Response of common bean to Rhizobium reinoculation in topdressing

ABSTRACT The response capacity of the bean to fix atmospheric nitrogen is questionable, mainly due to its inability to supply all the nitrogen in the flowering and grain filling phases when the crop needs it most. Thus, a new application of inoculant can keep the population of rhizobia in the soil at adequate levels, meeting all the nitrogen demands of the plant. This study aimed to investigate the nodulation capacity and the production of beans submitted to doses and reinoculation of Rhizobium in topdressing under field conditions in two growth stages. For this, an experiment was conducted using a randomized block design with four replicates in a 4 × 2 + 2 factorial scheme. The treatments consisted of the application of four doses of liquid inoculant containing Rhizobium tropici (SEMIA 4088), in the concentration 2 × 109 CFU g-1, in topdressing (0, 100, 200 and 400 mL ha-1), in two development stages (V4 and R5) of plants, and two additional treatments (inoculation via seed at a dose of 100 g of the product per 50 kg of seeds and mineral nitrogen fertilization at a dose of 16 kg ha-1 applied at sowing and 60 kg ha-1 in topdressing, divided into two stages, with half being applied at the stage V3 and the other half in V4 stage).The inoculant application increased the nodulation rates of bean cultivar BRS Cometa and the dry biomass produced by plants, using doses of 232 and 221 mL ha-1, respectively. The dose of 257mL ha-1 of the liquid inoculant applied in topdressing at the V4 stage, and the inoculation via seed provide greater common bean yield without supplementing mineral nitrogen.

Mycorrhizal fungi Glomus spp. propagation in zeolite enriched with mycorrhiza helper bacteria for controlling nematode in coffee

Arbuscular mycorrhizal fungi (AMF) play a role in suppressing the nematode Pratylenchus coffeae. Mycorrhizal helper bacteria (MHB) can increase the effectiveness of AMF to control the diseases. The experimental purpose was to increase the spore population of AMF Glomus spp. in zeolite-based formulation inoculated with liquid consortia of Pseudomonas diminuta and Bacillus subtilis as MHB. The experimental design was a completely random design with six treatments consisted of 106, 107, 108, and 109 CFU/mL MHB liquid inoculants. The control treatments were water and 2% molasses. All treatments were replicated four times. A total of 300 mL/pot Liquid inoculant of MHB have been inoculated a three day before transplanting the maize seedling to the Zeolite inoculated with Glomus spp. in the pot. One month after MHB inoculation, Glomus formulation in Zeolite with different levels of MHB increased the degree of infection. Three months after MHB inoculation, spore content in Zeolite increased. The density of P. diminuta and B. subtilis in zeolite-based mycorrhizal inoculant increased at the end of the experiment. Liquid inoculant MHB contained 108 CFU/mL enhanced spora number fourth times compared to the control. This experiment suggests that P. diminuta and B. subtilis were effective to increase the spore density of AMF inoculant.

Polyvinylpyrrolidone (PVP) and Na-Alginate Addition Enhances the Survival and Agronomic Performances of a Liquid Inoculant of Bradyrhizobium japonicum for Soybean (Glycine max (L.) Merr.)

Nontoxic polymers PVP and Na-alginate may provide a favorable environment for the survival of bacteria. Therefore, PVP and Na-alginate were added to a growth medium to develop a liquid inoculant of Bradyrhizobium japonicum strain. The strain was identified by 16S rDNA sequencing. The addition of PVP (1.8%) and Na-alginate (0.2%) in the medium promoted a better survival (1.93 × 109 cells mL−1) of B. japonicum strain compared to the control (3.50 × 102 cells mL−1) after 6 months of storage. The combination of PVP and Na-alginate ensured 1.53 × 107 cells mL−1 up to 12 months of storage under ambient temperature (28 ± 2 °C), whereas PVP (1.8%) or Na-alginate (0.2%) alone produced similar cell counts only up to 8 months and 6 months, respectively. Consecutive field experiments proved the efficacy of the liquid inoculant on nodulation and yield of soybean. The combination of PVP and Na-alginate-based inoculation of B. japonicum strain significantly increased the nodule number per plant, number of pods per plant, number of seeds per pod, seed yield, and yield per hectare (p ≤ 0.05). Thus, the combination of PVP- and Na-alginate-based inoculation of B. japonicum has great potential to popularize the organic cultivation of soybean.

