Selection Of Suitable Rootstock And Study On Potassium Nutrition Characteristics In Sweet Persimmon

In this paper,the effects of different stocks and potassium application rates on nutrient elements absorptions and qualities of tested varieties were compared using the sweet persimmon cultivar ’Taishuu’ as test materials.The characteristics of potassium storage and distribution in the organs during period of dormancy and germination were studied.The relationships between the change of potassium contents in leaves and fruits and the metabolism of sugar and acid in fruits was analyzed.The main findings show that:The contents of phosphorus,potassium,calcium,iron,manganese and zinc in the leaves of ’Taishuu’ grafted on the Dabieshan were significantly higher than those of Taishuu’ grafted on the ’Nantongxiaofangshi’ and ’Zenjimaru’.The contents of nitrogen and calcium in the fruits of ’Taishuu’ grafted on the Dabieshan and Yizhengyeshi were significantly higher than those of Taishuu’ grafted on the’Nantongxiaofangshi’ and ’Zenjimaru’,while the contents of zinc is significantly lower than those of Taishuu’ grafted on the ’Nantongxiaofangshi’ and ’Zenjimaru’.The average fruit weight of the Taishuu’ grafted on the Dabieshan and Yizhengyeshi were significantly higher than those of Taishuu’ grafted on the ’Nantongxiaofangshi’and ’Zenjimaru’,while the contents of soluble tannin in the fruits of ’Taishuu’ grafted on the ’Nantongxiaofangshi’ and ’Zenjimaru’ were significantly higher than those of’Taishuu’ grafted on the Dabieshan and Yizhengyeshi.The contents of glucose,fructose and maltose in the fruits of the ’Taishuu’ grafted on ’Nantongxiaofangshi’Dabieshan and Yizhengyeshi were no significant differences,while the contents of malic acid,citric acid and total acid in the fruits of the ’Taishuu’ grafted on’Nantongxiaofangshi’ were significantly higher than fruits of the Taishuu’ grafted on the other three rootstocks.According to the analysis results of the changes of nutrient elements and fruit quality formation indexes of ’Taishuu’ grafted on the four tested rootstocks,Dabieshanyes and Yizhengyeshi can be used as an alternative rootstock for the cultivation of Taishuu’ sweet persimmon in the central region of Jiangsu Province.The contents of Nitrogen,phosphorus,potassium,calcium,magnesium,iron,copper,manganese and zinc in sweet persimmon fruits were higher than leaves.The contents of manganese and zinc in leaves were significantly different from those in fruits,and the contents of manganese,calcium and phosphorus in leaves were 14 times,10 times and 1.25 times as much as those in fruits,respectively.The absorption of potassium with magnesium,calcium and manganese in leaves and fruits of persimmon showed positive interaction.The absorption of potassium,iron and zinc in leaves and fruits of persimmon showed negative interaction.The absorption of potassium and nitrogen,phosphorus and copper in leaves and fruits of persimmon were independent.The results showed that the absorption of nine elements in leaves and fruits of persimmon was synchronous.The changes of potassium contents in leaves had a significant effect on fruit weight growth,while the changes of potassium contents in fruits considerably affected the contents of sugar and acid composition in sweet persimmon.There was a significantly linear correlation between the growth of fruits and changes of potassium content in leaves,and potassium in leaves was one source of potassium required for fruit enlargement.During the fruit ripening period,the potassium content range of 6.4～9.6mg/g DW in leaves could promote the increasing of single fruit weight Biosynthesis of glucose and fructose could be boosted if the potassium contents was in range of 4.6-4.8mg/g DW,but accumulation of organic acids was inhibited when the scope of potassium content was 4.4-4.6mg/g DW in fruits.Taking account of the effects of changes of potassium contents in leaves and fruits on single fruit weight and sugar acid constituents.Taking account of the effects of changes of potassium contents in leaves and fruits on single fruit weight and sugar acid constituents.It is considered that the appropriate range of potassium contents in leaves and fruits was 6.4-9.6 mg/g and 4.6-4.8mg/g respectively during the fruit ripening periodThe bioaccumulation of the fruit was the highest in the organs of trees accounting for 39.39%,and 45.23%of the annual bioaccumulation was taken away from the tree by fruits and leaves.In the dormant period,the proportion of potassium accumulation in each organ was as follows:trunks>one-year branches>two-year branches>three-year and above branches>taproots>lateral roots>fibrous roots,in which the accumulation of potassium of trunks was the highest(22.97%).During the germination stage,the potassium required for the growth of new roots in the underground was mainly derived from the main roots of the underground storage organs.The potassium required for the young leaves and germination of the shoots was mainly derived from the above-ground storage organs such as the three-year-old and above branches.The author believed that the nearby distribution was one of the main forms of potassium storage in persimmon trees.