Vegetative growth and water use efficiency of citrus seedlings in simultaneous application of shading and partial root zone drying

Due to climate change and increasing of water demand for agricultural productions, optimum use of water resources is necessary. In this experiment, the effects of partial root zone drying (PRD) along with shading were investigated on growth and water use efficiency of 2-year old sour orange seedlings in Ramsar, northern town near Caspian Sea, Iran. The pot experiment were assigned to a completely randomized design and were treated during seven months in 2015. Treatments were full irrigation (FI), partial root zone drying (PRD), PRD along with moderate shade (MShPRD) and PRD along with high shade (HShPRD). Irrigations water volumes were determined on the basis of soil moisture deficiency. Water consumption reduction relative to FI treatment for PRD, MShPRD and HShPRD treatments were 29.6, 36.2 and 39.2 percent, respectively. Mean comparion indicated that trunk diameter, dry weight ratio of root/total plant and root variables (dry and fresh weight, volume, length, area and length density) in HShPRD were significantly lower than those of other treatments. Also, total dry matter and volume and weight of stem and branches in HShPRD were lower than those of full irrigation treatment. Dry weight ratios of leaf/total plant, shoot/total plant and shoot/root in this treatment were higher than those of other treatments. Treatments had no significant effect on leaf variables, plant height, branches length, root diameter and specific root area and length. In conclusion, the highest irrigation water use efficiency was observed in MShPRD, but it had significant difference only with full irrigation.