Maintaining Growth of Aquatic Morning Glory under Drought Condition by Paenibacillus sp. BSR1-1

Paenibacillus sp. BSR1-1 is a plant growth-promoting bacteria with the ability to produce indole-3-acetic acid, exopolysaccharide and ammonia. This bacterial isolate grew well under low water potential, with the concentration of polyethylene glycol (PEG) ranging from 20 - 30 % (w/v). Paenibacillus sp. BSR1-1 was a suitable bio-inoculant to maintain the growth of aquatic morning glory cultivated under drought conditions in this study. Inoculation of Paenibacillus sp. BSR1-1, as immobilized cells in coconut husk, sawdust or rice straw, tended to stimulate root growth of aquatic morning glory cultivated under drought conditions. The specific root lengths of aquatic morning glory grown under drought conditions were 1.31, 2.86, and 1.76 m/g in the presence of Paenibacillus sp. BSR1-1 immobilized in coconut husk, sawdust or rice straw, respectively. Root length and root dry weight of aquatic morning glory planted under drought conditions in the presence of Paenibacillus sp. BSR1-1 were around 17.71 - 18.08 cm and 0.16 - 0.28 g, respectively. Meanwhile, the root length and root dry weight of aquatic morning glory planted under drought conditions in the absence of Paenibacillus sp. BSR1-1 were only 10.62 - 13.54 cm and 0.04 - 0.11 g, respectively. In addition, the root morphology of aquatic morning glory planted under drought conditions in the presence of Paenibacillus sp. BSR1-1 was more branched and longer than that without Paenibacillus sp. BSR1-1 inoculation. However, the inoculation of Paenibacillus sp. BSR1-1 to soil did not stimulate shoot growth of aquatic morning glory planted under both normal and drought conditions.   HIGHLIGHTS Paenibacillus BSR1-1 is a plant growth-promoting bacteria with the ability to produce indole-3-acetic acid (IAA), exopolysaccharides and enables growth at a low water potential Application of Paenibacillus BSR1-1 as a bio-inoculant tended to maintain the growth of aquatic morning glory under drought conditions The root morphology of aquatic morning glory planted under drought conditions in the presence of Paenibacillus BSR1-1 was more branched and longer than that without bacterial inoculation GRAPHICAL ABSTRACT