Effects of Nitrogen Absorbed during Summer and Autumn on Shoot Growth, Fruit Quality and Yield in ‘Muscat of Alexandria’ Grape under Forced Culture from December

Abstract

This experiment was intended to examine the effects of nitrogen absorbed during summer and autumn on shoot growth, fruit quality and yield of forced cultured 'Muscat of Alexandria' grape. After harvest in May, three groups of trees (each group consisted of three trees) were applied for fertilizer experiment. Nitrogen was fertilized for each group by three different levels of 5 g, 10 g and 15 g N・m −2 in summer and the same amount of nitrogen (12 g N・m −2 ) was applied for all groups in autumn.Warming started on December 14. Before blooming, there were no differences in shoot elongation between plants treated with 10 g and 15 g. However, significantly less growth was observed in those treated with 5 g. After blooming, the difference in shoot elongation became less than that before blooming and there was almost no difference in cluster weight or berry size and yield among treatments. However, pH and Brix in juice were obviously less in plants treated with 5 g. Correlation analysis of the leaf area, flower cluster numbers per shoot, fruit quality and yield was performed with respect to nitrogen absorbed in summer and autumn. Consequently, the appropriate amount of nitrogen absorbed in summer or autumn is supposed to be 8 g・ m −2 per plant.