Physiological and symbiotic variation of a long-term evolved Rhizobium strain under alkaline condition.

Physiological variation and adaptation of the long-term evolved rhizobia to alkaline environments where no host plant existence and the stability of their symbiotic properties when they are reinoculated to legume host remain unclear. A highly effective N-fixing Rhizobium yanglingense strain CCBAU 01603 was used as the ancestral strain and was cultured continuously with/without addition of extra alkaline reagent (KOH) in laboratory conditions for approximately 500 generations. Total 60 evolved clones obtained were checked for their adaptation to higher alkaline pH level and inoculated to their host plant Caragana microphylla to evaluate their symbiotic efficiencies.

Competition between rhizobia under different environmental conditions affects the nodulation of a legume.

Mutualistic symbiosis and nitrogen fixation of legume rhizobia play a key role in ecological environments. Although many different rhizobial species can form nodules with a specific legume, there is often a dominant microsymbiont, which has the highest nodule occupancy rates, and they are often known as the "most favorable rhizobia". Shifts in the most favorable rhizobia for a legume in different geographical regions or soil types are not well understood.

Quantification of the impact of land-use changes on ecosystem services: a case study in Pingbian County, China.

Pingbian Miao Autonomous County is one of the poorest rural areas in China. Land-use changes, mainly driven by agricultural expansion and deforestation, may significantly impact ecosystem services and functions, but such effects are difficult to quantify. In the present study, Landsat image data were combined with the published coefficients about the world and China ecosystem to quantify land-use and ecosystem service changes in the mountainous area.