Study On Biological Characteristics Of Sclerotinia Sclerorium And Sclerotinia Disease Resistance In Sunflower Cultivars In Xinjiang

Thirty Sclerotinia strains were collected and the biological characteristics as well as their pathogenicity were tested. It was showed that the growth speed of hypha, sclerotinia production and the pathogenicity of strains had little relation with host and geographical location. The ability of oxalic acid production of strains had positive relation with the pathogenicity. In order to study the nutrition aptness, 8 kinds of culture mediums were tested and the result showed that S. sclerotinia strains grew better and more vigorously on PDA and PSA mediums than on the other mediums. Research on growing conditions of 6 representative strains demonstrated that pH in neutral and a little acidic and temperatures at 20℃are optimal for strains growth. Study on the esterase isoenzyme of strains showed that there had certain difference in esterase isoenzyme and the difference had certain relation with the geographical source and host of 30 strains. Difference in the esterase isoenzyme among S. sclerotorium, S.minor and S. trifoliorum were greatly obvious, indicating the esterase isoenzyme could be used as a kind of supplementary means for identifying these three similar species. In order to make clear the original infection source of sunflower Sclerotinia rot, hypha and sclerotinia of 6 S. sclerotinia strains were buried underground, and the sclerotinia could successfully survive the winter either buried at 15 cm or 30 cm, but it should be tested again for ascertaining whether hypha could survive the winter in Xinjiang. In addition, research on the production of apothecia of S.sclerotorium and observasion of ascospores indicated that the sclerotinia of Sun-1 strain could germinate and produce apothecias on both sand and sand & earth after the low-temperature induction, but it produced more apothecias on the sand.At present, no sunflower varieties were immune or high resistant to S.sclerotorium. The disease was controlled mainly by crop rotation and breeding resistant varieties. There were 3 or 4 sclerotinia disease types on sunflower, and there had no uniform and effective means although many means for identificating the resistance of sunflower varieties were reported. So, it was necessary to screen the effective means and improve and optimize the reported means unceasingly. 4 means including diseased-soil-potting,stem mycelial attachment, hull inoculation and root oxalate-dipping were adopted on 3 sunflower (Helianthus annuus L.)...