Study On Biological Control Of Camellia Gray Spot By Bacillus Amyloliquefaciens

Camellia gray spot infected by Pestalotiopsis guepini (Desm.) Stey was a damage disease, which caused leaves and flower buds falling off. At present, the control methods against it were mainly reinforcing manages, cleanning water and spraying chemicals. Even if the control was obtained at right now,but enviourment was seriously polluted, the humans and animals were endangered,it also only could control the seeming damages. So the non-pollution biological control was needed to study immediately. In this paper, the colonization rules by the method antibiotic marker and the effects of biological control in the filed of Bacillus amyloliquefaciens were researched on the basis of selecting the optimal medium condition for producing antibacterial substance was studied too. The results were mainly as follows:1. The optimize fermentation condition of Bacillus amyloliquefaciens was studied. First, the best carbon and nitrogen source were selected which based on NA culture medium which were dextrose and peptone. Second, according to the orthogonal experiment and variance analysis, the best growth conditions of Bacillus amyloliquefaciens were indicated:beef extract 3g, peptone 4.375g e, dextrose 0.5g, pH 6.0, inoculation volume 2ml and bottle volume 125ml in 300 ml triangle bottle, with the shake culture 25℃. The growth curve was showed the best cultivated time was 72h. along with the relationship of resistance against the pathogen.2. The mutation strain Bacillus amyloliquefaciens which resisted to streptomycin 500μg/ml was obtained by the conventional antibiotic marker. Then it was prepared different concentrations for colonization test in order to find the best concentration for the biological control. The result showed that the marked strain had higher stability, which could colonized quickly on and in the leaves of camellia.From the colonization amounts of the original bacterial suspensions with high concentration were larger than those of the low concentration, especially the amount in the leaves was highest and the alive deadline was longest, which reached highest on the 8th d and kept high level (3.2×105cfu/g) on the 40th d. But the amount in the leaves was slower, which reached highest on the 16th d and kept level(5×102cfu/ml) on the 30th d. In the colonization effects about pathogen to biocontrol bacteria, it had great effect on leaves at a later stage, but, no effect in lesves.3. The field test of biological control of camellia gray spot by B. amyloliquefaciens showed that the infection index of pathogen contrast was very high, and the blank contrast hadn't been infected and the excellent effect was obtained. Moreover, in the conception of time, the control effect had a tendency that had enhanced after appreciably declining, which reached the highest level on the 8th d and then kept stably; in the inoculated way, the treatment of inoculated bacterial suspensions firstly was best, and the effect was 75.35% that was significantly higher than the others; in microbes influenced the control effect on the leaves, the amount on the original leaves was lower than that on the sterile leaves, but the difference was not significant.