Suitable materials for Paenibacillus sp. BSR₁-₁ immobilization and crop growth stimulation under low water condition

Agricultural challenges due to a water shortage are factors limiting plant growth and productivity worldwide. One way to improve plant growth under unsuitable conditions is to use plant growth-promoting bacteria (PGPB). The objective of this study was to investigate the ability of PGPB to increase peanut, rice, and sweet corn growth under low water conditions. Suitable agricultural materials were selected first to be used in Paenibacillus sp. BSR₁-₁ immobilization. The materials were water hyacinth, reed, and coconut husk. Water hyacinth maintained the bacterial cell number when kept at either -4, 4, or 27-30 °C for both storage times, and water hyacinth soaked with a bacterial cell suspension prepared in 0.5 % ammonium sulfate ((NH₄)₂SO₄) + 1 % glucose was the most suitable method to immobilize the bacterial cells. Paenibacillus sp. BSR₁-₁ with indole-3-acetic acid (IAA) and exopolysaccharide-producing abilities significantly increased root growth of peanuts under the low water condition. Root length and dry weight of inoculated peanut grown under low water conditions were 138.91 % and 156.51 % higher than uninoculated peanut, respectively. This bacterial isolate significantly increased rice shoot dry weight and root length under low and full water conditions. However, it only increased shoot length and root dry weight under the full water condition. Paenibacillus sp. BSR₁-₁ increased the dry weight of sweet corn under both conditions but only increased the root length of sweet corn under the full water condition. The shoot dry weight of inoculated sweet corn under the low water condition was 170.59 % higher than that of the un-inoculated sweet corn. When rice received Paenibacillus sp. BSR₁-₁ under the full water condition, and when peanuts received these bacteria under both conditions, they could produce more tillers and pods than the un-inoculated plants. Thus, Paenibacillus sp.BSR₁-₁ was an appropriate strain to use as a biofertilizer for agricultural proposes in water-limited areas.