玉竹品质与主要生态因子的相关性

采用逐步回归、主成分分析和灰色关联度分析等方法，研究不同产地野生玉竹的有效成分(多糖、水溶物和醇提物)含量和抗氧化活性与主要生态因子的相关性.结果表明: 1月均温、7月均温、年降水量、无霜期、土壤pH和全钾含量是影响玉竹有效成分含量的主要生态因子，对玉竹有效成分含量变化的影响程度占99.0%.与土壤因子相比，气候因子对3种有效成分含量的影响较大；土壤全钾含量是对玉竹有效成分含量直接影响最大的因素，年降水量是最主要的决策因素，1月均温是最主要的限制因素.多糖和水溶物含量是影响玉竹抗氧化活性的主要因子，玉竹对DPPH自由基的清除能力随多糖和水溶物含量的增加而增大.

Screening and identification of denitrifying bacillus strain and its denitrification characteristics

By the methods of heating accumulation,nitrate-reduction gas production,and quantitative analysis of denitrification,a bacillus strain with high-efficient denitrifying capability named as TGR30 was isolated from the sediment of Wuliangsuhai Lake.The isolate was identified as Bacillus megaterium,based on its morphological feature,biochemical characteristics,and 16S rDNA sequence analysis.Single factor experiment was conducted to investigate the influences of medium carbon,C/N,salinity,pH,and dissolved oxygen on the denitrifying characteristics of the strain.When the medium salinity was 6% or the pH value was 12,the strain still had high nitrogen removal capability,and the optimal conditions for the nitrogen removal were the medium C/N ratio 14,pH value 8.0,and dissolved oxygen concentration 4 mg·L-1 when soluble starch was used as the sole carbon source.