Study On Conditions For Fermentation Of The Bioherbicidal Sclerotinia Minor Jagger

Sclerotinia minor is pathogenic to most broad leaf weeds. In regards of its ability to produce no or rare apothecia, and therefore airborne ascospores in the field which contributes to its safe use as a bioherbicide, S. minor is a suiTab. candidate for bioagent to control broad leaf weeds。Oxalic acid plays an important role in pathogenesis of a number of pathogens. Oxalic acid is believed to act: by direct disintegration of pectic substrate; by stimulating polygalacturonase activity, both by lowering the pH of the host tissues and by rendering the calcium-pectate complexes of the cell walls more suscetbile to hydrolysis; by the inhibition of polyphenoloxidase(PPO) through its binding with copper at the active center to form a sTab., inactive complex. Lack of PPO activity would result in a small amount of phenolic oxidation products which in turn protect the pectic substrates from disintegration.;by inhibition of the oxidative burst of the host plant,positive correspondence was found between oxalic acid concentration and virulence.Liquid state medium was optimized through one-factor experiment and orthogonal experiments. The suiTab. Richard medium contained (g/L): Sucrose 25g, Yeast 3g, KH2PO4 6g, MgSO4.7H2O 2g, Fecl3 0.02g. We choosed Initial pH, inoculum size and temperature as influencial factors to carried out the cultivation of fruiting body in which orthogonal vegression design was used with three factors and five levels. Accordingly, we found out the liquid fermentation conditions contained: initial pH was 5, inoculum size was 3 agar plugs, temperature and time for fermentation were 20℃and 6d.Millet was chosen for solid fermentation of Sclerotinia minor, Sodium succinate acid raised the oxalic acid concentration and virulence of the herbicide significantly. The solid fermentation conditions were optimized through one-factor experiment and orthogonal experiments. The suiTab. conditions contained: initial moisture content was 60ml, inoculum size was 2ml, temperature and time for fermentation were 20℃and 7d.Temperature had significant influence on viability and virulence. At lower temperature herbicide kept higher viability 3 month after storage, viability and virulence at -18℃was significantly higher than those at both 2℃and 22℃. Herbicide lost 100% of its viability and...