effect of regulated deficit irrigation and partial root zone drying on quality and quantity performance of orange

awareness of the effects of water deficit on quality and quantity yield of orange is essential for product managing at water shortage conditions. in this regard, present study was conducted in an orange garden of babol area in 2011 in a completely randomized design with 5 treatments and 5 replications. experiment treatments included full irrigation (fi), regulated deficit irrigation (rdi) and partial root zone drying (prd) in two levels 75% and 55% of fi treatments. the root zone moisture was measured by tdr sensors. the amount of irrigation water was determined from difference between initial soil moisture before irrigation and moisture at field capacity point.measured qualitative and quantitative characteristics of fruits were included fruit fresh and dry weight, fruit moisture, fruit volume, dimensions, total dissolved solids (tds) and treatable acidity (ta). irrigation water depth at fi was 169.44 mm and water saving in deficit irrigation treatments at 75% and 55% levels were 17.44% and 31.39%, respectively. comparison of means was conducted by duncan test at 5% level. the results showed that differences between fi and prd in attributes of fresh and dry weight, moisture and volume of fruit were not significant. di and prd compared with fi showed a significant increase in tds and ta at harvest. the results showed that, di and prd compared with fi were caused significant increase in fruit quality. it is recommended to use prd and di at 75% level to save water and increase the product quality.