Effects of Both Regulated Deficit Irrigation and Super Absorbent on the Vegetative Growth, Yield and Fruit Quality of Japanese Plum  Santarosa'

Using of Regulated Deficit Irrigation (RDI) and improved water holding of soil are very important in irrigation of fruit trees. For this purpose, the effects of both RDI and super-absorbent (SA) were studied on the vegetative growth, yield and amount of marketable fruit and some quality characteristics of Japanese plum (Prunus salicina cv. ‘Santarosa’). The trees were exposed to three RDI levels including 100% ETc, 75% ETc, 50% ETc and four super-absorbent levels of zero, 100, 200, and 300 grams/tree at the pit hardening stage. In RDI, the difference of vegetative growth compared to control trees was significant and the SA treatments could not compensate for the decrease of vegetative growth. The amount of yield was not affected under the influence of 75% ETc, but at the 50% ETc level, it decreased significantly. The yield of control, 75% ETc and 50% ETc treatments were 47, 46.15 and 35.50 kg/tree respectively. However, comparing between control and other levels of RDI showed that the amount of marketable fruit increased in 75% Etc. In addition, the irrigation levels were not effective on soluble solid content (SSC), titrable acidity (TA), SSC/TA and the magnesium (Mg) concentration. While, the concentration of fruit calcium increased considerably under RDI and the highest amount of Ca was observed at 50% Etc. The quality characteristics such as total phenol, firmness and antioxidant potential of fruits increased by lower irrigation than the control fruits. In this study, the interaction effects of RDI and SA treatments were significant only for total phenol trait.