Study On The Biological Characteristics Of Coniothyrium Minitans And Its Biological Control Of Oilseed Rape Stem Rot Caused By Sclerotinia Sclerotiorum

The sporulation and biomass dry weight of Coniothyrium minitans were greatly affected by C sources and N sources. However, the C sources and N sources which obtained an increase of biomass dry weight were not always the same ones as what got the greatest amount of conidia.On the contray,there were many C sources and N sources whose conidial production was negatively correlated with biomass dry weight.Although monosaccharide was usually the best C source nutrient,in which there was great difference.Also,the ratio of C to N affected biomass dry weigh and sporulation of Coniothyrium minitans,.the effects depended on what C source and N source were used.In general, sporulation increased with C:Nand biomass dry weight decreased or had no significant change withC:N.The effects were dependent on the conbination of C source and N source.Hyphal extension occurred over a temperature range between 10℃ and 30℃,with the optimal at 20℃ for sporulation and hyphal growth.Light had no effect on conidial production and hyphal growth,but it could improve the germination rate of Coniothyrium minitans.Hyphal extension occurred over a ph range between ph3-ph 10,while the ph range for sporulation was between ph4-ph9,with the optimal for both at ph6.The lethal temperature was 40℃-45℃10min.Relative humidity above 94% was necessary for hyphal growth. conidial germination.and sporulation.Conidial germination occurred over a small ph range,between ph4-ph6.As relative humidity was raised, conidial germination and sporulation also increased.Whether spraying conidial suspension of C. minitans on the petals of oilseed rape at early bloom or at full bloom,no disease control of oilseed rape stem rot caused by Sclerotinia sclerotiorum was obtained, high concentration of conidia suspension could inhibit the spread of lesion on the stem and leaf to some extent.Conidial germination of C. minitans on the petals of oilseed rape was inhibited by microorganisms colonizing on the petals. As time went on,the survival rate of C. minitans on the petals of oilseed rape was on the decrease.According to the relationship between the time and the survival number of conidia of C. minitans on the petals of oilseed rape,there was a regression expression(y=6.858-0.0701x).