The Nitrogen Nutrition of the Peach Tree II. Storage And Mobilization of Nitrogen in Young Trees

Abstract

The chemical composition and distribution of storage N in young peach trees and the importance of this stored N for new growth were investigated. Young peach trees, which were grown in sand culture for 2 growing seasons, accumulated N in proportion to supply during the 1st year, and the results suggested that this stored N was utilized for new growth during the 2nd growing season irrespective of the external N supply. Tree growth in early spring was significantly correlated with the level of storage N in tree tissues, but after Nov. tree growth was markedly dependent upon the external N supply. If fertilizer N was not applied, the supply of storage N in tree tissues was exhausted by the end of Nov. Reaccumulation of storage N began in tree tissues in Dec. and was rapid if the external N supply was high. Storage N in dormant trees consisted mainly of soluble organic N and free arginine was the principal constituent of this fraction. The level of arginine in woody tissues of the dormant trees was the most sensitive indicator of the N status of the trees. Approximately 60-80% of the storage N in dormant 2-year-old trees was found in root tissues, irrespective of the N treatment.