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苏铁由于自然分布在南方,人们便习惯把它归入温室花卉。但在实践中我们发现苏铁有时并不像温室花卉那样娇气,在冬季还能表现出出人意料的耐寒性。1999年冬季,我们这里出现了4～5天-10.2℃的低温,但几处露天地栽的苏铁在没有任何防寒措施的情况下却未遭受冻害。当然也不是所有时候它的耐寒性都那么好,2004年冬季我们这里虽未出现-10℃的极端低温,却出现了连续26天-4℃～-7℃的持续低温,结果露天苏铁遭受了不同程度的冻害,甚至有少数死亡。究竟什么情况下苏铁易遭受冻害呢?据我仔细观察,有以下五种情形:
Because of the natural distribution of the cycads in the south, people are accustomed to categorizing them as greenhouse flowers. In practice, however, we found that cycads are sometimes not as delicate as greenhouses and flowers, and show unexpected cold tolerance in winter. In the winter of 1999, we experienced a low temperature of 4 ~ 5 days and a temperature of -10.2 ° C. However, some open-planted cycads did not suffer any frost damage without any preventive measures. Of course, not all the time when its cold tolerance is so good, although we here in 2004 winter did not appear -10 ℃ extreme low temperature, but there have been continuous 26 days -4 ℃ ~ -7 ℃ sustained low temperature, the results of open-air suede suffered Different levels of frost damage, and even a small number of deaths. After all, what is the case when the Soviet Union is susceptible to frost damage? According to my careful observation, there are the following five situations: