Study On The Effects Of Different Rootstocks Grafted On Physiological And Biochemical Characteristics And Quality In Watermelon

The effects of seventeen different kinds of rootstocks on the growth, development, resistance, yield and quality of watermelon were studied in this research to probe into the choice of stock for watermelon and guide the producing practice. Hongjinbao and Koukoucui were taken on the CK.In the paper changes of the activity on peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT) and superoxide dismutase (SOD) and the contents of malondialdehyde (MDA) in grafted seedlings were studied simultaneity. The results were as follows:1. Effects of rootstocks on the growth and development of grafted watermelon: different grafting treatments had different grafting compatibility. The cions grafted on Jiewen, Zhongzi gourd, Changzhenlishi, Ansheng gourd, Hanzhenyihao having better grafted compatibility, and their survival rates were also higher than others. All grafted treatments grew better than own-rooted watermelon seedlings (CK).2. Grafting treatments promoted the resistance of watermelon to watermelon's wilt disease effectively: the grafted seedlings had the lower incidence of blight than CK. The research suggested the gourd-rootstocks had the greatest resisting power to blight, and then followed the pumpkin-rootstocks and the wild watermelon-rootstock , while the own-rooted watermelon seedlings had the lowest power. Above all, gourd was a good kind of watermelon's rootstock in local area.3. The connection between enzyme activities and resistance of grafted seedlingsThe POD activities of different grafted watermelon's leaves was greater than CK, and it's maybe in connection with good growth of grafted seedlings. The POD activities of Shuofeng/Hongjinbao and Shoufeng/Koukoucui were respectively 374.300 units.g^-1FW and 425.125 units.g^-1FW , which were higher than that of CK, having significance of difference between them. Xiaohuapi/Hongjinbao had the greatest POD's activties, that's 30.55 0.01ΔA.g^-1.min^-1, and Hongjinbao(CK)'s merely 200.01ΔA.g^-1.min^-1.The PPO activity of Hanzhenyihao/ Koukoucui(29.45 0.01ΔA.g^-1.min^-1) was also higher than CK. Both of grafted seedlings and own-rooted watermelon seedlings had lower CAT activities, and there was no obviously difference. But CAT activities of grafted watermelon's leaf were still higher than CK, Zhongzi gourd/Hongjinbao's 12.744mgH₂O₂.g^-1FW.min^-1and Zhongzi gourd/Koukoucui's 5.888mg H₂O₂.g^-1FW.min^-1.The SOD activity of Hongzhenwang/Hongjinbao was 112.370 units.g^-1FW.h^-1, Comparing with it, Hanzhenyihao/Hongjinbao was just 65.785 units.g^-1FW.h^-1. And in the grafted treatments that the cion was Koukoucui, Xiaohuapi gourd/Koukoucui had the highest SOD activity, which is 160.468 units.g^-1FW.h^-1.The MDA contents of grafted seedlings's leaves were observably lower than CK, and it indicated the degree of membrane lipid peroxidation was more lower in grafted watermelon. That was in connection with the activities of protective enzymes, while which were in a high level could protect cytoplasmic membrane, resulting in the lower content of MDA in grafted seedling's leaves.4. Watermelon yields were significantly enhanced by grafting: in this paper, watermelon yields of all grafting treatments were obviously higher than CK. Taking Zhongzi gourd as rootstock, these grafted treatments produced the highest yield, up 60% than CK. This was in accord with the growth of gourd's grafted treatments.5. Effects of rootstocks on fruit quality of grafted watermelon: the contents of soluble solid, soluble sugar and vitamin C varied from stocks to stocks. The contents of soluble solid in Changzhenchaofeng/Hongjinbao, Changzhenchaofeng/Koukoucui differed greatly from CK. While Shoufengguazhen/Hongjinbao.Shoufengguazhen/Koukoucui had more soluble sugar and vitamin C than CK. These suggested the effects on fruit quality of grafting differing from rootstocks.6. Effects of rootstocks on sensory quality of grafted watermelon: in this study there were no significant differences on water content, taste, the color of pericarp and pulp, quality, maturity and the number of seeds between all of grafted treatments and own-rooted watermelon seedlings. The grafted treatments of Jinfenghuang rootstock had few of vegetable fibre, which sensory quality was inferior to CK. While all the other grafted treatments's sensory quality excelled CK.