Bacilli consortia positively regulates agronomic and growth traits in rice

Abstract

In our study, soil samples from the rhizosphere of various uncultivated weeds were collected from fifteen different locations of Gujarat. Heat treatment was given at 65°C for 20 minutes prior to initial screening for spore-forming Bacilli spp. Among them, 20 nitrogen-fixing (NFB), 27 phosphate solubilizing (PSB) and 15 potassium mobilizing (KMB) isolates were screened primarily. After molecular identification only Bacilli isolates were further selected and characterized. Three superior Bacillus isolates were selected from each category by secondary screening. All three isolates for nitrogen fixation were found nif positive, while Bacillus megaterium (NAUN2) showed maximum 2.04 µmol/ml ammonia production followed by Bacillus sp. (NAUN1) and Lysinibacillus macroides (NAUN3) with 0.64 and 0.99 µmol/ml, respectively. Bacillus sp. (NAUP1) gave maximum 401.94 µg/ml phosphate solubilization on Pikovaskya broth media after third day while Bacillus sp. (NAUP2) and Brevibacillus sp. (NAUP3) showed 376.74 and 308.16 µg/ml phosphate solubilization, correspondingly. Lysinibacillus macroides (NAUK2) showed maximum 228.14 µg/ml potassium mobilization on Aleksandrov after the twentieth day while Lysinibacillus macroides (NAUK1), Bacillus megaterium (NAUK3) and Bacillus sp. (NAUP1) had effective 196.91, 158.18, 59.33 µg/ml potassium mobilization, respectively. Interestingly, no selected Bacilli isolates from the consortia were found to have inhibitory effect on other isolates in compatibility test. Out of the nine Bacillus isolates NAUK1, NAUK2, NAUK3 were found to be effective against rice pathogen Magnaportha oryzae on PDA plates. All the nine isolates were checked for IAA and siderophore production. Isolate NAUN1, NAUP3, NAUK1, NAUK2 and NAUK3 showed 37.2%, 17.9%, 33.6%, 38.9%, 48.2% siderophore production on CAS medium after 72 hrs, respectively. Isolate NAUP3 showed maximum 146.68 µg/ml IAA production while NAUN1, NAUN3, NAUP1, NAUK2 and NAUP2 showed 99.37, 99.37, 114.57, 101.46, 93.48 µg/ml IAA production, respectively after the seventh day. Rice seeds were inoculated with individual isolate and different Bacilli consortia, which significantly improved growth parameters as compared to control in pot study after 60 days of sowing. 100% RDF + NPK consortia gave significantly increased root length (11.65%), shoot length (10.28%), no. of leaves (17.39%), leaf area (11.68%) and chlorophyll content in leaf (4.76%). Similar trends were observed when the data was compared with absolute control. The spore forming Bacilli consortia was able to survive a wide range of temperature and pH fluctuations and found effective Nfixers, P-solubilizers, K-mobilizers, siderophore producers, IAA producers with antagonistic activity against rice pathogen Magnaportha oryzae.

Plant Growth-Promoting Activity of Bacillus sp. PG-8 Isolated From Fermented Panchagavya and Its Effect on the Growth of Arachis hypogea

“…Rhizobacteria, Bacillus cereus, and Bacillus megaterium produced 2.3 and 6.2 µmol/ml of ammonia, respectively, after 72 h (Dutta and Thakur, 2017). Bacillus megaterium isolated from soil produced 2.04 µmol/ml ammonia after 96 h (Krunal and Sanjay, 2020). Ammonia accumulation in soil may lead to alkaline conditions that suppress the growth of several plant pathogens.…”

Effects of Bacillus subtilis and Saccharomyces cerevisiae inoculation on soil bacterial community and rice yield under combined irrigation with reclaimed and fresh water

“…PGPB can mitigate the adverse effects of salt stress, which hinders the growth and development of rice plants, through the mediation of phytohormone (ethylene) and reactive oxygen species (ROS) accumulation, maintaining ion homeostasis, improving photosynthetic capacity, and enhancing stress-responsive genes expression [53] . Rice seeds inoculated with individual isolates and different Bacilli consortia showed significantly improved growth parameters [54] . In this study, the dry weight of the root, stem, and leaf, the spike length, the filled grain number, and the weight of plants grown in soil inoculated with B. subtilis and S. cerevisiae were higher than that in CK.…”

“…This is due to B. subtilis inducing the rice root system and improving the absorption of nutrients [62] , as well as accelerating the development of the roots, stems, and leaves (Figure 1 and Table 3). The nutrient consumption in the soil after inoculating with bacilli consortia was high [54] . Thus, inoculation with Bacilli consortia improved the growth parameters of rice [61] , similar to Plant Growth-Promoting Rhizobacteria (Acidovorax delafieldii), which increases the absorption of N, P, and K.…”