Effect Of Melon Interstock On The Growth And Fruit Quality Of Grafted Cucumber

Cucumber, a species of worldwide popular vegetable with large cultivation area, strong adaptability and different forms and stubbles of cultivation, is the main vegetable in Northern protected lands. Recently the rapid development of protected cultivation has played a significant role in improving the agriculture benefit, increasing peasant income and prospering rural economy. The land-intensive-use mode of production not only satisfies the needs of our national people, but also becomes the pillar industry in some areas and greatly increases the peasant income. However, due to the high cost of greenhouse and problems of rotation and cropping, the continuous cropping soil in greenhouse results in many problems including serious soil-borne diseases such as fusarium wilt and blight, and secondary salinization, which have significantly decreased the yields and benefits. Grafting, as an effective way in controlling soil-borne deseases and overcoming the obtacles of continuous cropping in protected lands, has become an important technology for winter cucumber production in greenhouse. Grafting inevitably affects the fruit quality of cucumbers, therefore, in order to reduce the impact of rootstocks on fruit quality of cucumbers, breeding researchers have done much to screen out fine rootstock varieties but without significantly improving the cucumber fruit quality. Therefore, it is imperative to find a new way of grafting to improve the cucumber quality and keep its resistance as well. Our research aims to improve the cucumber fruit quality by investigating the effect of interstock grafting on the content of bleeding sap, the characteristic aroma matter and other various quality indices of cucumber.Effects of interstocks on the plant growth, bleeding sap and fruits quality of the grafted cucumbers were studied with interstock of'Elizabeth'melon, which scions were'Zhongnong No.14'and rootstocks were'Zhenyoumei'pumpkin. The main results were as follows.1. Grafted cucumbers grew better and had a higher production. The length and breadth of grafted cucumbers and self-rooted cucumbers both increased quickly after flowering 3-9 days, while the breadth growing become dominant after flowering 12days. The index of fruit shape increased first and then decreased in grafted cucumbers. The traditional grafting decreased the index of fruit shape, increased the weight of single fruit, lengthened the fruit stem/fruit and lowered the marketability. Grafted cucumbers with melon interstock had a higher index of fruit shape and a better fruit marketability than traditional grafted ones. Compared with self-rooted cucumbers, the grated ones with melon interstock significantly improved the length, breadth and average weight of single fruit, while the index of fruit shape and the length of fruit stem/fruit had no significant difference.2. Grafted cucumbers significantly increased the bleeding sap. No significant difference in bleeding sap existed between the grafted cucumbers with melon interstock and the traditional grafted ones, which both had a significant higher content than that in the self-rooted ones. The traditional grafting significantly improved the absorption of nitrogen and reduced the absorption of potassium ion, which may result in the deterioration of cucumber fruit quality. Keeping two true leaves of the melon interstock significantly increased the contents of bleeding sap and improved the asorption proportion of mineral nutrients. The contents of soluble sugar in the interstock grafting were significantly higher than those in the traditional grafted treatment, whereas the interstock of melon with two true leaves significantly increased the contents of the soluble proteins and free amino acids, which had no significant changes in traditional grafted cucumbers.3. Traditional grafted cucumbers had a significant lower soluble sugar, Vc and free amino acids, no significant change in soluble proteins, soluable solids, dry matter and flavonoids, and a higher content of titratable acid and tannin than those in self-rooted ones. Compared with the traditional grafting, the interstock grafted cucumbers had an obviously higher content of soluble sugar, soluble proteins, Vc, dry matter, soluable solids, free amino acids and flavonoids, and a significantly lower content of titratable acid and tannin. Meanwhile, the contents of soluble content, Vc and soluble solids in the interstock grafting were significantly higher than those in self-rooted treatment, whereas the contents of flavonoids and dry matter had no significance and the titratable acid and tennin were obviously lower in interstock grafted cucumbers. Keeping two true leaves of the melon interstock significantly increased the contents of soluble proteins, free amino acids, flavonoids and dry matter. 2E,6Z-propylene aldehyde was one of the important aroma matters in self-rooted cucumbers, with the relative content up to 17.17%. No 2E,6Z-propylene aldehyde was tested in traditional grafted cucumbers, while interstock grafted cucumbers especially those grafted with two true leaves of the melon interstock not only reduced the effect of grafting on the fragrance, but also increased four kinds of ester, that is, 2- hydroxyl - benzoic acid - methyl ester, hexyl benzoate, dibutyl phthalate and isodecyl formate.Grafted cucumbers with melon interstock grew better and had a higher fruit quality, while keeping two true leaves of the melon interstock had a better effect by taste evaluation, which was in accordence with the experiment results and analysis of the indices of fruit quality. Grafting with the melon interstock can reduce the adverse effect of the pumpkin rootstock on cucumber fruit quality, and thus is a new method for high quality production of cucumber in greenhouse.