Study Of Potassic Fertilizer Application Technology And The Relationship To Fruit Growth And Quality Formation In ’Kousui’ Pear

The sand pear cultivar ’Kousui’(Pyrus serotina Kousui)was used as experimental materials in this article.The effects of different fertilizing stages,fertilizing methods and potash fertilizer kinds on the quality of pear fruit were compared,the relationship between the contents of potassium in leaves and fruit and the components of sugar and acid in fruit were analyzed,the correlation between changes of fruit potassium content and fruit fresh weight was discussed,the effects of GA3 and GA4+7 on the growth and quality of pear fruit were studied.The main result showed that as follow:1.The content of potassium in fruits was significantly higher than that of leaves,the potassium content largest gap was more than 3 times between mature fruits and leaves.The potassium content in mature fruit was significantly correlated with fruit weight,but there was no correlation between the changes of leaf potassium content and fruit weight;2.The sugar components of ’Kousui’ fruit were mainly composed of sucrose,glucose,fructose and sorbitol,in which the contents of fructose and sorbitol were the main sugar components;the acid components of the fruit were mainly composed of oxalic acid,quinic acid,malic acid,shikimic acid and citric acid,in which malic acid and quinic acid were the main organic acids;3.Before the rapid expansion of fruit,the potassium content in leaves was synchronized with the accumulation of fructose and glucose in the fruit cells,and during the period of leaf growth,the change of potassium content in leaves was synchronized with the change of sorbitol content in fruit.Following the increase of potassium content in fruits,the content of soluble sugar advanced,and the content of total acid decreased obviously in fruits as well;4.Applying potassium at different time could make potassium contents raise significantly in leaves and fruits,but applying potassium at early July made potassium content in fruits the highest.The effect of fertilization on potassium content in leaves commonly showed 2-3 weeks after applying potassium;5.The foliage spray potassium increased potassium content in young leaves,and the foliage spray with KNO3 raised significantly the fruit firmness.The foliage spray with KH2PO4 enlarged the leaf area in middle of shoots,increased contents of soluble solids and fructose,decreased content of malic acid in fruits;6.Treatment of 1.5%GA4+7 significantly improved potassium content,increased fruit fresh weight,promoted the accumulation of sucrose,reduced the content of citric acid and sorbitol,raised the contents of soluble solids and soluble sugar in fruits.In the same time,the length and thickness of the carpopodium increased and the firmness of the fruit decreased as well by the treatment.