试述外界条件对植物性别分化的影响。
参考答案：
光周期对花内雌雄器官的分化影响较大。一般说来，短日照促使短日植物多开雌花，长日植物多开雄花。把雌雄异株的长日植物菠菜，经长日照诱导后，紧接着给予短日照。则在雌株上可以形成施花。
土壤条件对植物性别分化影响比较明显，一般来说，氮肥多，水分充足的土壤促进雌花℃绍撇渊紧狱烯可以促进黄瓜雌花的分化，赤霉素则促进黄瓜雄花的分化。另外生长调节剂矮壮素促迸雌花的分化，三碘苯甲酸则促进雄花的分化。
机械损伤可刺激乙烯生成促进黄瓜多开雌花。
Mr. White works in an office. He is very 1 and has no time to have a good rest. Every evening, when he comes back 2 his office, he’s always tired and wants to go to bed early. 3 his wife often has a lot of interesting things to tell him after supper. She doesn’t stop talking until he falls 4 . But it’s usually too late and Mr. White has to 5 early in the morning when she is asleep. One day the man 6 terrible and couldn’t（不能）go to work. He decided to go to 7 . And Mrs. White went with him. Before her husband said 8 was the matter with him, the woman had told the doctor all and the doctor understood（知道）why. He wrote a prescription(处方)。And when Mrs. White brought the medicine to the doctor, he said to her, “ 9 is for your husband and the pills are for you.” “For me?”the woman said in surprise, “I’m fine. I don’t need 10medicine” “I don’t think so, madam,” said the doctor. “They are sleeping pills(安眠药丸). Your husband will soon be all right if you take them.”
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