Short-term Soybean Research Articles

Short-term lime application impacts microbial community composition and potential function in an acid black soil

Soil acidification is a natural process that can be accelerated by intensive nitrogen fertilization. Lime application is a typical agricultural practice to enhance soil pH and increase nutrient availability for crop production. Our study aims to reveal how liming altered soil microbial community composition and potential function in the bulk and rhizosphere soils of soybean growing in an acid black soil. A short-term soybean pot experiment was conducted in an acid black soil with the amendment of five different dosages of lime. Soybean plants were harvested and soil samples were collected at the initial flowering stage. Plant biomass, shoot height and root length, as well as soil chemical properties and total microbial activities of bulk soils were measured. The abundance and composition of microbial communities in bulk and rhizosphere soils were determined using qPCR and Illumina MiSeq sequencing, respectively. Liming significantly increased soybean growth and soil microbial activities, and altered soil properties such as soil pH, available phosphorus (AP), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3−-N). Lime addition increased soil bacterial abundance and decreased fungal abundance in the bulk soils, but had no effect on microbial abundance in the rhizosphere soils as well as alpha-diversity of soil microbial community. Microbial community structures in bulk and rhizosphere soils were significantly varied with lime amendment that were related to soil chemical properties, of which soil pH was detected as the most important soil factors. In addition, liming significantly increased the potential functions of amino acid, cofactors and vitamins mechanisms of bacterial communities and the guild abundance of AM fungi. Lime application altered soil properties, increased soil microbial activities, and changed soil microbial compositions and potential functions, which eventually resulted in the improvement of soybean plant growth.

Short-term soybean intake and its effect on steroid sex hormones and cognitive abilities

To observe the effects of short-term soybean consumption on cognitive spatial abilities and changes in sex endocrine net in both genders. Short-term prospective intervention study. Academic medical center. Fifty-four healthy females and 32 healthy males (18 - 25 y of age). Volunteers were asked to eat 2 g/kg per day of soybeans during 1 week. Saliva and plasma samples were taken, and psychometric tests were performed on the 1st (before soybean intake), 7th (after soybean intake), and 14th days (after washout period) of the study. Salivary T and plasma E(2) were measured. Mental rotation (MR) and spatial visualization (SV) tests were performed on the days of sampling. Soybean intake did not change salivary T and plasma E(2) levels in men. During the washout period, both parameters have shown a tendency to rise. The effect of soybean intake on hormonal parameters in men was, however, dependent on the basal T levels. In women, salivary T as well as plasma E(2) levels showed a tendency toward a decline after soybean intake (the decrease in E(2) was statistically significant) and to increase back toward basal levels during the washout period. Both males and females statistically significantly improved in MR and SV after soybean intake. During the washout period, both genders further improved their results in MR but not in SV. Short-term soybean consumption alters the concentrations of salivary T and plasma E(2) in both men and women. Spatial abilities appear to be improved by short-term soybean intake, but the exact mechanisms require further study.

Soybean response to nodulation by bradyrhizobia differing in rhizobitoxine phenotype

Rhizobitoxine-producing (RT+) strains of Bradyrhizobium japonicum, differing in their abilities to induce foliar chlorosis with ‘Forrest’ soybean (Glycine max [L.] Merr.), were evaluated for effects on short term shoot productivity, nodulation, N2 fixation, and nodule protein production under greenhouse conditions. Soybeans were singly inoculated with washed suspensions of (Group II) USDA strains 31, 46, 76, 94, 110, 123 or 130. Strains USDA 110 and USDA 123 (Group I/Ia) were included as RT-controls. The plants were cultured in the absence of combined N in horticultural-grade vermiculite for 49 days. Beginning 21 days after planting, plants were evaluated weekly for chlorophyll, leaf protein and biomass accumulation, nodular contents of leghemoglobin, soluble protein and RT, and total shoot N content. Rhizobitoxine was detected in nodules of all RT+ strains with the exception of USDA 31. However, only USDA 76 and USDA 94 produced both quantifiable concentrations of RT and symptoms of RT-induced chlorosis. Coincident with moderate to severe chlorosis were reductions in chlorophyll concentrations, shoot and nodule dry weight, leaf protein and total N2 fixation. During extended periods of severe chlorosis, reductions in Lb and soluble nodular protein were observed. Based on carbon accumulation, all non-chlorotic treatments were statistically more productive than the chlorotic treatments. Similarly, non-chlorotic Group II treatments tended to fix less carbon relative to the RT-Group I/Ia controls, although these differences were not statistically significant. The results of this study suggest that, in the absence of discernable foliar chlorosis, the effect of RT+ (Group II) nodulation on short term soybean productivity is minimal.