Preliminary Research On Nutritional Physiology Of Sclerotinia Sclerotiorum (Lib.) De Bary

Rape Sclerotinia stem rot is the most important disease on oil seed rape.In order to clear the nutrition physiology of the pathogenic fungus,Sclerotinia sclerotiorum,and to provide further the experimental evidences for the research of sclerotinia sclerotiorum and the nutrition control of the disease,this paper deals with the nutrition of carbon and nitrogen sources and the effects of trace elements such as B,Zn and Se on the growth rate and the production of sclerotium.The main results obtained are as follows:1.The influences of different medium on the growth rate of Sclerotinia sclerotiorum and the production of sclerotium12 strains of sclerotinia sclerotiorum from rape of anhui were tested as strains,it measured the influence of 5 kinds of medium including PDA,PSA carrot medium,oats medium,sweet potato medium on the growth rate and quantity of sclerotinia sclerotiorum,the diameter of sclerotium was measured after culturing 2days in strains and record the number of sclerotiumon at the 7th day 14th day and 30th day.The results of this experiment presented that it's best for most of sclerotinia sclerotiorum to grow in PSA medium,it is also the best one that its number of sclerotia is higher than others,which means it's best for almost all of the growth of sclerotinia sclerotiorum and the formation of sclerotium.2.The influences of different carbon and nitrogen source on the growth rate of Sclerotinia sclerotiorum and sclerotium productionBased on the Czapek-Dox Agar,which is made from different carbon source and nitrogen source medium,replacing the sucrose,nitrate with carbon source and nitrogen source in this culture medium,then culture it in darkness with temperature of 25°.Measure the diameter of colony 2 days later,record the number of sclerotium at the 7th day,14th day and 30th day.The results of this experiment presented that sucrose is the best carbon source together with pep-tone is the best nitrogen resource on the growth of sclerotinia sclerotiorum and formation of sclerotium.3.Effects of B on the growth rate of Sclerotinia sclerotiorum and sclerotium productionAdd K₂B₄O₇₅H₂O to the melting PDA.Confected the liquor of 0.01,0.05,0.1,0.5,1,2,4,8,16mg/L.Then inoculated 12 strains sclerotinia sclerotiorum with above mentioned medium with sclerotium,cultured it in darkness with the temperature of 25°.comparing to PDA medium without K₂B₄O₇₅H₂O.Measured the diameter of bacterial colony after 2days.Recorded the number of sclerotium on the 7th day,14th day,30th day.The results of this experiment presented that it can promote the growth of hypha when at low concentrations?0.01mg/L,0.05mg/L?,but control the growth of hypha when at high concentrations?0.5 mg/L¹6mg/L?.The higher the B,the more obvious inhibition on hypha.B has inhibitory effect on the sclerotium production.The inhibitory effect increases with the increasing of B concentration ranging from 2 mg/L¹6mg/L.4.Effects of Zn on the growth rate of Sclerotinia sclerotiorum and sclerotium productionTake the same method to measure except for different concentration medium with zinc resource.The results of this experiment presented that it can promote the growth of sclerotinia sclerotiorum during the concentration from 0.01 to 4.0mg/l.Compared with various medium,the sclerotium production was slower than control group which indicated that zinc has an inhibition growth effect on the sclerotium production at this range of concentration.5.Effects of Se on the growth rate of Sclerotinia sclerotiorum and sclerotium productionPrepared different medium with sclerotium which was added Na₂SeO₃ into molten PDA medium,then inoculated 12strains sclerotinia sclerotiorum with above mentioned medium with sclerotium,cultured it in darkness with the temperature of 25°,comparing to PDA medium without Na₂SeO₃.The results of this experiment presented that compared the growth of sclerotinia sclerotiorum which was mixed a low concentration of Na₂SeO₃?<0.01mg/l?with control group,it's obvious that it had a promotion effect on the growth of sclerotinia sclerotiorum,the sclerotium can be formed in 7 days which is quicker than others.Whereas with a high concentration of medium with selenium,it had an inhibition effect on the growth of sclerotinia sclerotiorum,and the higher concentration it is,the higher inhibition rate it is.Besides,the shape of sclerotinia sclerotiorum changed obviously when the concentration of selenium beyond 10mg/l after observing.Compared with control group sclerotinia sclerotiorum was shorter and thicker,sclerotinia sclerotiorum showed a distortion along with malformation shape.Additionally,the results also presented that at the range of the concentration with selenium of this experiment?0.01mg/l¹00mg/l?,selenium has an inhibition effect on the formation of sclerotium,and sclerotium can't be formed when the concentration of selenium reached 80mg/L.