Abundance and Diversity of Soybean-Nodulating Rhizobia in Black Soil Are Impacted by Land Use and Crop Management

Abstract

To investigate the effects of land use and crop management on soybean rhizobial communities, 280 nodule isolates were trapped from 7 fields with different land use and culture histories. Besides the known Bradyrhizobium japonicum, three novel genospecies were isolated from these fields. Grassland (GL) maintained a higher diversity of soybean bradyrhizobia than the other cultivation systems. Two genospecies (Bradyrhizobium spp. I and III) were distributed widely in all treatments, while Bradyrhizobium sp. II was found only in GL treatment. Cultivation with soybeans increased the rhizobial abundance and diversity, except for the soybean monoculture (S-S) treatment. In monoculture systems, soybeans favored Bradyrhizobium sp. I, while maize and wheat favored Bradyrhizobium sp. III. Fertilization decreased the rhizobial diversity indexes but did not change the species composition. The organic carbon (OC) and available phosphorus (AP) contents and pH were the main soil parameters positively correlated with the distribution of Bradyrhizobium spp. I and II and Bradyrhizobium japonicum and negatively correlated with Bradyrhizobium sp. III. These results revealed that different land uses and crop management could not only alter the diversity and abundance of soybean rhizobia, but also change interactions between rhizobia and legume or nonlegume plants, which offered novel information about the biogeography of rhizobia.

Morphological and Biochemical Characterization of Soybean Nodulating Rhizobia Indigenous to Zambia

“…On the other hand, Sadowsky et al (1983) have shown that slow-growing rhizobia such as Bradyrhizobium, can have a high level of tolerance to acid conditions (pH 4.5) while fast-growers can tolerate alkaline conditions of pH 9 and 9.5 in growth media. This observation in-vitro agrees with what has been observed in China that Ensifer (acid producers, fast-growers) are dominant in alkaline-saline soils while Bradyrhizobium japonicum (alkaline producers, slow-growers) in acid soils (Yan et al, 2014). Both of these studies, indicate that fast-growers are relatively more alkali tolerate and acid sensitive than slow growers.…”

Prospecting of efficient rhizobia for peanut inoculation in a Planosol under different vegetation covers

“…The effects of changes in the land use (Jesus et al, 2009). In a study conducted in northeastern China, communities of soybean-nodulating bacteria had higher diversity in soils covered with grassland compared with those coming from fallowing soils, or making use of monoculture or crop rotation (Yan et al, 2014). The lower diversity found in the area cultivated with sugarcane in the present study may be due to the large anthropic interference and the consequent process of degradation suffered by this ecosystem, with deforestation of the Atlantic Forest and cultivation of the sugarcane monoculture for several years.…”

Rhizobium anhuiense as the predominant microsymbionts of Lathyrus maritimus along the Shandong Peninsula seashore line

“…Approximately 50-80 nodules were collected from 15 to 20 plants at each sample site. Before isolation, nodules were immersed in sterile deionized water overnight at 4 • C, then the rehydrated nodules were surface-sterilized in 4% NaClO (w/v) solution using a standard protocol [29,32]. The surface-sterilized nodules were crushed and the liquid extract was streaked onto yeast mannitol plates (YMA) (yeast extract, 3.0 g; mannitol, 10.0 g; KH 2 PO 4 , 0.5 g; MgSO 4 ·7H 2 O, 0.2 g; NaCl, 0.1 g; distilled water, 1.0 L; pH 7.0).…”

“…The bacterial colonies obtained were repeatedly streaked onto the same medium two to three times in order to purify the isolates. The purified cultures were then maintained in 20% (v/v) glycerol at −80 • C for long-term preservation [29,32].…”