Effects of Zinc Sulfate and Potassium Nitrate on Growth, Fruit Yield and Oil Percentage of Olive cv.  Amygdalifolia'

This research was carried out to investigate the effects of foliar application of zinc sulfate (ZnSO4) and potassium nitrate (KNO3) on qualitative and quantitative characteristics of fruit, and oil yield of 11-year old olive trees cv. ‘Amygdalifolia’ at the Kazerun Olive Research Station during 2007-2008 years. A factorial experiment 4×4 was arranged in a randomized complete block design with four replications. Treatments were four levels of zinc sulfate (0, 0.25, 0.50 and 0.75%) and four levels of potassium nitrate (0, 0.5, 1.0 and 1.5 %) applied alone and in combination at the beginning of second and third stages of fruit growth. On the bases of fruit growth curve, 45 and 120 days after full bloom respectively, were the beginning of metioned stages. The results indicated that high fruit volumes were obtained in 0.5% zinc sulfate and 0.5% potassium nitrate combination. Fruit weight was influenced by using of zinc sulfate and potassium nitrate and improved in comparison with fruits of control trees. So, the highest fruit weight was achieved in combination of 0.5% ZnSO4 and 0.5% KNO3. Zinc sulfate and potassium nitrate had significantly effect on fruit oil. Maximum oil percentage in dry and wet fruit weight were achieved by using 0.5% ZnSO4 + 1% KNO3 and 0.5% ZnSO4, respectively. Application of both zinc sulfate and potassium nitrate had some interaction effects on fruit phenol content and the highest phenol content of fruits was observed by using of 0.5% ZnSO4 + 1.5% KNO3. Therefore, for increasing fruit yield application of 0.5% zinc sulfate + 0.5 potassium nitrate can be suggested during second and third stages of fruit growth.