Difference And Mechanism Of Resistance To Meloidogyne Incognita Of Cucumber Rootstocks

Cucumber(Cucumis sativus L.) was one of the most important vegetable crops in ourcountry, because of Long-time continuous cropping of cultivation cause serious plant diseasesand insect pests. Root knot nematode wasone of the main cucumber disease, the growth ofcucumber will cut20%to30%, even sometimes will be totally lose after infected.Meloidogyne incognita is the main root nematode at the north of our country, but there are nocucumber resources could resistant it. So using resistant rootstock grafting is an effective wayto relieve the harm. In this study, evaluated the resistance of20rootstocks to Meloidogyneincognita, then preliminary study the resistant mechanism, in order to supply the theoreticalbasis to the production practice and breeding resistant variety. The main results were asbellow:1Twenty cucumber rootstocks collected from home and abroad were analyzed toevaluate their capacity in resistance to Meloidogyne incognita using natural identification andartificial inoculation identification. The result showed that all of the rootstocks weresusceptible and could be divided into three classes: low sensitive, middle sensitive, and highlysensitive through Clustering analysis; according to the value of membership function methods,‘Figleaf gourd’,‘Kurotane’ and ‘Eibulu’ had a stronger resistance capacity, while ‘Shiasuto’,‘Qingyan No.1’, and ‘xuezhenjingang F1’with a weaker one. Association of artificialinoculation identification with membership function methods could give more accurate result.2The Physiological and biochemical metabolism among the seedlings of nematode-lowsensitive cucumber rootstock variety ‘Figleaf gourd’, highly sensitive ‘Tianzhen’ andcucumber ‘Xintaimici’ after artificial inoculated with Meloidogyne incognita in this study.The result show that after inoculated with Meloidogyne incognita, roots and leaves of threematerials had higher reactive as the metabolism of active oxygen, phenylpropanoidmetabolism and pathogenesis-related protein metabolism. And the ‘Figleaf gourd’ had thehighest content, activity and growth, but the content, activity and growth of ‘xintaimici’cucumber were lowest.3With the method of artificial inoculates Meloidogyne incognita, evaluated the effect ofroot exudates of nematode-low sensitive cucumber rootstock variety ‘Figleaf gourd’, highlysensitive ‘Tianzhen’ and cucumber ‘Xintaimici’ on egg hatching. The results showed that,Not inoculated with M. incognita, the result of the root exudates of the three materials on egghatching were significant, the cucumber varity ‘Xintaimici’ had the highest egg hatching rate,‘Tianzhen’ was second, and ‘Figleaf gourd’was the least. After inoculating, the egg hatching rate of the three materials were higher than the one Non-inoculating, the amplification ofcucumber was biggest, and the ‘Figleaf gourd’ was smallest. As the growth time extended,the effect of the root exudate on egg haching was enhanced gradually.4With the method of artificial inoculates Meloidogyne incognita, Study the developmentprocess of juveniles in the root and rhizosphere of nematode-low sensitive cucumberrootstock variety ‘Figleaf gourd’, highly sensitive ‘Tianzhen’ and cucumber ‘Xintaimici’. Theresults showed that, at the beginning of the infection, the number of the juveniles in the threematerials roots were significant, the number in the cucumber root were the most, and the‘Figleaf gourd’was least. And all the juveniles in the roots could develop into wasp, so thetotal of nematode in the cucumber root was biggest, the ‘Figleaf gourd’ was smallest too. butthe ratio of the male and female of fourth insar larvae in the cucumber root was biggest, the‘Figleaf gourd’ was smallest. In the rhizosphere, the number of juveniles of ‘xintaimici’ wasthe most, and ‘Figleaf gourd’ was least; before the secondary infection, the number of theeggs presented the same characteristics.