Effects on Early Growth in the Next Year of Urea Foliar Application after Harvest and Distribution of Nitrogen Derived from Foliar Spray on ‘Shimizu-hakuto’ Peach Tree

Abstract

We have investigated the effect of foliar urea sprays applied at the end of August and early September to promote early growth of ‘Shimizu-hakuto’ peach. The leaf color value measured by SPAD increased on urea application compared with the control. The size of the ovary was larger and the leaf color value was higher the next year. However, there was no significant difference in the fruit set. In order to confirm the distribution and utilization of nitrogen components derived from foliar spraying, ¹⁵N-labeled urea was sprayed twice on a 6-year-old pot-planted tree from late August to early September. We noted the rapid transportation of ¹⁵N to each part of the tree. A total of 28.9% of the nitrogen attached to the tree was absorbed. The absorbed nitrogen was translocated to other parts such as branches and roots, and distribution rates in flower buds, current shoots, and one-year-old wood in December were higher than in other parts. In the next year, the utilization rate in new tissues such as leaves and young fruit was about 3%, respectively.