ABSTRACT Technologies that use rhizobacteria to promote plant growth are increasing in agriculture, results have shown improvements in soil quality, increases in productivity, and decreases in the use of synthetic inputs, The objective of work was to characterize bacterial isolates regarding their biological activity and growth promotion of soybean plants grown in a controlled environment. Fifteen bacteria were isolated from soils with continuous use of biological fertilizer. They were evaluated for enzymes production (amylase and protease), nitrogen fixation, antagonistic activity to phytopathogenic fungi, and indoleacetic acid (IAA) production, Soybean seeds were inoculated with bacterial isolates in a greenhouse and evaluated for plant development and soil chemical attributes. The results showed that 8 of the 15 isolates presented production of amylase, protease, or both and 4 isolates presented nitrogen-fixing capacity. The percentage of isolates with high or moderate inhibitory action against the fungi Sclerotinia sclerotiorum, Macrophomina phaseolina, and Fusarium solani were 73.3%, 66.6%, and 73.3%, respectively. The IAA production varied from 8.56 to 31.33 µg mL-1 (5 isolates had low, 6 had moderate, and 4 had high production). The soybean development was significantly higher in 80% of the treatments with inoculation with bacterial isolates. Five bacterial isolates effectively present all characteristics for use as inoculant (biofertilizer) to promote the development of soybean plants.

ABSTRACT Alternative management measures have been used to reduce nematode population levels in affected areas. In this perspective, the objective was to evaluate the efficiency of nematicides based on fungus and bacterium, associated with poultry litter applied via ground in the management of Pratylenchus brachyurus and Heterodera glycines in soybean and corn crops in succession. The experiment was conducted in the 2018/19 growing season in the municipality of Ipameri– GO (-17°34’55.58”S−48°12’02.35”O) in naturally infested field, arranged in a randomized block design, with 10 treatments and 4 replicates, being: T1- Witness/ control, T2- Poultry litter, T3- P. lilacinum + T. harzianum, T4- B. subtilis + B. licheniformis, T5- P. chlamydosporia, T6- Abamectina, T7- P. lilacinum + T. harzianum + Poultry litter, T8- B. subtilis + B. licheniformis + Poultry litter, T9- P. chlamydosporia + Poultry litter, T10- Abamectina + Poultry litter. The poultry litter was added in the soil 10 days before planting. The plots were composed of 6 lines of 6 m, with a spacing of 0.5 m. In the soybean crop at 45 and 90 days after sowing (DAS), the fresh weight of the roots (MFR), nematological variables and productivity were evaluated. In corn, only nematological variables were evaluated at 60 DAS. The treatments using P. lilacinum + T. harzianum and B. subtillis + B. licheniformes increased the MFR and reduced the number of P. brachyurus and H. glycines at the root. P. chlamydosporia associated with poultry litter increased in productivity in soybean plants.

ABSTRACT No isolated factor influences soybean development and production more than the sowing date, but the responses of cultivars sown on different sowing dates depends on their sensitivity to environmental conditions. Thus, this study evaluated the adaptability and stability of 17 soybean genotypes in relation to yield, as well as to the grain oil and protein contents as a function of different sowing times. The experiment was designed in randomized blocks with three replications and a 17 × 5 factorial scheme. The genotypes were: Conquista, CD 223 AP, Elite, Garantia, Bioagro lineage, M-Soy 8400, M-soy 8001, Nambu, Sambaíba, Esplendor, UFVS 2006, UFVS 2005, UFVTN 102, UVF 18, UFV 16, Valiosa, Vencedora, and the five sowing dates were: SD1 = 11/3, SD2 = 11/20, SD3 = 12/07, SD4 = 12/23, and SD5 = 01/09. The M-Soy 8001, UFV 18 and Garantia genotypes showed high oil contents, with adaptation to all sowing dates and stability when sown on the most favorable dates. The Bioagro lineage, CD 223 AP, and Garantia genotypes were adapted and stable when sown on all sowing dates and had higher protein contents than the other genotypes, regardless of the sowing date. The Elite, Nambu, and Garantia genotypes were adapted and stable when sown on the most favorable sowing dates and presented high grain yields when sown in early December. The findings indicate that the Garantia genotype is the most suitable for the growing conditions of the central-north region of the state of São Paulo.

ABSTRACT Sourgrass (Digitaria insularis) is one of the main species causing significant losses in Brazilian soybean production systems. Thus, this paper aimed to evaluate sourgrass interference on soybeans grown under Cerrado conditions. Three field experiments were conducted, of which the first two (E1 and E2) simulated sourgrass after pre-sowing burndown, using plants already emerged by the time soybeans were sown; whereas the third (E3) simulated both sourgrass and soybeans emerged simultaneously. Both E1 and E2 were conducted in a randomized complete block design (RCBD) with five treatments based on sourgrass infestation densities (0, 2, 4, 6, and 8 plants m-2) and four replications. In turn, E3 was also carried out in an RCBD but with treatments arranged in a 2 x 5 factorial and four replications. The first factor comprised two soybean cultivars, while the second was sourgrass density levels, just as in E1 and E2. The results showed that increasing sourgrass densities reduced soybean yield regardless of the plant growth stage when the crop was sown. Yield losses were higher when sourgrass plants were already established by the time soybean was sown. Soybean yield losses reached up to 80% under higher sourgrass infestation levels.