| China is one of the most important tomato producting countries in the world. However,various pathogen diseases such as late blight and Fusarium wilt, caused by continous cropping had seriously hampered its development. LH-2010 A is a novel broad sprectrum F-containing benzamide fungicide, produced by Shandong united pesticide industry Co. Ltd. In this study,we tried to evaluate the control efficiency of LH-2010 A on Phytophthora infestans, Botrytis cinerea, Cladosporium fulvum and Fusarium oxysporum with indoor toxicity test, greenhouse and field bioassay, ascertain its influence on tomato plant growth, and preliminary assess its soil ecological effect by measuring its influence on number of soil cultivable microorganism,activity of soil enzyme, soil respiration, soil bacterial diversity and abundance of genes related to nitrogen circulation, to discuss the mechanism of LH-2010 A on disease control and field increasing. Our results would provide theoretical basis for its register on tomato plant and reasonable usage in field. The results were as follows:1. Laboratory toxicity results showed that the EC50 of LH-2010 A on P. infestans, B.cinerea, C. fulvum and F. oxysporum were 2.550, 2.502, 1.527 and 4.662 mg/L, respectively,direct control efficiencies were well, and LH-2010 A was an excellent broad spectrum fungicide.2. Results of High Performance Liquid Chromatography(HPLC) analysis showed that,soil treated LH-2010 A could be absorbed by tomato root and transplanted to upward part.Meanwhile, degradation dynamics of LH-2010 A in tomato planted soil were in accordance with the first order kinetics. Regression equations of 1, 2 and 4 folds of LH-2010A’s field recommended dosage were y = 3.685 e-0.24 x, y = 6.097 e-0.18 x and y = 10.32 e-0.13 x, with t1/2 4.50,4.95 and 5.57 days respectively.3. Greenhouse and field trial results showed that LH-2010 A could control soil borne blight, wilt and upward gray mold, leaf mold simultaneously via soil treatment, and higher dosage could provide better efficiency and longer lasting period. 21 days after treatment,control effect of highest dosage on 4 tomato diseases all exceeded 80%. Under field condition,50 days after soil treatment, 4 folds of LH-2010A’s field recommended dosage had exhibited control efficiencies of 66.67~70.76% for 4 tomato diseases.4. Greenhouse trials showed that, all tested dosages of LH-2010 A had no negative effect on tomato plant growth, and could improve defense enzyme(POD and PAL) activities and root vigor with higher dosages, which would help to interpret the effect of LH-2010 A on disease control and field improving. In field trial, higher dosage of soil treated LH-2010 Acould significantly increase tomato plant height and vigor 50 days after treatment. Compared with fluopicolide, 1, 2, and 4 folds of LH-2010A’s recommended dosage could increase tomato field yield by 14.6%, 23.3% and 32.0% respectively.5. Traditional methods were used to determine the effects of LH-2010 A on population of cultivable microorganisms. The results showed that effects of LH-2010 A on soil bacterial and actinomycetes numbers only had a short duration, the inhibition on fungus lasted to 40 days after treatment, and two disease pathogens Phytophthora and Fusarium were inhibited until 60 days after treatment.6. Results of soil enzyme activities test indicated that, soil urease, dehydrogenase, acid phosphatase and cellulose were firstly inhibited and then activated by LH-2010 A, soil invertase was activated, and catalase was inhibited. However, the influences were all temporary, and 60 days after treatment, soil enzyme activities in every treatment had no significant difference. Influences of LH-2010 A on soil enzyme were restorable.7. Results of soil respiration measurement showed that, 15 days after treatment, 100 folds of LH-2010A’s field recommend dosage had no significant negative effect soil respiration, and belongs to low or no actual harm grade to soil microorganism.8. T-RFLP results showed that, more T-RFs were inhibited 20 days after treatment, and inhibition effect disappeared gradually with time passing. During the whole period, some T-RFs were activated, such as T-RF 61 and T-RF 570, of which a number of beneficial bacteria related to nitrogen and nitrification were included.9. Real-time quantitative PCR analysis on abundance of soil nitrogen fixation gene nifH,denitrifying gene nirS, ammoxidation gene amoA, and results showed that, soil treated LH-2010 A could significantly increase abundance of soil amoA of bacteria(AOB in brief)and nifH, which was in accordance with results of T-RFLP. It is indicated that soil treated LH-2010 A could control 4 tomato diseases, and improve the multiplication of beneficial bacteria, to increase tomato field. |
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