Effect Of Soil Moisture On Fruit Quality Of Red Fuji Apple

With development of national economy and improvement of living level, the kind of fruit in the market is becoming more and more in order to satisfy the improving demand of the customers including not only fruit volume and weight but also fruit appearance and nutritional quality. In this research Red Fuji apple was used as experimental material to study the effects of three soil water content levels (50~55%, 65~70%, 80~85% )on the fruit crack and quality, so as to lower the crack rate of apple fruit and improve fruit quality. The results were as follows:1. The crack rate and index of fruit were significantly increased with the increase of soil water content. The two parameters were the lowest under 50~55% conditions, while the highest under 80~85% conditions. The fruit crack rate in different position of fruit was peduncle stalk cavity>middle>calyx concave. From 116 days to 132 days after full flowering stage, the crack rate of apple fruit under field conditions was the highest, while the fruit crack rate of apple grown in the pot was the highest between 139 days and 155 days after full flowering stage.2. The volume and weight of apple fruit were increased with the increase of soil water content. The fruit volume and weight were the lowest under 50~55% conditions, while the highest under 80~85% conditions.3. Fruit water content, hardness, soluble solid content and organic acid content were responded differently to soil water content. Under 50~55% conditions, the fruit water content and organic acid content were the lowest, while the fruit hardness and soluble solid content were the highest. Under 65~70% conditions, the fruit hardness and soluble solid content were the lowest, while the fruit water content was the highest. Under 80~85% conditions, the organic acid content of fruit was highest, and other parameters were middle.4. There were different responses in total soluble sugar, fructose, glucose and sucrose content of mature apple fruit to soil water content. The content of total soluble sugar, fructose and glucose in apple fruit were decreased with increase of soil water content, while sucrose content was increased. However, there was little influence of soil water content on the ratio of fructose, glucose and sucrose content to total soluble sugar content. Under three levels of soil water content, the ratio of fructose, glucose and sucrose content to total soluble sugar content was about 5:2:1. But the fruit development stage had great effects on the ratio of fructose, glucose and sucrose content to total soluble sugar content. With maturing of the fruit, the ratio of fructose and sucrose content to total soluble sugar content was increased gradually and the ratio of glucose content to total soluble sugar content was gradually decreased.5. The fruit of Fuji apple contained chlorogenic acid, (-)-epicatechin, (+)-catechin, rutin and coumaric acid. And the content of the five kinds of polyphenols above depended on the organs and development stages. The content of chlorogenic acid, (-)-epicatechin and (+)-catechin in green fruit were higher than those in mature fruit. The content of (-)-epicatechin, (+)-catechin, rutin andρ-coumaric acid was higher than those in the pericarp and sarcocarp of mature fruit.6. Soil water content had little influence on the total polyphenols content in mature fruit of Fuji apple, while significantly affected the content of proanthocyanidin, chlorogenic acid, (-)-epicatechin, (+)-catechin, rutin andρ-coumaric acid. With increasing of soil water content, the content of proanthocyanidin, chlorogenic acid, (-)-epicatechin and (+)-catechin in sarcocarp gradually increased. Furthermore, the content of proanthocyanidin, chlorogenic acid, (-)-epicatechin and rutin in pericarp increased to some extent with the increase of soil water content.7. The content of mineral elements in mature fruit of Red Fuji apple was potassium> calcium>magnesium>iron>copper>zinc>manganese. The changes of mineral elements content in mature fruit depended both mineral variety and soil water content. With ascending of water content in the soil, potassium content increased, while the content of calcium, iron, zinc and manganese decreased. Changes of soil water content had little influence on magnesium and copper content. In the pericarp, calcium content lowered with increasing of soil water content. The content of potassium, magnesium and manganese in pericarp grown in the field increased with the increase of soil water content, while decreased under pot conditions. Moreover, the zinc content was also influenced by development stage besides soil water content.8. The activity of SOD, POD and PPO in apple fruit were significantly affected by soil water content. In the sarcocarp, the activity of SOD was stimulated under both 50~55% and 80~85% conditions, while the activity of POD and PPO were stimulated only under 80~85% conditions. In the pericarp, the activity of SOD, POD and PPO under 80~5% conditions were higher than those under 50~55% conditions.