Isolation And Identification Of Biocontrol Microbes Against Maize Head Smut And Its Effect On Growth Promotion Of Maize

The purpose of this study is to screen endophytic biocontrol which have biocontrol effect on Maize Head Smut from the healthy maize plants,and to study the identification of mycrobes,optimization of fermentation conditions and promotion of growth,so as to lay a theoretical foundation for biological control of maize head smut.The main results are as follows:1.Based on the factors affecting the germination of teliospores of Sphacelotheca reiliana,the method of germination of teliospores suitable for screening biocontrol bacteria of Maize Head Smut was determined in this study.The teliospores were treated with 0.05 mol/L hydrochloric acid for 12 hours.Maltose was used as the C source in the culture medium,the temperature was 28?,the initial p H value was 7,and the final germination rate of teliospores was 53.14%.2.83 endophytic mycrobes were isolated from different tissues of healthy maize stalks by tissue suspension dilution method.Three endophytic mycrobes were screened out by teliospore germination test.They were endophytic actinomycetes HA-02,HA-05 and endophytic fungi HF-22.Among them,HA-05 strain had the highest inhibition rate,was 89.50%.HA-02 strain was initially identified as Streptomyces flavogriseus and HA-05 strain as Nocardiopsis dassonvillei by morphological,cultural,physiological and biochemical characteristics and molecular biological identification.HF-22 strain was initially identified as Sarocladium implicatum by morphological and molecular biological identification.3.The optimum carbon source for fermentation broth of HA-05 strain was soluble starch and potassium nitrate by single factor test.The optimum fermentation conditions were determined by orthogonal test.The optimum fermentation conditions were p H 7,fermentation time 7 days,liquid loading 50 m L/250 m L,inoculation volume 10%,rotating speed 180 r/min.4.The effects of HA-02,HA-05 and HF-22 fermentation broth at different concentrations on Maize Seed Germination and root bud growth were determined by seed soaking method.The results showed that HA-02 strain had no promoting effect on maize seed germination,but had promoting effect on Radicle germ,among which 75-fold and 100-fold fermentation broth treatment was the most significant.HA-05 strain had obvious stimulating effects on Maize Seed Germination and radicle germ,and the fermentation broth with 20 times concentration was the most significant.HF-22 strain also had obvious stimulating effects on Maize Seed Germination and radicle germ.The 50-fold concentration of fermentation broth was the most significant for maize seed germination,and the 20-fold concentration of fermentation broth was the most significant for the growth of radicle germ.