Interaction between Rhizobacteria and Andrographis paniculata Under Water Limitation

Drought stress is a major agricultural problem that leads to increased accumulation of ethylene in plants. It also has negative effects on plant productivity and growth. Andrographis paniculate is an important herb widely used in medical applications to inhibit diseases caused by viruses. In order to improve the production quality and growth of the A. paniculata, ACC-deaminase plant growth-promoting rhizobacteria were isolated from rice rhizosphere soil. All bacterial isolates were screened for their plant growth-promoting properties, including ACC deaminase, IAA production, biofilm formation, and exopolysaccharide production. Among the bacterial isolates, Rh-01 and Rh-22 exhibited positive results (cutting-edge) in all tests and were identified as Paenibacillus polymyxa Rh-01 and Stenotrophomonas maltophilia Rh-22, respectively. These strains were selected for further pot experiment study. Our results revealed that treatment with chemical fertilizer showed the highest potential to promote A. paniculata seedlings under normal moisture conditions. However, under water limitation conditions, the application of ACC-deaminase plant growth-promoting rhizobacteria led to a higher chlorophyll content compared to the control treatment. In addition, under normal irrigation conditions, plant growth promoting rhizobacterial increased relative water content and total biomass. In terms of plant stress markers, the proline content in Andrographis paniculate’s seedling stage was low under water limitation conditions. In conclusion, to enhance the growth of A. paniculate seedlings during water limitation stress, a combination of microbial biofertilizers and chemical fertilizers is beneficial.