Effects Of Trichoderma Aureoviride T2on Microbial Populations And Thescreening Of Antagonistic Strain

1. Trichoderma aureoviride T2was applied into soil to termly determne the microorganism quantity in soil samples during the growth of alfalfa. The results showed that Trichoderma aureoviride T2significantly inhibited alfalfa rhizosphere soil bacteria and fungi, and mainly caused population reduction; significant growth promoting effect on azotobacter, little effect on actinomycetes. In alfalfa harvest, the largest number of bacteria in the CK soil, reaching4.24×1010/g dry soil,3.56times higher than the soil before it was treatment,3.79times the number of Trichoderma aureoviride T2treatment group of soil bacterial communities; harvest time treatment of soil fungi reduced number of up to less than before treatment4.53times and8.20times less than the CK; quantity of actinomycetes in the treatment soil and CK wavy slowly rising, both in the number of no significant difference; azotobacter in the treatment soil was increased significantly and in the CK soil was slowly rising, the quantity of azotobacter in the treatment soil is3.01times of the CK in harvest.2. Trichoderma aureoviride T2was spraying in the alfalfa foliar surface by spray method to determne the microorganism quantity in alfalfa foliar phyllosphere. The results showed that the quantity of foliar phyllosphere microorganism was abundant, however, the difference of quantity among three microorganism and the quantity from high to low was in the order:bacteria> fungi> actinomycetes.Alfalfa foliar spraying Trichoderma aureoviride T2agents obviously caused microbial changes in the number,the number of foliar phyllosphere bacteria first slowly increased and then decreased,35d the number of CK foliar phyllosphere bacteria is33.54/cm2, while treatment is only6.13/cm2;the number of fungi was decreased and then increased,the number of CK foliar phyllosphere fungi increased from8.08/cm2to20.57/cm2, the actinomycetes has no significant change.3. Laboratory toxicity tests of six common fungicides and five common pesticides to Trichoderma aureoviride T2strain were carried out using the methods of mycelium growth. The results showed that the six fungicides and the five pesticides could inhibite effect on mycelium growth of Trichoderma aureoviride T2strain, and the inhibitory effect increased with increasing concentration of fungicides or pesticides, but different pesticides on the toxicity of the Trichoderma aureoviride T2strain mycelium.The mancozeb and cyhalothrin had the worst toxicity against, and their EC50values were221.14μg/mL and3.59μl/mL respectively;the procymidone and chlorpyrifos had the highest toxicity against, and their EC50values were26.24μg/mL and0.74μl/mL respectively.Through virulence regression equation and the results of EC50, the virulence strong sequence of the6kinds of fungicides for the experiment is as follows:procymidone>iprodione> carbendazim> chlorothalonil>triadimefon> mancozeb; the virulence strong sequence of the5kinds of pesticides for the experiment is as follows:chlorpyrifos> phoxim> avermectin> chloramine phosphorus> cyhalothrin.4. In order to obtain the antagonistic strains to procymidone, first of Trichoderma aureoviride T2strain by UV irradiation and selected mutagenic strains,then domesticatied on medicinal culture medium in different concentration(50μg/ml-800μg/mL), finally got the4strong antagonistic strains to procymidone:T2-1, T2-2, T2-5, and T2-6. After the10inoculation, colony growth rate mensuration, spores quantity mensuration and antagonism to Botrytis cinereac mensuration, the results showed that the4strains’ biological characteristics are steady, and the T2-6strains was significantly better than other3strains. Experiments showed that inhibition rate of compound of108cfu/g T2-6and800μg/ml procymidone(rate=8:2) to Botrytis cinerea was86.83%, significantly higher than108cfu/g T2-6and procymidome individuals.