Foliar Fertilization Timing in ‘Farmacista Honorati’ Persimmon (Diospyros kaki L.) Trees

Abstract

Four different timing/numbers of foliar fertilizer applications were tested on nine-year-old trees of ‘Farmacisti Honoraty’ kaki (Diospyros kaki L.) grown in northern Sicily. Trees were sprayed three times from 10 July to 3 August (EARLY), three times from 15 August to 8 September (LATE), and six times throughout the entire period (FULL) with Floral K (12-N:5-P:35-K and microelements). A fourth set of non-treated trees was used as control (CTR). Foliar nutrient content, yield and trunk circumference were measured during fall 2003. Fruit quality was determined on fruit matured on the tree or under controlled conditions. Foliar analysis showed similar N, P, Ca, Mg, B, Fe, Mn, Cu, and Zn content in leaves of all treatments, whereas CTR leaves exhibited the highest K content and EARLY leaves the lowest one. EARLY and LATE trees produced more than CTR trees, whereas yield efficiency was similar in all treatments. For tree ripe fruit, soluble solid content was highest in CTR, whereas fresh weight, acidity, and pH were similar in all treatments. In controlled ripening fruit, pH was lowest in CTR and highest in EARLY, whereas fresh weight, soluble solids and acidity were similar in all treatments. FULL and LATE anticipated fruit ripening compared to CTR, as shown by the higher percentage of tree ripe fruit on the first pick date. EARLY and LATE foliar fertilization increased yields and the reduced soluble solid content observed here may be attributable to the greater crop load. Also the lower K content in leaves of fertilized trees may be due to greater sink demand.