Pulses provide distinct health benefits due to their low fat content and high protein and fiber contents. Their grain production reaches approximately 93,210 × 10³ tons per year. Pulses benefit from the symbiosis with atmospheric N₂-fixing bacteria, which increases productivity and reduces the need for N fertilizers, thus contributing to mitigation of environmental impact mitigation. Additionally, the root region harbors a rich microbial community with multiple traits related to plant growth promotion, such as nutrient increase and tolerance enhancement to abiotic or biotic stresses. We reviewed the eight most common pulses accounting for almost 90% of world production: common beans, chickpeas, peas, cowpeas, mung beans, lentils, broad beans, and pigeon peas. We focused on updated information considering both single-rhizobial inoculation and co-inoculation with plant growth-promoting rhizobacteria. We found approximately 80 microbial taxa with PGPR traits, mainly Bacillus sp., B. subtilis, Pseudomonas sp., P. fluorescens, and arbuscular mycorrhizal fungi, and that contributed to improve plant growth and yield under different conditions. In addition, new data on root, nodule, rhizosphere, and seed microbiomes point to strategies that can be used to design new generations of biofertilizers, highlighting the importance of microorganisms for productive pulse systems.

Bacterial inoculation stimulates growth and adaptation in micropropagated plants. This study evaluated the effects of biotization on in vitro seedling production and in vivo adaptation in two potato cultivars, Agatha and Duvira. Nine bacterial strains were tested for hormone production and ACC deaminase activity and then inoculated in vitro and re-inoculated in vivo. Growth, adaptation, and tuber production were assessed. Biotization significantly enhanced seedling growth, survival, and tuber yield. Biotized seedlings had a 1.3-fold higher survival rate than the controls. Azospirillum brasilense Ab-V5 and Rhizobium tropici CIAT 899 promoted at least one growth variable in both cultivars under in vitro and in vivo conditions. A. brasilense Ab-V5 consistently improved plant performance across production stages, with re-inoculated plants showing 1.2–1.3-fold increases in stem and root length and a 1.1-fold gain in total dry biomass. Additionally, inoculated plants produced 1.9 times more tubers than the controls. Biotization effects were strain-dependent, with A. brasilense Ab-V5 improving in vitro seedling quality and enhancing plant performance and survivability in vivo.

Las rizobacterias forman parte de la gran cantidad de microorganismos que actúan como agentes de biocontrol, produciendo metabolitos que inducen resistencia sistémica en las plantas que inhiben el crecimiento de patógenos. El objetivo de esta investigación fue evaluar la capacidad de diez rizobacterias de los géneros Rhizobium, Bradyrhizobium, Sinorhizobium, Ochrobactrum y Pseudomonas para producir ácido cianhídrico (HCN), sideróforos y ácido indol-acético (AIA), disolver fosfato, fijar nitrógeno e inhibir el crecimiento de fitopatógenos. Se realizaron todas las pruebas fisiológicas y bioquímicas correspondientes, así como la prueba de antagonismo in vitro contra los fitopatógenos Fusarium oxysporum, Colletotrichum gloeosporioides y Rhizoctonia solani. Cinco cepas produjeron una mayor cantidad de AIA en relación a las otras en presencia de triptófano, la cepa ES1 (Ochrobactrum sp.) produjo HCN, el 50 % de las cepas evaluadas liberaron sideróforos, el 60 % disolvió fósforo, y todas resultaron positivas para la fijación de nitrógeno. Nueve cepas inhibieron el crecimiento de F. oxysporum entre 40 % y 65 %, la cepa Alf (Pseudomonas fluorescens) inhibió además el crecimiento de C. gloeosporioides en un 22 %, y ninguna inhibió el crecimiento de R. solani. Los rizobios evaluados y la cepa de Pseudomonas fluorescens podrían ejercer efectos beneficiosos sobre las plantas a través de mecanismos directos e indirectos, o una combinación de ambos, lo que las convierte en una opción sostenible para la producción de cultivos.

Caracterización fenotípica y genotípica de doce rizobios aislados de diversas regiones geográficas de Venezuela

The practice of producing more vigorous seedlings represents a competitive advantage at the time of transplanting a crop, and the use of combined biofertilizers are a sustainable ecological alternative. The objective of this research was to select a microbial consortium for the production of F1 2000 hybrid onion seedbeds under shade-house conditions. Five rhizobacterial strains of the genera Rhizobium (ME01 strain), Bradyrhizobium (Leu2A and YE1 strains), Ochrobactrum (ES1 strain) and Pseudomonas (Alf strain), which have shown favorable effects on pepper and lettuce seedlings. These rhizobacteria were inoculated in a mixed manner (microbial consortium) in onion as follows: Alf+ES1, ME01+ES1, ES1+Leu2A, Alf+Leu2A, YE1+ES1, ME01+Alf, YE1+Alf, ME01+YE1, YE1+Leu2A, ME01+Leu2A, using a soil from San Juan de Lagunillas-Mérida, Venezuela under shade-house conditions for 60 days. The following variables were determined: number of leaves, pseudostem base diameter, aerial and root length, aerial and root fresh and dry weight. Additionally, a CO2 assimilation curve under different light levels was carried out on the seedlings of the selected consortium to observe their photosynthetic response. The consortium ME01 + Leu2A (Rhizobium tropici + Bradyrhizobium japonicum) increased all studied variables, especially the pseudostem base diameter, essential for onion cultivation, and yielded higher seedlings CO2 assimilation rates. The use of this microbial consortium is recommended as an option for agricultural production under seedbed conditions.

Arbuscular mycorrhizal fungi are important components of the soil microbiota which interact with other beneficial microorganisms in the rhizosphere. The synergistic effect of this naturally occurring association between the soil and introduced microorganisms to improve growth and to cope with biotic and abiotic stresses plays a key role in crop productivity. In this research, the native mycorrhizal colonization of onion (Allium cepa L.) was evaluated in the presence of a plant growth promoting microbial consortium (MC), under inorganic fertilization and water deficit regimes, in a semiarid region of the Venezuelan Andes. The main objectives were to determine the colonization potential of arbuscular mycorrhizae and to quantify the presence of mycorrhizal spores in soil under field conditions. An onion crop was established with normal irrigation (NIr) (100% ETc) and water deficit (WD) (67% ETc), with different fertilization treatments (MC with 0%, 50%, and 100% NPK). Native mycorrhizal colonization was determined by counting vesicles and arbuscules in the roots of onion plants in all treatments, and mycorrhizal spores in the soil of the experimental plot were quantified before and after the trial in the rhizospheric soil for each treatment. The treatments showed no significant differences in native mycorrhizal colonization, but the soil spore count was higher in the MC 100% NPK NIr treatment. Additionally, the mechanization of the plot significantly reduced the presence of mycorrhizae in the soil, suggesting that greater implementation of non-conventional practices could improve preservation of biodiversity and increase soil health through agricultural management.