EFFECTS ON CARBOHYDRATE AND AMINO ACIDS ACCUMULATION IN MUSKMELON FRUIT (CUCUMIS MELO L.) WITH DIFFERENT GRAFTING ROOTSTOCKS

Abstract

Effects on the carbohydrate and amino acids accumulation in the muskmelon fruits as substrate tub plants in solar greenhouse with different scion (Cucumis melo L. 'Zhongmi 1')/rootstock (Cucurbita maxima ×moschata) grafting combinations are under study. The results indicate that G1 ('Zhongmi 1'/'Riben Strong') and G3 ('Zhongmi 1'/'Shengzhen 1') increased yield by 16.78 and 20.8% on 42 DAA (days after anthesis) and by 18.51 and 26.29% on 50 DAA respectively. G3 reduced sugar accumulation, activity in the synthesis direction of sucrose synthase and sucrose phosphate synthase activity but increased invertase activity significantly during 34 to 50 DAA. On the contrary, G1 increased sugar content with the increase of sucrose phosphate synthase activity on 50 DAA, which indicated that grafting influenced sugar accumulation by changing sucrose metabolic enzyme activities. On the other hand, G1 increased significantly the contents of threonine, glutamic acid, methionine, isoleucine and lysine in muskmelon mesocarp, but decreased the contents of alanine, cysteine and histidine. G2 ('Zhongmi 1'/'Quanwang') dramatically enhanced the contents of threonine, methionine, tyrosine and lysine in muskmelon mesocarp, but lowered the contents of alanine, cysteine and histidine. G3 significantly increased the contents of threonine, serine, glutamic acid, glycine, methionine, phenylalanine, arginine, isoleucine, leucine, tyrosine, lysine and histidine in muskmelon mesocarp, but decreased the contents of alanine and cysteine. On the whole, grafting changed the contents of all amino acids except valine, influencing the fruit flavors. In conclusion, 'Zhongmi 1'/'Riben Strong' grafting combination was more appropriate for high fruit quality as followed by 'Zhongmi 1'/'Shengzhen 1' and 'Zhongmi 1'/'Quanwang' graft combinations.