Abstract

Carbohydrates are the most important biochemical compounds in determining the quality of muskmelon fruit, and their accumulation in the muskmelon (Cucumis melo L.) fruits as substrate tub plants in solar greenhouse with different scion/rootstock graft combinations were studied. The results indicated that Zhongmi1/Shengzhen1 graft combination (GS) reduced all kinds of main sugars contents except galactinol and stachyose throughout the whole fruit development. However, the effects of Zhongmi1/RibenStrong graft combination (GR) on carbohydrates accumulation was less compared to GS, in which sucrose content was lower than that in self-rooted muskmelon (CK) only on 32 DAA, decreased raffinose content merely on 48 DAA, increased stachyose content only on 16 DAA and reduced total sugar accumulation dramatically. Grafting (GR and GS) enhanced starch content in the later fruit development. On the other hand, grafting GS significantly enhanced acid invertase or neutral invertase activity during the whole development, sucrose synthase activity only on 8 DAA and reduced sucrose phosphate synthase activity dramatically compared to CK during 16 to 48 DAA. Grafting GR increased acid invertase activity only on 24 and 40 DAA and sucrose phosphate synthase activity dramatically on 48 DAA. Grafting significantly increased alkaline α-galactosidase activity during 8 to 24 DAA; there were no significant differences between 32 to 48 DAA. Overall, considering the carbohydrate accumulation, Zhongmi1/RibenStrong graft combination was a superior graft combination, followed by Zhongmi1/Shengzhen1 graft combination.

Key words: Raffinose family oligosaccharides, scion/rootstock graft combination, galactose metabolism, alkaline α-galactosidase, raffinose, galactinol, stachyose, starch.