The role of rhizobacteria in rice plants: Growth and mitigation of toxicity

Abstract

Allelopathic compounds reduce the growth and productivity of upland rice plants, especially in consecutive plantations. The rhizobacteria Pseudomonas fluorescens BRM-32111 and Burkholderia pyrrocinia BRM-32113 have been recorded as growth promoters in rice. This study was developed to understand the effect of the application of rhizobacteria on upland rice plants in consecutive plantations. Experiments were conducted in a completely randomized design with four replications of four treatments: rice seed inoculated with P. fluorescens BRM-32111, rice seed inoculated with B. pyrrocinia BRM-32113 (both sown on soil with rice residue), non-inoculated plants sown on soil with rice residue (control with residue (WR)), and non-inoculated plants on soil with no residue (NR). Roots and seedling growth were adversely affected by allelopathic compounds in control WR plants. Plants inoculated with rhizobacteria P. fluorescens BRM-32111 or B. pyrrocinia BRM-32113 induced an increase of 88% in biomass, 3% in the leaf area, 40% in length, 67% in root biomass, 21% in chlorophyll a, 53% in chlorophyll (a+b), 50% in rate of carbon assimilation (A), 227% in A/rubisco carboxylation efficiency (C i) and 63% in water use efficiency (WUE) compared to control WR plants. These results indicate that rhizobacteria P. fluorescens BRM 32111 and B. pyrrocinia BRM 32113 increase the tolerance of rice plants to stress from allelochemicals. There are possible practical agricultural applications of these results for mitigating the effects of environmental allelochemistry on upland rice.

Bioprospecting plant growth‐promoting rhizobacteria from rice genotypes and their influence on growth under aerobic conditions

“…Several authors have isolated different strains of Pseudomonas sp. from the rice rhizosphere and have reported significant increase in plant height, shoot and root dry weights, chlorophyll content and stress tolerance in Pseudomonas inoculated rice plants under traditional cultivation system compared to the uninoculated rice plants as a result of production of adequate amounts of phytohormones and considerable nitrogen fixation activity [16,45,46].…”

“…[15], Burkholderia sp. [16], Lysinibacillus sp. [17] have been isolated from the rhizosphere of upland rice varieties and have shown to be highly effective in growth promotion under greenhouse and field conditions.…”

Soil bacterial communities interact with silicon fraction transformation and promote rice yield after long-term straw return

“…Soil bacterial community plays a key role in regulating soil processes and its composition determines agricultural soil sustainability (Rêgo et al, 2018). The straw return provides energy and nutrients for soil bacterial growth (Chen et al, 2017) and many studies have shown that straw return redistributes the soil bacterial community composition (Lu et al, 2015;Zhao et al, 2017;Su et al, 2020).…”

Effect of rhizosphere bacteria on antioxidant enzymes and some biochemical characteristics of Medicago sativa L. subjected to herbicide stress

“…Shahid and Khan found that due to inoculating chickpea with Burkholderia cepacia, a phosphate solubilizing and glyphosate-resistant bacterium, the concentrations of chlorophyll b, a, and carotenoid pigments were increased, as well as the negative effects of glyphosate on chickpea were decreased (Shahid and Khan 2018). In Rego and colleagues study, two rhizobacteria, including Pseudomonas fluorescens BRM-32111 and Burkholderia pyrrocinia BRM-32113, were isolated from rice rhizosphere, and their role on mitigation of toxic allelochemicals and crop yield were assessed in field experiment in the presence of allelopathic rice residues (Rêgo et al 2018). They found that rice inoculation ; cadmium, lead and arsenic resistant species, respectively, while applied on rice.…”