OVERWINTERING OF THE RICE ORANGE LEAF MLO IN GUANGDONG PROVINCE Critical Index Analysisof Safe Over-wintering Rate ofWinter Rapeseed (Brassica rapa) in Cold and Arid Region in North China THE IMPORTANCE OF CULTIVATION MEASURES TO THE CONTROL OF WHEAT POWDERY MILDEW Impact of temperature increment before the over-wintering period on growth and development and grain yield of winter wheat.