Speaker
Description
Grain legume production in Europe remains low, despite their numerous benefits. On average, they occupy less than 2% of European acreage. For instance, soybean, a highly valued grain legume, accounts for a small proportion of total arable land in Central Europe, despite its potential. Commercial inoculants are commonly used to inoculate field-grown soybeans in Europe. However, nodulation efficiency has been continually low (Schmidt et al. 2015), necessitating the need to explore strategies to increase its growth and productivity. The objectives of this study were: (i) to evaluate the ability of naturalized Bradyrhizobium strain(s) to maximize soybean grain protein content, grain yields, and protein yields in field conditions (ii) to evaluate the extent to which the symbiotic performance of the strains is impacted by soil moisture.
The experiments were carried out in three consecutive seasons (2020–2022) at the experimental station of the Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg. Treatments were laid out in a slit-plot design with three factors, namely soybean cultivar, inoculant strain, and water supply. The three soybean cvs. were: Merlin, maturity group (MG) 000; Sultana, MG 000; and Siroca, MG 00. The inoculant strain consisted of three promising Bradyrhizobium strains (GMF14; GMM36; GEM96), previously isolated from Northern Germany. The water supply had two treatments, namely irrigated and rainfed. The isolates, as well as a reference strain (Bradyrhizobium diazoefficiens USDA110) and a noninoculated control, were tested in combination with the soybean cultivars.
Inoculation with the local isolates resulted in significant increases in grain yield compared to the commercial USDA110 strain. However, there were no statistical differences in grain protein or protein yields. While irrigation did not significantly affect crude protein content, it resulted in a 27% and 16% increase in grain and protein yields, respectively. Although irrigation increased grain and protein yield in all strains, it had a greater effect on the commercial USDA110 strain than on GMF14 or GEM96. This implies that GMF14 and GEM96 are more adaptable to the drought conditions in Northeast Germany than the standard USDA110. Inoculation with these promising local isolates of superior soybean cultivars has the potential to create a more resilient soybean cropping system in northeast Germany.
| Keywords | Bradyrhizobia; Protein; Soybean; Inoculation; yield variability |
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