IMPACT OF POSTHARVEST SPRAYS OF NITROGEN, BORON AND ZINC ON NUTRITION, REPRODUCTIVE RESPONSE AND FRUIT QUALITY OF 'SCHATTENMORELLE' TART CHERRIES

The aim of the study was to examine effects of fall sprays of nitrogen (N), boron (B) and zinc (Zn) on nutrition, reproductive response, and fruit quality of tart cherry (Prunus cerasus L.). The experiment was conducted during 2008-2010 in Poland on mature Schattenmorelle' sour cherry trees, planted at a spacing of 4.0 x 1.5m on a coarse-textured soil with low level of organic matter, and adequate reaction and availabilities of macro- and micronutrients. Tart cherries were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 40-50 d prior to initiation of leaf fall according to following schema: (i) spray of N at a rate of 23kg ha(-1); (ii) spray of B and Zn at doses of 1.1kg ha(-1) and 0.5kg ha(-1), respectively; and (iii) spray of N, B, and Zn at the same rates as in the above spray combinations. The trees sprayed with water were served as the control. The results showed that postharvest spray treatments had no effect on defoliation, cold damage of flower buds, fruit set, yielding, plant N status, mean fruit weight, and soluble solids concentration in fruit. Postharvest sprays of B and Zn with or without N enhanced status of Zn and B in fall leaves, and B in flowers but had no impact on levels of the above micronutrients in summer leaves. Leaf-absorbed B was withdrawn in the fall, whereas Zn was immobile. It is concluded that postharvest B sprays can be recommended to increase B status in flowers of tart cherry, whereas fall sprays of urea-N and Zn are not able to improve plant nutrition of those nutrients the following season.