摘要
分布在南亚热带金沙江干热河谷的攀枝花苏铁,普遍受蓝细菌侵染形成特殊的多级分枝珊瑚状根瘤簇。当年生树苗活瘤重可达8克/株,100年生370克/株。固氮活性在秋季一般为1.8—11.1μmolC_2H_4/g·f·w·h^(-1),它明显受光照和湿度影响,昼夜动态是白天活性明显比夜间高。苏铁固氮量从0.64—18.69毫克/株·小时,它在生态系统的氮循环中起良好作用。
The cycas distributed in the dry-hot inshajiang river valley in the south-subtropical region of China, infected by the cyanobacteria, form especial coral-like nodule clusters with multiply branches. The nodules are most numerous within 10cm below the soil surface. The living nodules of current seedlings amounted to 8 g per plant and those of over 100-year plants averaged 370 g. The nitrogen fixation activity is usually from 1.8 to 11.1 μmol/g.f.w.h^(-1) in the autumn, and is obviously influenced by light and soil moisture, Daily variation of N_2-fixing activity has shown that it is mhcu higher in daytime than at night. Nitrogen fixation amount for the cycas varied from 0.64 to 18.68 mg/plant.h^(-1). This suggests that it may play a certain role in the nitrogen cycle of the ecosystem.
关键词
攀枝花苏铁
根瘤
固氮
Cycas panzhihuaensis
Nitrogen fixation
