柳杉细根衰老过程中的养分内循环

Nutrient Internal Cycling in Cryptomeria fortunei Fine Root with Senescence

将柳杉细根剥离土壤,加速细根衰老,测定并分析柳杉细根衰老期间不同根序细根的N,P,K及Ca浓度变化以及N,P,K浓度与Ca浓度比值的变化趋势。结果表明:1)在柳杉细根死亡过程中,N及K存在明显的内循环,Ca内循环不明显,P没有内循环;2)养分内循环首先出现在1级细根,其次是2和3级细根,表明细根衰老和死亡顺序与生长顺序相反;3)养分回输表现为阶段性,1级细根首先回输到2级细根,2级细根再回输到3级细根;4)柳杉细根中N,P,K浓度变化趋势和它们与Ca浓度比值的变化趋势基本一致。

The fine roots of Cryptomeria fortunei were excavated from soil in order to accelerate the root senescence. The concentration changes of N,P,K,Ca in different order fine roots of Cryptomeria fortunei were measured in the course of senescence. The results showed as follows：1） There was obvious inner circle of N and K,however not significant inner circle of Ca,and no any inner circle of P,during dying of the fine roots. 2） The inner circle of nutrients firstly appeared in the 1st order roots,followed by the 2~ nd order and the 3~ rd order roots,which suggested the sequence of caducity and death was reverse to that of growth. 3） The nutrient flow exited different phases,that is,nutrients flowed from the 1~ st order to the 2~ nd order then to the 3~ rd order of fine roots. 4） There was the same change trend between the concentration of N,P and K and the ratios of N /Ca,P/Ca and K/Ca ,which suggested Ca could be as an indicator of other elements as far as inner circle were concerned .