Use of inoculants and nitrogen fertilization related to yield and quality of soybean grains

Nitrogen (N) is the essential nutrient for soybean crop, which can be supplied to the crop through bacteria of the genus Bradyrhizobium, present in inoculants. Globally, soybeans are the main product for the production of oils and animal feed, thus the quality of the grains produced is extremely important. Thus, the objective of this study was to determine: yield and physical and physiological properties of grains, depending on the use of different types of inoculants and nitrogen fertilization, in transgenic and conventional soybean. We used a randomized block design with two cultivars, four replications and four treatments: peat inoculant, liquid inoculant, N fertilization and no inoculant, and nitrogenous fertilizer. The results show that the inoculation of soybean with liquid and peaty inoculants resulted in an increase in grain yield. In productivity, the conventional cultivar surpassed the transgenic cultivar. For conventional soybean, the peat inoculant proved to be efficient, since a larger mass of 1,000 grains and greater real specific mass were observed. The liquid inoculant showed high values when evaluated in the transgenic soybean, because it obtained higher values for apparent and real specific masses, number of grains germinated in the germination test and in the accelerated aging test.

Complementary Application of Inoculant in Post-emergence on Soybean Crop

Objective: Inoculation is an important agricultural practice in soybean cultivation that guarantees high productivity without the external input of nitrogen. The objective of this study was to evaluate if the complementary of liquid inoculant (Bradyrhizobium japonicum), via leaf, in different times and different application rates, affects the nodulation, plant growth and soybean productivity. Study design: A randomized complete block design (RCBD) was used, with four replications, in a 5x3 factorial scheme, evaluating the complementary inoculant application, via foliar (0; 75; 150; 225 e 300 mL ha-1), in three stages of vegetative development of the crop (V2, V4 e V6). Location and duration of the study: The study was performed in a commercial area, in the municipality of Sinop, in the northern of Mato Grosso State, between October 2017 and February 2018. Methodology: The cultivation was in soil classified as Red-yellow Latosol with of clayey texture, was in a direct seeding system, using the cultivar NS7901RR. The seeds used were treated and inoculated at sowing, with turfous inoculant and liquid. The experimental units received the complementary applications of inoculant, via pulverization, at 15, 21 and 28 days after emergence, according to the treatment. Results: It was verify that the different times of application of foliar inoculant, does not condition significant differences to the parameters measured in this study. The complementary inoculant application affected, significantly, the leaf chlorophyll index (P <0.05), as well as the dry matter mass of the plants (P <0.001). Up to 300 mL ha-1, a gradual increase in grain yield was verified. Conclusion: The complementary supply of liquid inoculant (B. japonicum), via foliar, in different rates application, affects the nodulation and development of the plants and the productive yield of the crop.

Viability of liquid medium-inoculation of Rhizobium etli in planting furrows with common bean

The objective of this work was to evaluate the viability of liquid medium inoculation of Rhizobium etli in the planting furrow and to certify the efficiency of its strain UFLA 02-100 as a potential inoculant for common bean (Phaseolus vulgaris). The treatments consisted of three application rates of liquid inoculant applied in the planting furrows or in common bean seed, besides two controls without inoculation. The inoculant contained 109 cells of Rhizobium etli mL-1. Regardless of the application method, the yield obtained with the inoculation was equivalent to that of N from urea; however, the application in the furrows, at 0.6 L ha-1, is more advantageous due to the operational practicality and reduced costs.