氮素营养对肯氏南洋杉幼苗生长、根系活力及氮含量的影响

Effects of Exponential Nitrogen Loading on Growth,Root Activity and N Content of Araucaria cunninghamii Seedlings

为了探索不同氮素水平对肯氏南洋杉苗期生长的影响,确定其适宜施氮量,采用指数施肥法,设置0,50,150,250,350,550,750和950 mg·株-18个施肥处理,在温室开展肯氏南洋杉幼苗氮素施肥试验。结果表明:1)肯氏南洋杉幼苗的苗高、地径、生物量起先随施氮量的增加而增大,当施氮量为550 mg·株-1时达到峰值,继续增大呈现出不同程度的下降;根冠比随施氮量的增加呈现递减,但影响不明显;2)肯氏南洋杉幼苗的根系活力随施氮量的增加呈先升高后下降的趋势,当施氮量为550 mg·株-1时,根系活力最大;3)通过拟合苗木生物量、叶片氮含量与施氮量的响应曲线,确定肯氏南洋杉幼苗的充足施肥量和最佳施肥量分别为558.82和573.55 mg·株-1。综合上述研究结果得出:肯氏南洋杉幼苗的最佳施氮范围为550～575 mg·株-1。

In order to determine the optimal nitrogen amount for Araucaria cunninghamii, an exponential fertilization trial was conducted with 8 nitrogen levels （0,50,100,150,250,350,550,750, and 950 rag- seedling- l ） to research the effects of different nitrogen levels on height,root-collar diameter （RCD） ,biomass,root activity and N content in leaves of A. cunninghamii. The result showed that： 1 ） Height, RCD, biomass of A. cunninghamii seedlings increased with the increase of nitrogen supply,up to 550 mg ~ seedling 1 ,over which growth performance and biomass were stable. The root shoot ratio slightly decreased with increasing nitrogen fertilization,but the differences were not significant. 2） Root activity increased as the nitrogen fertilization increased from 0 to 550 mg· seedling-1 and then decreased from 550 to 950 mg · seedling- t. 3 ） From the response curves of seedling dry mass and N content to the increasing N supply, the sufficient and optimum nitrogen loading rates for A. cunninghamii seedlings were found to be 558.82 and 573.55 mg· seedling t, respectively. Based on these results,it could be concluded that 550 -575 mg. seedling-1 would be the optimal nitrogen amount for A. cunninghamii seedlings.