Study On Functional Biologicals For Rice Endophytic Actinomycete OsiSh-2 And OsiLf-2

The overuse of chemical fertilizers and pesticides has long been a problem in China.Compared with chemical fertilizers and pesticides,biological agents are highly efficient without contamination.The development of new biological products is an important means to ensure food security.In our previous study,we have isolated and screened the rice endophytic Streptomyces hygroscopicus OsiSh-2 with high antagonism to blast fungus and Streptomyces albidoflavus OsiLf-2 with remarkable growth-promotion effect on rice.In this paper,Osish-2 and Osilf-2 were taken as the research objects and a series of studies were carried out on the development of biologicals.The results were obtained as follows:1.The physicochemical properties of the spores of OsiSh-2 and OsiLf-2 were investigated.The results showed that OsiSh-2 spores had good hydrophilicity and could be developed as water-soluble powder.OsiLf-2 spores are hydrophobic and could be developed as rhizosphere immobilized preparation.Meanwhile,OsiSh-2 spores could be kept under high temperature for a long time as it could survive under 55?over one week.However,OsiLf-2does not have high-temperature resistance,so it is necessary to avoid high-temperature stress during production and transportation.In addition,the compatibility of endophytic actinomycetes OsiSh-2 and OsiLf-2 with chemical pesticides commonly used to control rice blast was tested.OsiSh-2 had good biocompatibility with kasugamycin and azoxystrobin.and OsiLf-2 has good biocompatibility with tricyclazole and pyriole.This indicated that OsiSh-2and OsiLf-2 can be mixed with chemical pesticides.2.OsiSh-2 solid fermentation sporulation system was established with agricultural wastes and cheap materials such as straw powder,soybean flour and rice flour.Through a single factor and orthogonal condition optimization test,the optimal conditions for OsiSh-2spores production by solid fermentation were determined as straw powder36.8%,Soybean flour 30.2%,Rice flour 32.9%,cultured temperature 30?,culture time 15 days.Under this condition,the spores reached 3.75?10~9/g.3.OsiLf-2 chitosan-sodium alginate immobilize microspheres and OsiLf-2 rice seed coating were prepared.Both of these preparations could be preserved at normal temperature for 300 days,the OsiLf-2 spores inside were still active,and could grow and reproduce under appropriate conditions.After 15 days of cultivation,plant height,fresh weight and dry weight of above ground of OsiLf-2 rice seed coating were significantly higher than those of the control group by 12.4%,30.4%and 26.3%respectively.To sum up,in this paper,the author conducted a preliminary exploration of the biocontrol preparation of rice endophytic actinomycetes OsiSh-2 and OsiLf-2,which laid a foundation for the application of the two actinomycetes strains on agriculture.