Control Effect Of Bio-inoculant To Diseases On Rapeseed And Zucchini And Its Growth Promoting Capacity

Plant disease is that there is a series of morphological, physiological and biochemical pathological changes so as to hinder the normal growth and development process in plants, and thereby affect the economic benefits in the biological or non biological factors. Among all diseases, sclerotinia rot of colza(Sclerotinia sclerotiorum) is a worldwide disease. The disease seriously affects the yield and quality of rapeseed in rapeseed producing areas in China. One of the pathogens of root rot of summer squash is Fusarium oxysporum that has strong saprophytic competition ability in soil, and can survive for a long time, so it is considered to be one of the most destructive pathogen of root rot of summer squash. At present, PGPR products against these two kinds of diseases have become the focus of scholars at home and abroad, so collecting and researching PGPRs have an important significance for biological control.In this study, solubilizing phosphorus, nitrogen fixation and secreting IAA capacity of 19 PGPR strains were tested by dissolving phosphorus circle and colorimetric method, acetylene reduction assay(ARA), colorimetric method of Salkowaki; the antagonistic effects of PGPRs were determinated to Sclerotinia sclerotiorum and Fusarium oxysporum by panel confrontation method, and the controlling broad spectrum of the strains were studied; the biocontrol effect of the excellent antagonistic strains were conducted to sclerotinia rot of colza and root rot of summer squash in greenhouse pot experiment; 11 excellent biocontrol strains were identified by morphological observation, physiological, biochemical and molecular biology methods; the effect of bio-inoculant on the growth of rapeseed and squash were studied. Main results are as follows:1. PGPR strains had different growth promoting propertiesAmong 19 PGPR strains, 14 strains had strong solubilizing phosphorus capacity that were 3.79-204.74 g/m L, 14 strains had nitrogenase activity in the 7.14-246.46 nmol C2H4·h-1m L-1, and 10 strains had the ability to secrete IAA, secreting value were 4.34-54.36 μg/m L.2. Efficient PGPR strains were obtained to antagonize six fungous pathogenAll strains were conducted to antagonize Sclerotinia sclerotiorum, Fusarium oxysporum, Fusarium oxysporum f. sp. cucumerinum, Helminthosporium sativum, Alternaria solani and Rhizoctonia solani by panel confrontation method. The results indicated that strains LHS11 and FX2 showed obvious antibacterial activity to the six fungous pathogen, inhibition rates of strain LHS11 reached 85.71%, 65.98%, 67.38%, 71.03%, 65.34%, 69.53%, and strain FX2 rised up to 82.14%, 66.80%, 69.07%, 78.17%, 70.52%, 73.82%, respectively. Strains LHS11 and FX2 could make the hyphae give rise to different distortion, their sterile fermentation broth caused inhibitory effect to part pathogens. Comprehensive analysis indicated that strains LHS11 and FX2 had better antibacterial spectrum, and could inhibit the growth of pathogens by secondary metabolites, nutrition and space competition, etc.3. The antagonistic PGPRs were Bacillus sp. and Pseudomonas sp.The obtained 11 PGPR strains were identified by morphological observation, physiological and biochemical, 16 S r DNA sequence analysis. The results showed that the strains LHS11 and FX2 were Bacillus subtilis, strains XX2, LM4-3, F1-4 and LX22 were B. pumilus, strain XX6 was B. simplex, strains FX1 and XX1 were B. cereus, and strains XX5 and PGRS-3 were Pseudomonas fluorescens.4. Compound inoculant(LHS11+FX2) had better growth promoting capacity and control effect on rapeseed and zucchini in greenhouseThe panel confrontation test showed that the suppression rate of strains LHS11 and FX2 to Sclerotinia sclerotiorum and Fusarium oxysporum were all more than 80% and 60%, respectively. Oxford cup test showed there was no antagonism between strains LHS11 and FX2, so they were made of different inoculating agent. On rapeseed leaves in vitro and the pot experiment, compound inoculant(LHS11+FX2) had better control effect to sclerotinia rot of rape, the inhibition rates reached 83.75% and 80.51%, respectively. Through the investigation of disease incidence of different treatment on zucchini in greenhouse, we found that compound inoculant(LHS11+FX2) had better control effect that could reach 57.14%. In addition, compared with the control, compound inoculant(LHS11+FX2) could increase the plant height, shoot fresh weight, root fresh weight and root dry weight significantly on rapeseed in greenhouse potting experiment, they were increased by 32.30%, 73.87%, 323.08% and 186.67%, respectively. Compound inoculant(LHS11+FX2) had better growth promoting capacity and control effect than single inoculant.5. 85% chemical fertilizer + compound inoculant showed better growth promoting effect on zucchini in the field trials7 PGPR strains were made of compound inoculant that accorded with the biological fertilizer with “NY227-94” standard. Using compound inoculant to dress seeds conducted the test with chemical fertilizer of different ratios on zucchini in the field trials. Compared with no fertilizer treatment, the results showed that compound inoculant with chemical fertilizer of different ratios could all significantly increase shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, root surface area and root length in full-blossom period and mature period, among all treatments, 85% chemical fertilizer + compound inoculant showed better growth promoting effect, it significantly increased production in mature period, which were increased by 27.13%, it largely saved the fertilizer input costs and improved production efficiency.