| Melon(Cucumas melo.)is deeply loved by the Chinese people,but with the continuous expansion of its cultivation area,the damage of soil-borne diseases such as fusarium wilt is increasing.In this paper,we used the anti-fusarium wilt stock(Lagenaria siceraria var.hispida)"H04-1"(H)and the stock pumpkin(Cucurbita moschata(Duch.ex Lam.)Duch.ex Poiret)"Japanese cedar"(N)Grafting with the high-susceptible melon wilt melon cultivar "Good Luck11"(C),setting the scion self-root grafting combination(C/C),the stock grafting combination(C/H,C/N)and the rootstock self-grafting combination There are five root grafting combinations(H/H,N/N).Under the condition of inoculating melon wilt pathogen,gas chromatography-mass spectrometry(GC-MS)was used to determine the composition and relative content of the root exudates of each grafting combination,and to analyze specific active substances speculated to be related to disease resistance.The allelopathic effects of specific active substances were studied,combined with the effects of different rootstock grafting combinations on the resistance to fusarium wilt,rhizosphere matrix enzyme activity and the number of microorganisms,the physiological mechanism of grafted muskmelon root exudates and resistance to muskmelon fusarium wilt was described.The results of the study are as follows:1.Grafting with disease-resistant rootstocks can significantly improve the resistance of muskmelon seedlings to fusarium wilt.The incidence and disease index of C/H and C/N are reduced by 66.23%,59.77%,75.78%,58.94% respectively compared with C/C.,Reaching the resistance level of R(disease resistance).It was determined that the initial stage of onset,the peak period of onset,and the end of onset were the 3rd to 9th,9th to 17 th,and 17 th to 21 st days after vaccination,respectively.After inoculation with the pathogen of muskmelon fusarium wilt,the growth of C/C was inhibited.Grafting with disease-resistant rootstocks can effectively slow down the inhibitory effect of pathogens on the growth of grafted seedlings.After inoculation,the number of melon wilt pathogens in each grafted combination gradually decreased from the root system to the above-ground stem.The number of melon wilt pathogens in C/C roots,rootstock stems,and scion stems reached their peak during the peak period of disease,while C/H,C/N,H/H,and N/N peak at the beginning of the onset,and are much lower than the value of C/C peak period.2.After inoculation with the pathogen of muskmelon fusarium wilt,grafting with disease-resistant rootstock can increase the activities of urease,peroxidase and polyphenol oxidase in the rhizosphere matrix of grafted plants.After inoculation,the numbers of bacteria,fungi and actinomycetes in the rhizosphere cultured by different grafting combinations increased first and then decreased.Grafting with disease-resistant rootstocks increases the number of microbes in the rhizosphere and improves the microbial environment of the grafted plants.3.Root exudates of susceptible C/C promoted the growth of pathogenic fungus hyphae,and the inhibitory rate was-3.51%,while the root exudates of C/H,C/N,H/H,and N/N were significantly inhibited The growth of pathogenic fungus hyphae reduces the morbidity and disease index,and its antibacterial rate is 11.13% ～ 16.28%;the morbidity rate is lower than that of sterile water CK by 8.57% ～ 14.24%,and the disease index is lower than that of sterile water CK.10.80% ～ 15.26%.After grafting with disease-resistant rootstocks,the root exudates of grafted plants can significantly inhibit the growth of pathogenic fungus hyphae,and reduce the incidence and disease index of fusarium wilt.4.The root exudates of the grafted plants were analyzed and found that the C/C root exudates after inoculation contained 2,4-di-tert-butylphenol(DTB),dibutyl phthalate(DBP)and 2 The content of 2-methylene-bis-(4-methyl-6-tert-butylphenol)(MBP)is lower than that of uninoculated ones,and the content of C/H,C/N,H/ The relative contents of the above three substances of H and N/N all increased to different degrees compared with the uninoculated ones.It is speculated that they are the specific active substances for resisting disease rootstocks and enhancing the disease resistance of grafted seedlings to Fusarium wilt.5.Different concentrations of DTB,DBP,and MBP solutions have inhibitory effects on the growth of melon fusarium wilt pathogenic mycelium.The inhibitory rate is 12.80% ～26.65%.Among them,the 0.5 m M DBP solution is the best.Irrigation with different concentrations of DTB,DBP and MBP solutions can significantly reduce the incidence and disease index of melon fusarium wilt.The incidence and disease index decreased by 6.96% ～25.57% and 9.30% ～ 29.46%,respectively,compared with the control.The best is the 0.5 m M DBP solution.6.DTB,DBP,MBP solutions can promote the germination and seedling growth of melon seeds at low concentrations,but have inhibitory effects at high concentrations.Among them,0.5 m M treatment has a better promotion effect,while 1.0 m M MBP treatment can Showed as a certain inhibitory effect. |
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