| The effects of different rootstocks on growth, development and fruit quality formation of grafted watermelon in soilless medium culture have been studied in this paper. The mainly planted watermelon variety Zaojia (CK) in Shanghai and two grafting methods have been used in the experiments. Five grafting treatments were selected as Zaojia/Jiangjun, Zaojia/Huazhen-2, Zaojia/ChaofengF1, Zaojia/Kangzhen-2 and Zaojia/Xiyu compared with the Zaojia(CK). The results were as follows:1. Effect of rootstocks on growth and development of grafted watermelon1.1 Different grafting treatments had different grafting compatibility. The survival rate of grafting watermelon had no significant difference in two grafting methods, but was significantly influenced by genotypes of rootstocks. Zaojia/ChaofengFl and Zaojia/Huazhen-2 had better grafting compatibility, and their survival rates were also higher than that of others. All grafting treatments grew better than Zaojia.1.2 Different rootstock species had significant effects on photosynthesis of grafted watermelon plants. Chlorophyll contents of the grafted watermelon leaves among different rootstocks had no significant difference. Chlorophyll contents and photosynthesis of grafted watermelon are higher than Zaojia.1.3 Effect of rootstocks on nutrient absorbability of grafted watermelon had been tested in this program. The total root absorbing area and active absorbing area of grafted watermelon roots were higher than that of Zaojia, and it was also significant difference among different treatments. The root volume and root vigure of Zaojia/Kangzhen-2 were obviously superior than that of other treatments and Zaojia. Grafted with different rootstocks, the seedlings absorption were also different. Zaojia/Kangzhen-2 had more absorption of K+, 1020.90ppm ;Zaojia/Xiyu had more absorption of Na+,48.13ppm; while Zaojia/Jiangjun and Zaojia/ChaofengF1 had more absorption of phosphorus. The bleeding sap quantities of grafted treatments were obviously higher than that of Zaojia.1.4 Watermelon yields were obviously enhanced by grafting. Zaojia/Kangzhen-2 produced the highest yield. Watermelon yields of all grafting treatments were higher than Zaojia except for Zaojia/Huazhen-2. And this consisted with the growth and root absorbency of grafting treatments.2. Effect of rootstocks on fruit development and quality formation of grafted watermelon2.1 Sugar contents of different treatments had the same changes during fruit development. Sucrose and fructose were the main soluble sugar of watermelon fruit. In the forepart of fruit development, there was almost no accumulation of sucrose, but fructose and glucose contents were higher. Along with the developing of fruit, the main soluble sugar such as sucrose and fructose contents increased significantly. Sucrose mainly accumulated in the anaphase of fruit development and had higher contents in the fruits of Zaojiao/ Kangzhen-2 ,58.133mg/g. Total sugar contents of Zaojiao/ Xiyu and Zaojia were lower than others. Higher fructose contents was in Zaojia/Xiyu and Zaojia/Jiangjun, 32.62 mg/g 21.64 mg/g; while higher glucose contents was in Zaojia/Jiangjun, 5.76 mg/g.2.2 Changes of organic acid in different combinations are different during fruit development. Organic acid content in Zaojia/Kangzhen-2 increased obviously during fruit developing anaphase, and reached the highest when fruits matured, but others decreased rapidly. The highest content of organic acid was measured in Zaojia/Kangzhen-2, and it took turns of Zaojia/Xiyu, Zaojia/Jiangjun, Zaojia/Huazhen-2, Zaojia/ChaofengF1 and Zaojia.2.3 Changes of vitamin C and carotenoid of different treatments were consistent during fruit development, and the contents of them are higher in developing forepart and decreased rapidly during fruits swell. Changes of different rootstocks were different. Zaojia/Jiangjun changed greatly, and during the developing of fruit, the content increased gradually. Vitamin C and carotenoid contents had no significant difference in anaphase.
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