Screening and identification of rice growth-promoting strains and their effects on rice growth

Abstract:

[Background] Microorganisms have great potential in promoting rice growth. It is one of the effective ways for reducing the application rate of chemical fertilizers and ensuring safe and efficient rice production to apply rice growth-promoting microorganisms. [Objective] To screen rice growth-promoting microorganisms for the preparation of microbial fertilizers for rice production. [Methods] Strains with high efficiency in fixing nitrogen, solubilizing phosphate and potassium, or producing siderophore and indole acetic acid (IAA) were screened from rice rhizosphere and identified and their effects on seed germination and plant growth of rice were analyzed. [Results] A total of 6 strains (C7-1, L26, C10-19, S11-11, GYM_bt5 and 20-10) with high efficiency in fixing nitrogen, solubilizing organic and inorganic phosphate or potassium, or producing siderophores and IAA, were screened out from the 394 bacterial strains in rice rhizosphere, which were identified as Serratia nematodiphila, Bacillus aryabhattai, Acinetobacter bereziniae, Pseudomonasmonteilii, and Bacillus velezensisbytheir 16S rRNA gene sequences, respectively. The strains, except C10-19, all can significantly promote the seed germination and root development of ‘Jingliangyouhuazhan’. With the help of the 5 strains, the seed germination rate was 25%−43% higher and the root length (14th day of seedling culture) was 18%−42% larger than that of the control, respectively. Particularly, strain C7-1 with the highest level of solubilizing organic phosphate, had the most significant effect on root length, followed by strain 20-10, while strain S11-11 had the most significant effect on the growth and tillering of stems. [Conclusion]StainsC7-1,20-10 andS11-11 significantly promotes rice growth, which can be used for the preparation of rice microbial fertilizers.