蓝桉幼林不同生长期的叶片营养元素含量分析

Content Analysis on Nutritive Elements in Leaves of Eucalyptus globulus Sapling Forest of Different Growth Period

１９９２～１９９６年对不同年龄蓝桉幼林各生长季节叶片的５种主要营养元素含量进行了分析研究。结果显示，蓝桉幼林叶片中Ｎ、Ｐ元素的含量夏季高于冬季；Ｎ含量第１、２年较高，各年间差异不显著；Ｐ含量各年间差异显著，第３年含量最高。元素Ｋ、Ｃａ、Ｍｇ的含量各年间差异显著，含量随林龄增加而增加，２５年以后达到高峰，之后由于“组织稀释”，浓度有所下降。施肥能提高叶片中Ｎ、Ｋ、Ｃａ元素的含量；由于施肥使蓝桉生长量明显提高，叶片中Ｐ、Ｍｇ元素含量下降，“组织稀释”现象明显。

From 1992 to 1996,the contents of the 5 main nutritive elements in leaves of different age Eucalyptus globulus sapling forests in each growth season were analysed and studied, the results indicated that the contents of N and P in summer were higher than those in winter, N content in the first 2 years were quite high and P content in the third year was the highest, N content difference between different years was not significant while that of P was significant, the content differences of K, Ca and Mg between different years were significant, with the increase of forest age, the contents of K, Ca and Mg increased and reached their peak values two and a half years later, after that, the concentration decreased somewhat because of “tissue dilution”,the contents of N, K and Ca in leaves could be increased by appling ferti lizer. Because of the effect of “tissue dilution”,the remarkably increased increment by fertilization caused abvious decrease of the contents of P and Mg.