1.影响玉米制种授粉的主要因素 (1)温度。温度是影响玉米制种授粉的环境因素之一。玉米制种授粉的最适温度是25～28℃C,温度越高,花粉寿命越短。若遇35℃以上温度,授粉、受精就会受到阻碍;相反,温度低于18℃,会使父本雄穗不能开放,授粉亦不能正常进行。我县玉米制种在7月中下旬,日均气温在28℃以上,日最高温达35℃以上,授粉常常受到严重困扰,影响授粉的正常进行,是我县玉米制种产量低的原因之一。根据1994年对南七单交制种 1. The main factors affecting pollination of corn seed (1) temperature. Temperature is one of the environmental factors affecting pollination of corn seed. The optimum temperature of corn pollination is 25 ~ 28 ℃ C, the higher the temperature, the shorter the pollen life expectancy. In the case of temperatures above 35 ℃, pollination, fertilization will be hindered; the contrary, the temperature is below 18 ℃, will make the male tassel can not be opened, pollination can not be normal. Corn production in our county in late July, the average daily temperature above 28 ℃, the maximum daily temperature of 35 ℃ or more, pollination are often seriously hampered, affecting the normal pollination is my county corn seed production is low one. According to 1994 on the South seven single cross seed