12月加温作型のブドウ'マスカット・オブ・アレキサンドリア'における夏季および秋季の窒素吸収量と新梢成長,果実品質および収量との関係(栽培管理・作型)  [in Japanese] 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(Crop Production & Cropping Type)  [in Japanese]

養液栽培したブドウ'マスカット・オブ・アレキサンドリア'樹を用いて,12月加温作型における夏季および秋季の窒素吸収量が翌年次の新梢生育,果実品質および収量に及ぼす影響を検討した,果実を5月に収穫した後,夏季(6〜7月)に3水準(窒素成分量で15g,10gおよび5g・m^<-2>)の施肥を行い,秋季(9〜10月)には同量(12g・m^<-2>)の窒素を施肥して12月14日から加温を行った.開花期までの新梢の成長は,夏季施肥窒素量15g・m^<-2>および10g・m^<-2>の両処理間では大差なかったが,5g・m^<-2>施肥区では明らかに遅れた.開花期以後の新梢成長,成熟果実の果房重,果粒重および収量における区間差は小さくなった.しかし,糖度およびpHは5g区で明らかに劣った.新梢当たり花穂数,葉面積,果実品質,収量と夏季,秋季の窒素吸収量との関係を回帰分析で検討した.その結果,夏季および秋季の適正な窒素吸収量はともに8g・m^<-2>程度と考えられた.

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 5g, 10g and 15gN・m^<-2> in summer and the same amount of nitrogen (12gN・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 10g and 15g. However, significantly less growth was observed in those treated with 5g. 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 5g. 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 8g・m^<-2> per plant.