The effect of time and different concentrations of foliar spraying fertilizers on fruit physicochemical properties and yield of jujube (Ziziphus jujube)

Jujube (Ziziphus jujube) is cultivated widly in Southern Khorasan province. The tree is adapted to arid and warm regions. In this study, urea at 5 concentrations (0%, 1%, 2%, 3% and 4%), boric acid, iron sulfate and zinc sulfate, each with five concentrations (0, 1500,2500,3500 and 4500 mg/lit) alone and in combination with each other were sprayed at three different times before flowering, before flowering 30 days after petal abscission and 30 days after petal abscission on jujube. This experiment performed as factorial in the form of randomized complete blocks design with three replications. The results showed that the spray before flowering and before flowering 30 days after petal abscission caused significant increase in fruit size (length and diameter), fruit weight, yield and TSS (Total Soluble Solids) than spraying in 30 days after petals abscission. Urea, boric acid and Urea boric acid iron sulfate zinc sulfate significantly increased fruit size (length and diameter), fruit weight, yield and TSS in comparison with Iron sulfate and zinc sulfate. All concentrations compared to control significantly increased fruit size (length and diameter), fruit weight, yield and TSS. Foliar spraying fertilizers had not significant effect on the other chemical properties of fruit (Vitamin C, pH, Acidity and amount of carotenoids).