (kernel growth period) and stage III (preharvest period). The subplots had different irrigation regimes, namely T1= 100% ETc (Full irrigation), T2= 80% ETc (deficit irrigation), T3= 40% ETc (deficit irrigation) and T4= 0% ETc (cutoff or drought period). Traits such as fruit size (length, width and diameter), fresh and dry weight of fruit, fresh and dry weight of kernel, percentage of fruit drop, kernel percentage and yield were measured. The results showed that deficit and cutoff irrigation during stage-I decreased fruit size, both fresh and dry weight of fruit. Deficit and cutoff irrigation during stage-II decreased fruit fresh weight, fresh and dry weights of kernel, but no significant differences were observed for the measured traits when irrigation treatments were applied at stage III. These results indicated that preharvest stage (stage III) in ‘Mamaei’ cultivar has low sensitivity to deficit irrigation. Therefore, it is concluded that deficit irrigation with 40% of full irrigation (%40 ETc) during stage III for two months prior to harvest can be used without considerable reduction of yield for this cultivar under the climatic conditions in Saman region.
