| Biocontrol of plant disease is welcomed by people for its long period of effect and environmentally-friendly characteristic. Most biocontrol agents are limited under laboratory or greenhouse conditions, however, few successful applications could maintain the biocontrol stable effect in the field. In order to provide important reference for field applications and commercialization development, many experiments have been finished. This study tested a variety of biocontrol agents on growth promotion and disease control trials under field conditions. Furthermore, detections to microorganism secretions about the characteristic were taken followed by pot experiments with strain 153 and SC11, as well as optimizing fermentation medium of strain SC11 with response surface method.Through the field experiment conducted for two successive growth seasons, potato, oil rape and broomcorn millet were chose to treat by biocontrol agents. Results indicated that different biocontrol agents were able to promote growth of different crops to various degrees. Compared with CK, 153 powder and suspension made an increase of 30.9% and more than 10% of potato yield respectively. When compared to the control, rotten potato in storage achieved with Fo47 suspension, SC11 power and 153 power were significantly(P < 0.05) reducted by over 50 percent. Moreover, the usage of seed soaking with 153 suspension and seed dressing with SC11 powder can enhance panicle length, tiller number, spike grain weight, stems rough, dry and fresh weight towards a great extent. Last but not least, irrigating roots by 153 suspension can also dramatically increase by 7% in thousand seed weight of oil rape.Through the pot experiments, results showed that strain 153 and SC11 can promote the potato plant height, dry and fresh weight of the overground parts, as well as underground parts, which showed a large increase over 400% in fresh weight of the underground portion compared with the control.Strain 153 can improve Ca, Cb and CT with the increase of 108, 225 and 175 percent and prevert oil rape from Sclerotinia sclerotiorum. Not only 153 but also SC11 showed a high effect to prevent oil rape from Sclerotinia sclerotiorum. Inoculated strain SC11 in advance, there was no disease spots on the leaf and a six-fold augment in the content of dissociated proline.Colonization of biocontrol agents in potato plants showed that strain 153 and Fo47 were capable of coloniziting within plant and the biomass in root were more than it in steam. What’s more, colonization in the root reached 0.5×103 cfu/g and 0.1×103 cfu/g treated by 153 power and Fo47 suspension respectively.Through the assay to secretion of rapid identification, it’s rudimentary confirmed the secretions of SC11 and 153. The SC11 with the ability of dissolving organic phosphorus can also secret protease, amylase, lipase, cellulose and IAA. Meanwhile, IAA and siderophore, some growth stimulating substance, were the components of 153 serections. Besides, response surface methodology were used to optimize the medium composition in shaker flask cultivation. The dry mycelial weight was achieved when the optimal concentrations(g/L) of starch, tryptone, KNO3, Ca Cl2, Mg SO4 and Mn Cl2 were 28.8, 1.0, 1.6, 0.83, 0.7 and 0.011.Studies demonstrated that strain 153 serecting IAA and siderophore can accumulate chlorophyllous contents, as well as biomass of aboveground and belowground plant. Accordingly, strain SC11 showed a serections of various enzymes, IAA and ability of dissolving organic phosphorus. Both of them displayed stable and effective effect on groth promotion and disease control. |
