Effects of inoculating nitrogen fixing bacteria Klebsiella sp.120on photosynthetic characteristics and mineral nutrient contents of sugarcane UING ~(15)N ISOTOPIC DILUTION METHOD TO DETERMINE THE QUANTIFICATION OF ASSOCIATION NITROGEN FIXATION BACTERIA SOIL FROM OAT ROOTS Changes of Nitrogenase Activity in Sugarcane (Saccharum officinarum L.)and Its Response to Innoculate Nitrogen Fixation Bacteria Distribution and Dynamics of Non-symbiotic Nitrogen Fixing Bacteria in Xilingol Grassland Soil Effects of Inoculating Associated Nitrogen Fixing Bacteria to Moso Bamboo Seedlings Growth