红树植物叶片衰老过程中养分的内吸收

Study on the Nutrients Retranslocation of Mangroves During Leaf Senescence

研究了23种红树植物(15种真红树植物,8种半红树植物)叶片衰老过程中氮(N)、磷(P)内吸收率.结果表明:(1)真红树植物与半红树植物相比,其叶片营养元素含量相对较低(Nmass=17.3mg/g;Pmass=1.4mg/g),N、P含量随叶片衰老而减少;(2)大部分红树植物叶片氮磷比小于31,说明红树植物存在氮限制;(3)真红树植物氮内吸收率平均为63.6%,远高于半红树植物(52.2%)以及一般常绿植物(47.0%),但真红树植物磷内吸收(53.4%)和半红树植物(49.4%)不存在显著的差异.因此,真红树植物拥有更高的氮保存能力,使其更适应于在缺氮环境下生存.

In this paper, nitrogen （N） and phosphorus （P） retranslocation during leaf senescence in 23 mangrove species （15 specific true-mangroves, 8 specific semi-mangroves）are studied. The results are as follows. （1）In contrast to semi-mangroves leaves, mature leaves of true-mangroves are relatively low nutrient （N and P） concentration expressed on a dry mass basis （Nmass and Pmass mg/g）,with 17.3 mg/g for N and 1.4 mg/g for P respectively. N and P concentrations decrease with leaf senescence. （2） Leaf N/P ratios are in most instances ~31, suggesting N limitation. （3）N retransloeation efficiency （NRE） is average 63. 6 % in true-mangroves, which is greater than that in semi-mangroves （52. 2 %） or the general evergreen trees （47. 0%）. But there are no significant differences of P retransloeation efficiency （PRE） between true-mangroves （53. 4%） and semi-mangroves （49.4%）. This suggests that true-mangroves reliably have a high capability in nitrogen-conservation for some factors. And true-mangroves are physiologically adapted to live in lower N-supply environments.