In a study carried out during 1996 and 1997 in Kalubia Governorate, Egypt, 27-year-old Washington navel orange trees budded on sour orange rootstock, showing Fe, Zn and Mn deficiency symptoms, received foliar nutrition of 400 ppm of NaFe EDTA, Na2Zn EDTA and Mn EDTA 3 times a year (at the beginning of flowering, after fruit set, and 4 weeks later) either solely or at different combinations. Untreated trees with or without deficiency symptoms were used as the control. Application of Fe+Zn+Mn chelates improved the nutritional status of deficient trees. This treatment improved growth parameters (shoot percentage and shoot length of different growth flushes) and leaf chlorophyll content. Total yield as well as fruit weight and number were increased with this treatment. Fruit juice content, total soluble solids (TSS), TSS/acid ratio and ascorbic acid content were also increased, while acidity was decreased compared to the control with deficiency symptoms. The Fe+Zn+Mn spray treatment was comparable to the healthy control regarding most of the parameters. |
