The Research Of Graft On Overcoming The Continuous Cropping Obstacle Of Pepper In Protected Production

With the development of facility cultivation, the continuous cropping obstacles become more and more severe. Grafting as an effective method overcoming cropping obstacles has been widely used on cucumber, tomato and other kinds of vegetables, while there is little use on pepper. In this experiment, we get three pepper materials as root stock by comparing the growth and the resistance ability to Phytophthora capsici among fifteen pepper materials. We conducted six graft treatments with two grafting methods(cleft method and attaching method) on the three pepper root stock materials to research the healing process, survival rate, and efficiency of grafts. In addition, we collected and analyzed the growth index, the change of protective enzyme activity in the leaves, yield and quality of fruit of graft pepper, the distribution of rhizosphere soil microbial community and the change of soil nutrients. We researched the effect of graft on overcoming the continuous cropping obstacle. The main results were as follows:1. Three stocks for grafting were screened from fifteen different species of pepper by comparing the growth and the resistance ability to Phytophthora capsici. They were “K-7”, “Yuyixianla108”, “Xinxiya” which were more robust and had the stronger resistance ability to Phytophthora capsici.2. The three root stocks unites two grafting methods to form six grafting treatmengs.The grafting survival rate of all the grafting treatments were 80% and more. The survival rate of cleft grafting method was higher than attach grafting method, while the grafting efficiency of attach grafting method was higher than the cleft grafting method. The healing progresses of two grafting methods were same observed by paraffin section, which included the emergence of septum, the formation of callus and the differentiation of the tube. But there was slight difference in healing time duration between two grafting methods.3.After inoculation, the disease incidence of CK was 91.67%, while the grafting treatments has showed high resistance ability to Phytophthora capsici, and the disease incidence of E,B,F was 0,4.17%,4.17% respectively. In addition, grafted pepper showed higher SOD, POD, PPO activity in leaves compared with CK after inoculation, and treatment B, E were higher than other grafting treatments.4. All the grafting treatments facilitated the growth of pepper. The plant height and stem diameter of E were 39.83% and 19.07% respectively more than CK on the 48 th days after transplant. The plant height of B and the stem diameter of A increased by 31.16% and 10.84% respectively compared with CK. Moreover, the chlorophyll content and root activity of grafting treatments were significantly increased. The chlorophyll content of B and C got 3.29mg·g-1 and 3.13 mg·g-1 on the 36 th days after transplant, which were higher than CK. The root activity of E was significantly promoted and the increasing rate was 73.08% compared with CK on the 48 th days after transplant.5. Compared with CK, grafting treatments changed microbial structure in rhizosphere of pepper, with increased of bacteria, decrease of fungi. The bacteria number of B and E got 4.03×108cfu·g-1 and 3.65×108cfu·g-1 on the 60 th days after transplant respectively. The pepper absorption of soil available nitrogen, phosphorus and potassium in the soil with grafting treatments were significantly promoted. The grafting treatments had smaller decrease rate of available nitrogen, phosphorus, potassium than CK with the increase of transplant time.6. The quality and yield of pepper were increased by grafting. The content of vitamin C and soluble protein were increased, while the content of nitrate was decreased, compared with CK. The length and diameter of grafting pepper were increased compared with CK, moreover, the treatment B and C were higher than other grafting treatments. In addition, the yield of B, C, E increased by 20.87%、28.27% and 33.50% compared with CK.