Influence of Nitrogen on the Contents of Carbohydrates and Organic Acids in Apples (Mo/us domestica Borkh.) cv. 'Golden Delicious'

摘要

The aim of the experiment was to ascertain the dependence of the carbohydrates (sorbitol, sucrose, glucose and fructose) in fruits and leaves, organic acids in fruits, nitrogen content in leaves and leaf chlorophyll content according to the differentrates of nitrogen supply. The analyses were conducted on 13-year-old cv. 'Golden Delicious' apple trees (Malm domestica Borkh.), which were either fertilized with 80 kg N ha (N-80) or 200 kg N ha~(-1) (N-200) or not fertilized (N-0) as control. The leafnitrogen content was significantly higher in the treatment N-200 than in the N-0 treatment. A seasonal decrease in leaf nitrogen content was noticed in all treatments. Leaf SPAD (indexed chlorophyll content) readings were increasing until the end of July and then stagnated. All over the season, the readings were significantly higher in treatment N-200 than in the N-0 treatment and from mid- June to end of July also higher than in the N-80 treatment. The nitrogen supply did not affect the content of single sugars nor did it affect total sugars in the leaves. The nitrogen fertilization had no effects the level of sorbitol in the fruits; increased N-supply resulted in lower contents of sucrose and fructose and higher contents of glucose in fruits. As fororganic acids, the nitrogen supply caused higher concentrations of citric acid.