Colonization of Potassium-Solubilizing Purple Nonsulfur Bacteria and Their Role in Promoting the Growth of Hybrid Maize

The use of biofertilisers to replace conventional chemical fertilisers has been widely investigated. However, the colonization of microbes in plants and their effects on plant growth are still unclear. The experiment aimed to (i) determine the ability of potassium-solubilizing purple nonsulfur bacteria (Ksol-PNSB) to colonize in hybrid maize and (ii) measure their capacity to promote plant growth. A randomised complete block design experiment was conducted in undeposited alluvial soil collected from An Phu, An Giang, under nethouse conditions with five treatments and six replications. The treatments were: (i) the control, (ii) Cereibacter sphaeroides M-Sl-09, (iii) Rhodopseudomonas thermotolerans M-So-11, (iv) Rhodospeudomonas palustris M-So-14, and (v) a combination of the three strains. Results revealed the presence of bacteria in soft tissues of the cortex and medulla in the root hair region of hybrid maize plants. Supplying one or three strains of Ksol-PNSB increased crop height (20.7–34.4%), root length (17.0–40.5%), root biomass (20.9–154.0%), and stem-leaf biomass (73.8–173.8%) compared to the control. The current study has successfully revealed the inhabitation locations of the beneficial bacteria within plant tissues, along with the improved growth characteristics of the hybrid maize. The current study is a good reference for studies investigating the works of beneficial microbes in plants. However, further molecular investigations should explore the potassium-solubilizing traits of the bacteria.