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.
This study investigated the real-time diagnosis of potassium concentration in 'Muscat of Alexandria' grapes grown in a soilless culture system using perlite medium. Potassium concentration in the squeezed sap of the petiole was investigated at different growth stages. Its relations to the severity of leaf injury attributable to potassium deficiency at stage III of fruit growth and fruit quality were assessed. Potassium concentration lower than 500 mg・L −1 in sap at veraison engenders a higher correlation between the potassium level and leaf scald severity. These signs are more severe in plants with lower potassium concentrations. There were no such signs when potassium concentrations in the sap greater than 500 mg・L −1 . At 1000 mg・ L −1 or lower potassium concentration in the sap at veraison, a positive relationship was also observed between the potassium level and berry size. Berry size was smaller when the potassium level in the sap was less than 1000 mg・L −1 . Even when the potassium concentration was 4000 mg・L −1 , an extremely low sugar content, implying a lower commercial value, was not observed. Relationships between potassium concentrations in the sap at the berry set stage and leaf scald or fruit quality were not clearer than those at the veraison stage.
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