| Stem rot of rape is a world-wide disease caused by 5. sclerotiorum, which affects the production of rapeseed seriously all around the world. As a result, the breeding and application of varieties resistant to 5. sclerotiorum has attracted increasing attention of the scientists and researchers in the world. The author has made some tentative studies on the screening of resistant resources of rapeseed to S. sclerotiorum, the resistance mechanism of rapeseed to 5. sclerotiorum and the pathogenesis mechanism of 5. sclerotiorum, with the expectation of providing foundation for resistance breeding .The main results are follows:Rapeseed (Brassica napus} seedlings were treated with Duo-Xiao-cuo and sou je an at the concentration of 2g/kg Cd, Ig/kg Cd and 0. Ig/kg Cd. The results were that SJA at the concentration of 0. Ig/kg Cd had no significant effects on growing rate of rapeseed seedlings and leaf area of rapeseed seedlings, but resuced the hight of rapeseed seedlings, and the hight of rapeseed seedlings was keep at a moderate level succeed in averting an hight rapeseed seedings for inoculation and determination.The determination with myceliam inoculation of 133 rapeseed hybrid combination resistance to S. sclerotiorum was showed that there were llhigh-resistant hybrid resources, 10 middle-resistant hybrid resources, 44 low-resistant hybrid resources. 42 low-susceptible hybrid resources, 17 middle-susceptible hybrid resources, 9 high-susceptible hybrid resources. The percentage were 8. 27%, 7.52%, 33.08%, 31.58%, 12. 78% and 6. 77% respectively. Of them, Zhong R - 888, M004, and 98C40 were high resistant and high susceptible parents. Ganyou 5/M004,M004/ Ganyou 5 , Zhong R -888/98C40, Ganyou 5/M004//M004, 98C40/M004//M004 and 085/98C40//085 were high resistant hybrid combinations. High susceptible hybrid combinations were Ganyou 5/M004// Ganyou 5, Ganyou 5/083// Ganyou 5, Ganyou 5/ Zhong R-783// Ganyou 5, 98C40/083//98C40, 98C40/ZhongR-783//98C40, 083/ Ganyou 5// Ganyou 5, 083/98C40//98C40, Zhong R - 783/ Ganyou 5// Ganyou 5. It was obvious that resistance to sclerotinose between B. napus lines had significant difference. The resistance hybrids, which were the offspring of high resistant parents and the first and second gener ations, of back-cross affected by the parents; and the high resistance was partial dominant. There were resistance difference between B. napus gentotypes. using high resistance parents to cross and back-cross, strengthening separation, identifying and selecting the resistant seedlings in early generations, we could breed high tolerance varieties.Seven resistant varieties in eluding M004, xiangYoulS, zhong R-888> zhong R-783> 083, 084, 085 and four susceptible varieties including 98c40, sw038, Can You 5 Hao, H52-1 were chosen for biochemical measuring in different time after inoculation with 5". sclerotiorwn. The results revealed that there was no relation between the activities of peroxidase and phenylalanine ammonia lyase resistance of rapeseed to S. selerotiorum before inoculation with SS5, But the activities of polyphenoloxidase and superoxide diamutase in resistant varief ies leaves were much higher than that in susceptible varieties leaves, before inoculation with SS5. The activities of peroxidase, polyphenolo- xidase, superoxide diamutase and phenylalanine ammonia lyase increased and showed two peaks in six diseased rape resistant varieties' s leaves, but two susceptible varieties showed only one peaks in diseased rape varieties' s leaves. Isosuperoxide diamutase experiment showed high-resistant varieties have eight bands more than middlesusceptible varieties , nine bands more than high - susceptible varieties and five bands more than low-resistant variety. There weren' t new isoperoxidase bands occurred in resistant varieties and susceptible varieties after inoculation with SS5. The isoperoxidase bands A was heightened in resistant varieties after inoculation with SS5. It had little effect on the number of the isoperoxidase bands .
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