泡桐生长季节中叶片养分吸收变化规律的研究
The Nutrients Changes of Paulownia's Leaves in the Growing Season
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摘要: 研究了河南省商丘市2年生泡桐一个生长季节的养分变化情况及不同冠层养分状况。结果表明:在自然状况下,从出叶到落叶的整个生长过程中:①N元素的浓度是呈锯齿状下降趋势,最高值出现在5月末,为42.0g·kg-1,最低值出现在11月中旬,为21.5g·kg-1;P元素浓度是在生长季开始时较高,最高为2.5g·kg-1,到6月份以后基本趋于平稳,到10月份,又呈现下降趋势直到落叶,最低为1.2g·kg-1;K元素浓度在生长季开始时较高,最高为14g·kg-1,到6月份以后基本趋于平稳,直到9月底。10月份呈现下降趋势,从11月开始又基本稳定直到落叶,最低值为6.6g·kg-1;②整株树的养分积累状况中,N、P、K三种元素呈现出相似的变化规律,在开始略有下降,随后是一直增长,到7月份达到最高,N、P、K最高积累量分别为7.26g·株-1、0.37g·株-1、2.3g·株-1,之后开始下降,到9月份降到最低,N、P、K最低积累量分别为3.2g·株-1、0.16g·株-1、0.96g·株-1,随后又开始缓慢增长,直至落叶;③单叶片的营养元素的积累量是持续增长的;④不同冠层的N、P、K浓度差异不显著。Abstract: The Nutrients changes and the nutrient levels in different canopy layers of 2-year-old Paulownia fortunei Yulinensis in a growing season were studied under the natural condition. The results showed that: ①N concentration decreasesd as a saw shapes in the whole growing season. The highest was 42.0 g·kg-1; the lowest was 21.5 g·kg-1. P concentration decreased in the beginning and extended to be steady from June to October, then, kept the descending trend again. The highest was 2.5 g·kg-1; the lowest was 1.2 g·kg-1. K concentration decreased in the beginning and extended to be steady from June to October, then, kept the descending trend till November, and extended to be steady again. The highest was 14 g·kg-1; the lowest was 6.6 g·kg-1. ②The nutrient content of a whole tree showed descending trend in the beginning and turned to increasing trend till July and decreased till September and increased slowly till the end of the growing season. The highest contents of N,P,and K were 7.26 g·tree-1,0.37 g·tree-1,and 2.3 g·tree-1 which appeared in the end of July;and the lowest was 3.2 g·tree-1,0.16 g·tree-1,and 0.96 g·tree-1 which appeared in September. ③The nutrient content(N,P and K) per leaf kept increasing in the whole season. ④ There was no difference for nutrient element content in different canopy layers.