在进行乔灌木的引种时,经常遇到下列情况,即当把原产于高纬度地区的树种引入南方吋,虽然此时的气温和水分条件适宜于生长过程的正常进行,但常提早封顶。相反,当把原产于低纬度地区的树种引入北方时,封顶期有相当的延缓,甚至有不封顶现象,虽然此时气温已不适合其遗传性要求,在引种杨树和落叶松时,这一规律就表现得十分明显。根据国内外学者的分析和实验,证明这与不同纬度地区的昼夜日照长度有直接关系,与温度的相关性不显著。在生长季节,低纬度地区白天日照时数短,高纬度地区白天日照时数长,当把原产长日照地区的植物引进短日照地区时,秋天因得不到所需的长日照,而处于短日照条件下,因此封顶早,生长期缩短,如把低纬度地区的植物引进高纬度地区时,则园秋天得不到为封顶必要的短日照,就延迟了封顶,甚至不封顶。本文内的材料也证明这一点,但作者并无做详细阐述,特此补正。 In the introduction of shrubs and shrubs, it is often the case that the introduction of species originating in high latitudes into the south often captures them early, although the temperature and moisture conditions at this time are suitable for normal growth. On the contrary, when the tree species originating in low latitudes were introduced into the north, the capping period had been considerably delayed or even not capped. Although the temperature was not suitable for the hereditary requirements at this time, during the introduction of poplar and larch, The law is very obvious. According to the analysis and experiments conducted by domestic and foreign scholars, it is proved that there is a direct relationship between the diurnal length of day and night in different latitudes, and the correlation with temperature is not significant. During the growing season, the sunshine hours at daytime are low in low latitudes and the sunshine hours are long in daytime at high latitudes. When the plants in the native longriver area were introduced into the short-sunshine area in autumn, Due to the short daylight conditions, capped early and shortened the growing season. If plants in low latitudes are introduced into high latitudes, the fall of the garden will not be capped for the necessary short days in autumn, and the cap will be delayed or even not capped. The material in this article is also proof of this, but the author did not elaborate, hereby make corrections.