杂交水稻加工、外观品质性状间接选择的数学模型研究

利用19个优质杂交水稻品种（组合）,采用双向逐步筛选,求出加工和外观品质性状与产量性状的最优相关子集,建立了品质性状的回归方程,并对子集作了广义相关分析。结果表明千粒重、穗长与糙米率、整精米率、垩白粒率的相关已反映了品质性状与产量性状相关的主要信息（90％以上）,千粒重在21.96～27.64g、穗长在21.18～26.07cm范围内,增大千粒重可提高糙米率,但整米率下降、垩白粒率上升,适当缩短穗长可提高糙米率和整精米率,降低垩白粒率。     

Plant–plant interactions and soil moisture might be important in determining ozone impacts on grasslands

Ozone effects on plant species mixtures could depend on the characteristics of the species involved, their mixing ratio, or on environmental conditions. Predicting long-term effects on the dynamics of plant communities requires an understanding of the interactions involved. The present experiment was designed to determine the effects of ozone on grassland species in relation to mixing ratio and soil water content (irrigation) using binary mixtures. The grass Trisetum flavescens was grown in potted replacement-series mixtures with Centaurea jacea (Experiment A) or Trifolium pratense (Experiment B). The plants were exposed to three concentrations of ozone in open-top chambers in two irrigation treatments. Total above-ground dry weight over three growth periods was measured. The competitive ability of T. flavescens was expressed as the competitive ratio ( CR _T). In Experiment B, total above-ground dry weight was reduced by elevated ozone and by reduced soil moisture, and significant interactions were found for ozone × irrigation and ozone × ratio. In Experiment A these effects were not significant. Under well watered conditions, CR _T tended to be reduced by elevated ozone in Experiment A, but increased significantly in Experiment B, indicating the importance of the competing species in modifying the ozone effect on T. flavescens . In both experiments reduced irrigation decreased the magnitude of ozone effects on biomass production, which could be related to observed reductions in specific leaf conductance. The results suggest that under well watered conditions the effect of elevated ozone on the competitive balance between species depends on the species mixture, but that the mixing ratio is less important.     

Logistic回归模型及其在昆虫学中的应用

介绍了应用Logistic回归分析对二值反应的试验数据进行分析的方法 ,以及Logistic回归分析模型参数估计及其统计检验的方法 ,并结合 1个实际例子说明了Logistic回归模型的应用。