Three rhizobacteria differentially change endogenous hormones and yield in four rice cultivars

Four Thai rice cultivars Pathum Thani 1, RD41, RD57, and RD85 were investigated to observe their responses to Plant Growth Promoting Bacteria Bacillus sp. N7 (N7), Lysinibacillus sp. N5 (N5), and Bacillus thuringiensis B20 (B20). A pot experiment with 5 plants pot(-1) and four replicates was used. This study reported that the combination of plant growth promoting bacteria and optimized fertilization play role in crop yield enhancement by modulating endogenous levels of indole-3-acetic acid, salicylic acid, and tryptophan. Endogenous levels of indole-3-acetic acid, salicylic acid, tryptophan, and grain-yield-related components and grain yield of four Thai rice cultivars Pathum Thani 1, RD41, RD57, and RD85 were measured. Significant (p < 0.05) increase in grain yield observed at PTT1, RD41, and RD85 (40.13-51.18 g pot(-1), 43.33-54.05 g pot(-1), 47.80-69.08 g pot(-1), respectively), but no significant (p > 0.05) grain yield increase in RD57 (48.75-51.75 g pot 1) when compared to uninoculated conditions. Significant (p < 0.05) endogenous indole-3-acetic acid, salicylic acid, and tryptophan level changes compared to the uninoculated control were observed across four Thai rice cultivars. Consortia development to enhance the plant growth promoting bacteria capability and larger field trials will be performed in the future to further investigate the efficacy of the bacteria in the real-field application.

Automated summary

The combination of plant growth promoting bacteria and optimized fertilization can enhance crop yield by modulating endogenous hormone levels. Significant increase in grain yield was observed in certain Thai rice cultivars, while there was no significant effect in others.