Effect of Zinc and Boron on Vegetative Growth, and Fruiting of Manzanillo Olive Tree under Siwa Oasis Conditions

Abstract

This study was carried out during 2018 and 2019 seasons on Manzanillo cv. olive trees (Olea europaea L.) located at Siwa Oasis, trees were planted at 5x5 meters apart in sandy soil, under surface irrigation system. The trial was conducted as split plot design with three replication, zinc sulphate in main plots (2 g/l, 4 g/l and 6g/l) and boric acid (1.5 g/l, 3 g/l and 4.5 g/l) located in the subplots, foliar sprays of zinc sulphate and boric acid treatments at two times i.e., the first was done before flowering on end of February and the second one was 1 st May to compare an effects on vegetative growth, flowering, and fruiting on olive trees. The results showed that vegetative growth i.e tree height, both the circumference and diameter, shoot growth, leaf characteristics (length, width and area of leaf blade), flowering characteristics (Panicles number per shoot, number of flower per panicle and perfect flower percentage), fruit setting (initial fruit set percentage and the initial number of fruitlets), recorded the highest values with higher both zinc sulphate and boric acid treatments. Subsequent fruit retention (%) from the first of June until to the first of October were recorded the highest values with zinc sulphate 6 g/L or 4 g/L, plus boric acid 4.5g/L or 3 g/L, the lowest values were recorded with zinc sulphate 2 g/L plus boric acid 1.5 g/L.