The nitrogen nutrition of the peach tree. VI. Influence of Autumn nitrogen applications on the accumulation of nitrogen, carbohydrate, and macroelements in 1-year-old peach trees

Abstract

An experiment was carried out on young peach trees in sand culture to determine whether differential application of nitrogen in autumn would influence the accumulation of nitrogenous, carbohydrate, and macroelement reserves in woody tissues of the trees. Increasing the nitrogen supply in autumn markedly increased the accumulation of storage nitrogen in woody tissues of dormant trees but did not influence accumulation of carbohydrate or macroelement reserves, despite the observation that foliage colour and time of leaf abscission in autumn were markedly influenced by treatments. The former result, when allied with data published earlier, indicates that autumn applications of nitrogenous fertilizer in peach orchards are an effective means of increasing tree nitrogen status. With increasing nitrogen supply, the accumulation of soluble organic nitrogen in woody tissues was especially significant, and arginine nitrogen was a major constituent of this fraction. Since amide nitrogen was synthesized along with arginine nitrogen in autumn, it is concluded that rapid arginine synthesis in peach tissues in autumn is not simply related to the relative availabilities of soluble carbohydrate and soluble nitrogen as proposed earlier. It is also suggested that experimental systems in which nutrient treatments are imposed only following cessation of plant growth could prove useful for studying the role of stored nutrients in the performance of perennial plants.