Weed coexistence in carioca bean inoculated

The supply of nitrogen (N) to the carioca bean plant via inoculation with Rhizobium tropici can prevent competition with the weed community by allowing the crop to absorb the nutrient available in the soil. On this basis, this study proposes to examine the period before weed interference (PBI) in the carioca bean plant following inoculation with R. tropici or N topdressing. The experiments were carried out under field conditions during the summer seasons of 2014 and 2015. A randomized-block experimental design with four replicates was adopted, in a 2 × 11 factorial arrangement (common bean plant inoculated or topdressed with N × 11 periods of coexistence with weeds, namely, 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, or 90 days after emergence [DAE]). Nitrogen topdressing increased the crop's tolerance to coexist with weeds from 6 to 14 DAE, compared with inoculation with R. tropici The PBI for the inoculated common bean plant was 24 and 16 DAE in the years 2014 and 2015, respectively. For the N-topdressed plant, the PBI was 30 DAE in both years.

Enhanced Soybean Productivity by Inoculation With Indigenous Bradyrhizobium Strains in Agroecological Conditions of Northeast Germany

Commercial inoculants are often used to inoculate field-grown soybean in Europe. However, nodulation efficiencies in these areas are often low. To enhance biological nitrogen (N) fixation and increase domestic legume production, indigenous strains that are adapted to local conditions could be used to develop more effective inoculants. The objective of this study was to assess the ability of locally isolated Bradyrhizobium strains to enhance soybean productivity in different growing conditions of Northeast Germany. Three indigenous Bradyrhizobium isolates (GMF14, GMM36, and GEM96) were tested in combination with different soybean cultivars of different maturity groups and quality characteristics in one field trial and two greenhouse studies. The results showed a highly significant strain × cultivar interactions on nodulation response. Independent of the Bradyrhizobium strain, inoculated plants in the greenhouse showed higher nodulation, which corresponded with an increased N uptake than that in field conditions. There were significantly higher nodule numbers and nodule dry weights following GMF14 and GMM36 inoculation in well-watered soil, but only minor differences under drought conditions. Inoculation of the soybean cultivar Merlin with the strain GEM96 enhanced nodulation but did not correspond to an increased grain yield under field conditions. USDA110 was consistent in improving the grain yield of soybean cultivars Sultana and Siroca. On the other hand, GMM36 inoculation to Sultana and GEM96 inoculation to Siroca resulted in similar yields. Our results demonstrate that inoculation of locally adapted soybean cultivars with the indigenous isolates improves nodulation and yield attributes. Thus, to attain optimal symbiotic performance, the strains need to be matched with specific cultivars.

Phytotoxicity of fungicide coated sugar beet seed depends on growth condition.

Fungicide-coated seed protects sugar beet plants from soilborne diseases, but seedlings coming from coated seeds often encounter phytotoxicity under field conditions. To understand the phytotoxic impact, fungicide-coated seed and the uncoated seed of two cultivars were sown with holes or no holes in plastic trays in greenhouse conditions. Our study demonstrated without fungicide coat on sugar beet seed and holes in plastic trays resulted in just above 90% germination. While fungicide-coated seed and no hole's underneath trays- showed the lowest germination (>20%). Fungicide-coated seed, having holes in plastic trays showed 90% germination. No fungicide coat on seed, having no hole's underneath trays showed 70% germination. We further estimated the percentage of stunted seedlings in both cultivars. Fungicide-coated seed with holes underneath plastic trays showed above 5% stunted seedlings while fungicide-coated seed, having no hole's underneath trays- showed the highest percentage of stunted seedlings (>10%) in both cultivars. In summary, our data demonstrated that the phytotoxicity of fungicide-coated sugar beet seed depends on growth conditions.