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利用杂种优势,推广以单交种为主的杂交种,是玉米增产的有效途径。玉米属雌雄同株异位的异花授粉作物,其开花习性与气候条件关系密切。我国北方各省对玉米的开花习性进行过不少研究,认为影响玉米开花散粉的主要因素是温度和湿度。最适温度和相对湿度分别为25～28℃和70～90％;温度超过30℃和相对湿度低于60％时,开花很少;温度过高(38℃),则雄穗不开花。雄穗开花持续7～9天,以第三或第四天达到高峰,冷凉天气可长达12～13天,以每日上午7～11时开花最盛,
The use of heterosis, the promotion of cross-species-based hybrids, is an effective way to increase corn yield. Maize heterosexual hermaphrodite pollinated crops, the flowering habits and climatic conditions are closely related. In northern China, the flowering habits of maize have been studied quite a lot, and the main factors affecting the flowering of maize are temperature and humidity. The optimum temperature and relative humidity were 25 ~ 28 ℃ and 70 ~ 90% respectively. When the temperature was above 30 ℃ and the relative humidity was below 60%, the flowering was very little; when the temperature was too high (38 ℃), the tassel did not flowering. Tasmania flowering continued for 7 to 9 days to the third or the fourth day to reach the peak, cold weather can be as long as 12 to 13 days to 7 to 11 daily morning flowering Sheng,