Effect of postharvest soil and foliar application of boron fertilizer on the partitioning of boron in apple trees.

摘要

This study was carried out on mature 'Delicious' apple trees (Malus domestica Borkh.) on EM 9 rootstock. Labelled B (99.63 Atom % 10B) was applied as boric acid. Treatments were postharvest foliar B at 375 mg.L-1, postharvest foliar B (375 mg.L-1) plus urea (2.5% wt/vol), and a soil application at the same per-tree rate as the foliar treatments (16 g boric acid/tree). Postharvest foliar B applied with or without urea was efficiently transported from the leaves into storage tissues for the next year's growth. However, soil-applied B remained mostly in the roots while very little was translocated to the above-ground portions of the tree at full bloom. When urea was added to a foliar B spray, the amount of B in the roots and flower clusters increased at full bloom. Although increasing the efficiency of foliar B applications may not be necessary, combining urea and B into a single application is recommended when growers want to apply both N and B. Shoot leaves from all treatments collected late in the season (midsummer) had similar B concentrations, even though treatments altered the amount of added B that was present in different tree tissues early in the season..