Abstract
ABSTRACT For decades, researchers around the world search for strategies aiming at higher sustainability in agriculture. The microbial inoculants or biofertilizers are biotechnological products used for different purposes, the main one being to totally or partially replace chemical fertilizers, with an emphasis on N-fertilizers, reducing costs of production and decreasing the contamination of the soil, water, and atmosphere. Depending on the microorganism and the inoculated crop, inoculants can also induce plant protection to abiotic and biotic stresses and positively modify their physiology. Although inoculation studies and the use of inoculants by farmers date more than a century ago, they have gained more notoriety in the past decade. Brazil has a long tradition in the use of rhizobial inoculants, especially for the soybean crop, but it was only in 2009 that the first commercial inoculant carrying the plant-growth-promoting Azospirillum brasilense strains Ab-V5 (=CNPSo 2083) and Ab-V6 (=CNPSo 2084), identified by our research group, reached the market. One decade after the release of these two strains, 10.5 million doses were commercialized for grasses, including corn, wheat, rice, and pastures of brachiarias, and co-inoculation of legumes, such as soybean and common bean. Several research groups in Brazil presented impressive results of increases in root growth, biomass production, grain yield, uptake of nutrients and water, and increased tolerance to abiotic stresses due to the inoculation with Ab-V5 and Ab-V6. In this review, we gathered the results obtained so far in one decade with these two strains in several grasses and legume crops, confirming their versatility and indicating that with convincing, reliable, and consistent results, the Brazilian farmers are receptive to the adoption of new sustainable technologies based on microorganisms.
Highlights
The biggest challenge for the agricultural sector is probably the capacity to produce food on a large scale to supply the increasing global demand
As a sustainable alternative to N-fertilizers, the use of microbial inoculants or biofertilizers increased, products containing live microorganisms named as diazotrophs, with the ability to establish different types of association with plants, providing N from the biological nitrogen fixation (BNF) process (Ormeño-Orrillo et al, 2013; De Bruijn, 2015; Kaschuk and Hungria, 2017)
In eight field trials in which N-fertilizer was applied at a low rate only at sowing, strains Ab-V5 and Ab-V6 contributed to average increases in yield of 27 % for corn and 31 % for wheat, when compared to the non-inoculated control (Hungria et al, 2010)
Summary
The biggest challenge for the agricultural sector is probably the capacity to produce food on a large scale to supply the increasing global demand. In eight field trials in which N-fertilizer was applied at a low rate only at sowing, strains Ab-V5 and Ab-V6 contributed to average increases in yield of 27 % for corn and 31 % for wheat, when compared to the non-inoculated control (Hungria et al, 2010). The number of commercial inoculants carrying A. brasilense increases every year in Brazil, and efforts have been made to publish a list of registered products (Bioinsumos, 2020) This indicates that the farmers are anxious to use new technologies with economic benefits, resulting in grain yield increases and often in a reduction of chemical fertilizers. Fertilization (N) 40 kg ha-1 50 kg ha-1 50 kg ha-1 25 kg ha-1 40 kg ha-1 20 kg ha-1 kg ha-1 mg dm-3 100 mg dm-3 kg ha-1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
