| Tomato root knot nematode disease is a serious soil-borne disease,which can cause large scale yield reduction or even no crop.At present,chemical control is the main method to control this disease.The long-term extensive use of chemical pesticides is easy to cause"3 R" problems such as pest resistance(Resistanse),pesticide residues(Residue)and rampant pests(Resurgence).Therefore,the development of new biological pesticides and the establishment of efficient biological control system have become the focus of the disease control research.Crotalaria pallida Ait.is a traditional Chinese herbal medicine,and its root exudates have bactericidal and insect inhibitory effects.In order to clarify the mechanism of action of C pallida on tomato root knot nematode disease,to clarify the mechanism of action of C pallida on tomato root knot nematode disease and to explore its application potential in the control of root knot nematode disease,In this study,the inhibitory effect of root exudates of C pallida Ait.on southern root-knot nematode was determined,and the active components were identified.The effect of intercropping C pallida on tomato plant growth and the control effect of root knot nematode disease were clarified.The results are as follows:1.The larval mortality rate of nematode J2 reached 90%after 18 h treatment with the root exudates of C pallida The inhibition rate of egg hatching was 29.41%when treated with root exudates.The results of the taxis experiment showed that the amount of nematodes in the treated part was only 65.21%of that in the control part,which had obvious repellent effect.Treatment with root exudates for 24 h had significant effects on respiration,total sugar content,soluble protein content and acetylcholinesterase activity of nematode.Oxygen uptake,total sugar content,soluble protein content and acetylcholinesterase activity of nematode treated were 20%,67.68%,54.31%and 50.78%of those of the control,respectively.Microscopic observation showed that the body wall of the nematode was damaged,and spherical or rod-like vacuoles appeared in the body.2.The active constituents of the root exudates of C pallida were isolated by chromatography,and the effects of the absorption peak substances on the nematode were collected and tested.The results showed that two absorption peaks were obtained by separating the root exudates from the root exudates.The mortality rate of the nematode was 76.21%after the first absorption peak was detected,and 66.43%after the second absorption peak was detected.LC-MS method was used to analyze the absorption peak substances.The results showed that the first absorption peak contained demethylmenaphthoquinone,hematoporphyrin and isorhamnetin.The second absorption peak consists of wilforine,ginkgophenolic acid and α-etoposide.3.Treating seeds of horticultural crops with root exudates of C pallida showed that the germination rate of pepper seed was increased by 10%;The results showed that the growth indexes of tomato increased significantly except plant height.The aboveground fresh weight increased from 58.46 g to 91.41 g,and the stem diameter increased from 0.77 cm to 0.99 cm.In addition to chlorophyll content and root-shoot ratio,the above ground fresh weight increased from 20.84 g to 47.25 g,root fresh weight increased from 3.52 g to 6.61 g.The root length and fresh weight of Chinese cabbage increased from 16.5 cm to 18.93 cm,and fresh weight increased from 0.37 g to 0.51 g.It had obvious inhibitory effect on the growth indexes of the cabbage.Plant height decreased from 16.2 cm to 13.65 cm,and fresh weight above ground decreased from 8.73 g to 4.64 g.We also carried out field interplanting experiments between C pallida and tomato,and the results showed that the growth index of the underground part of tomato was significantly improved,including the root length increased from 31.75 cm to 34.18 cm,and the fresh root weight increased from 19.38 g to 21.64 g.This study also tested the effects of intercropping of C pallida and tomato on soil fertility and enzyme activity indexes.The content of soil available nitrogen increased by 33.09%,the content of sucrase and urease increased by 17.22%and 98.85%,respectively.In addition,the root exudates of C pallida had inhibitory effect on the mycelium growth of Fusarium wilt of cucumber,the inhibitory rate was 8.49%.4.Through the pot and field interplanting experiments,The number of root-knot nematodes and eggs in rhizosphere,rhizosphere and root surface of tomato were significantly decreased.The number of eggs on the root surface of soil decreased by 47.11%and 58.12%,respectively.The amount of eggs on the root surface of interplanted soil decreased by 43.44%and 54.76%,respectively.At the same time,the number of root-knot nematodes and eggs in tomato roots infected by root-knot nematodes decreased significantly,the number of eggs in tomato roots in pot decreased by 68.93%and 85.74%,and the number of eggs in tomato roots in field decreased by 32.99%and 121.97%.The egg hatching rate in potted tomato roots decreased by 7.07%and that in field tomato roots decreased by 7.29%.The disease index of root knot nematodes in potted and field decreased by 21.67 and 11.33,respectively.This study laid a foundation for the agricultural application of C pallida. |
PDF Full Text Request