Plant growth-promoting bacteria as inoculants in agricultural soils

Abstract

Plant-microbe interactions in the rhizosphere are the determinants of plant health, productivity and soil fertility. Plant growth-promoting bacteria (PGPB) are bacteria that can enhance plant growth and protect plants from disease and abiotic stresses through a wide variety of mechanisms; those that establish close associations with plants, such as the endophytes, could be more successful in plant growth promotion. Several important bacterial characteristics, such as biological nitrogen fixation, phosphate solubilization, ACC deaminase activity, and production of siderophores and phytohormones, can be assessed as plant growth promotion (PGP) traits. Bacterial inoculants can contribute to increase agronomic efficiency by reducing production costs and environmental pollution, once the use of chemical fertilizers can be reduced or eliminated if the inoculants are efficient. For bacterial inoculants to obtain success in improving plant growth and productivity, several processes involved can influence the efficiency of inoculation, as for example the exudation by plant roots, the bacterial colonization in the roots, and soil health. This review presents an overview of the importance of soil-plant-microbe interactions to the development of efficient inoculants, once PGPB are extensively studied microorganisms, representing a very diverse group of easily accessible beneficial bacteria.

The Role of Soil Beneficial Bacteria in Wheat Production: A Review

“…Due to high cost of chemical fertilizers and negative environmental effects, the use of PGPR as biofertilizer is advantageous for development of sustainable agriculture, increasing agronomic efficiency, once the use of chemical fertilizers can be reduced or eliminated if the inoculants are efficient [6]. The use of bio-fertilizers with a good management can decrease the leaching loss of nitrate and phosphate from the agricultural land and improve the ground water quality [190].…”

“…The practice of PGPRs is promising in reducing the use of chemical fertilisers, at the same time maintaining yields at commercially viable levels and/or maintaining grain protein content [3]. As such, PGPR contributes to the improvement of both local and global environments, reducing dependence on non-renewable resources while still being economically competitive (both price and quality aspect) [4][5][6].…”

Influence of plant growth-promoting rhizobacteria (PGPR) on blackberry (Rubus glaucus Benth. cv. thornless) growth under semi-cover and field conditions

“…Genera such as Azospirillum, Azotobacter, Burkholderia, Enterobacter, Klebsiella, Pseudomonas and Bacillus are some of the most prominent Plant Growth-Promoting Rhizobacteria (PGPR). Within the mechanisms of action of these bacteria are as follows: the synthesis of hormones such as indoleacetic acid (IAA) and reduction of ethylene, solubilization of phosphorus, nitrogen fixation, decreased toxicity of heavy metals, and biocontrol of plant diseases (Souza, Ambrosini & Passaglia, 2015). Sustainability in agriculture involves maintaining high productivity through environmentally acceptable practices.…”

Promoting fruit seedling growth by encapsulated microorganisms

“…Another interesting observation is that isolates that promoted the growth of sugar apple seedlings came from graviola, evidencing that isolates from one host can easily colonize hosts of different species, even with greater intensity (Silva et al, 2006). These characteristics may be associated to the efficiency of root colonization by microorganisms, since the exudation of different compounds attracts different microbial populations (SOUZA et al, 2015). Means followed by the same letter in the column do not differ by the Tukey test, * significant at 5% probability, ** significant at 1% probability and ns not significant.…”