| The disease of Poa pratensis leaf blight was used as the research object in this study, and its symptom, pathogen and biological characteristics, toxicity, antifungal endophytic bacteria were determined and identified, and the factors of inhibition was optimized in vitro. The main results were as follows:The disease was mainly infected with the upper leaves of Poa pratensis, which was usually started at the leaf tips and margin, and then formed a large dead spot that covered with a large number of small black spots. The colonie′s color was white at initial stage, and then the color from olive green to dark brown finally while cultured on PDA medium. Also, the orange particle droplets were produced on the colonies, and the wheel lines can be seen on the back of medium significantly. All the mycelium had diaphragm, and its color was colorless or light brown. The conidium shape was long ellipsoidal neurons, which was single cell(colorless) and had oil balls on its both sides. The size of conidium was 4.2×1.8 um ~ 7.7×4.8 um(average 5.8×3.4 um). The pycnidium shapes was globose, ovoid or oblong, even with orifice, and it size was 48.3×193.1 um ~ 38.5×139.6 um(average 106.0×86.4 um). Therefore, the pathogen of Poa pratensis leaf blight disease was identified as Peyronellaea glomerata that combined with it morphology characteristic and ITS sequence in this study.The results revealed that the optimum temperature for P.lomerata mycelium growth and spore production was 25℃, and optimum medium for mycelium growth was PDA, PSA and CAA, respectively. The optimum medium for spore production was CMA and Richard, respectively. Alternative light(12 h/12 h) and lightless or dark were the optimum conditions for mycelium growth and spore production. The optimum p H for spore production and spore germination were 7.0. Among carbon source, L-rhamnose and soluble starch were the best carbon sources for mycelium growth and spore production. Among nitrogen source, urea has significantly inhibitory effect to hyphae growth and spore production. The optimum temperature, alternative light and p H for P. lomerata conidium germination was 25℃, 6 h /6 h and 6.47, respectively. Also, the grass extract and liquid water were the optimum most conditions for conidium germination.Nineteen kinds of fungicides had better inhibitory effect on P. lomerata growth in vitro. The fungicides of 10% difenoconazole WP, 25% propiconazol EC, 0.15% tetramycin EC, 40% flusilazole EC and 43% tebuconazole SC had a significant inhibitory effect on P. lomerata growth, and it EC50 values were 0.1569, 0.3656, 0.3743, 0.3871 and 0.4303 mg/L, respectively. These five fungicides can be applied to manage P. lomerata in field.There were 32 strains endophytic bacteria from alpine grassland of qilian mountains grass have antagonism effect, and the bacteriostatic rate were over 55%, up to 76.55%. The best strains were 265ZY3, 263ZY4, 265ZY1 and 264AY3. The best strain 264AY3 was identified as Bacillus subtilis. The optimum fermentation conditions as follows: F culture(beef peptone 0.8%, yeast extract 0.5%, glucose 0.5%), p H 7.5, fermenta for 96 h, 20 m L in 150 m L triangle bottled fluid volume, inoculation quantity of 1%. |
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