【作者】 何树斌； 沈禹颖； 杨惠敏；

【Author】 Shubin He Yuying Shen Huimin Yang (Collage of Pastoral Agriculture Science & Technology;Key laboratory of Grassland Agro-ecosystems, Ministry of Agriculture,Lanzhou University,Lanzhou 730020,China)

【机构】 兰州大学草地农业科技学院农业部草地农业生态系统学重点开放实验室；

【摘要】 生态系统元素平衡是植物响应当前全球气候变化的研究热点和焦点。无论是从生物化学还是化学计量学的角度看,植物体内碳氮磷存在一个平衡关系,表现出植物有一个适应外界环境的的C/N、N/P、C/P比值。本文探讨了黄土高原地区处于初花期到盛花期代谢水平最旺盛阶段的4龄和8龄紫花苜蓿碳、氮、磷含量及其C/N、N/P、C/P规律。结果表明,在水分限制的条件下,第一茬8龄苜蓿叶片碳同化能力强于4龄苜蓿,而第二茬随土壤水分条件的改善,茎叶氮、磷含量均高于第一茬,茎叶碳。第一茬苜蓿茎叶C/N比和C/P均高于第二茬,两茬苜蓿中4龄苜蓿C/N的变幅要大于8龄苜蓿,这进一步说明8龄苜蓿的抗逆性强于4龄苜蓿。对N/P的研究主要是体现在限制性元素上,本研究结果表明,第一茬茬苜蓿茎叶中N/P低于二茬,进一步的推论说明第一茬苜蓿不存在氮磷限制,但二茬盛花期紫花苜蓿受土壤氮素的限制,施氮将有助于再生生物量的累积。更多还原

【Abstract】 The balance of elements in plant is critical to plant growth and development.Either from the bio-chemical point of view,or from the perspective of chemometrics,the plants exist a suitable balance of carbon-nitrogen ratio(C/N),nitrogen and phosphorus ratio(N/P ).and carbon and phosphorus ratio(C/P ). The results indicated that carbon assimilation capacity in the first crop of alfalfa leaves 8-old are higher than at age 4 under the water restrictions,while the concentrations of nitrogen,phosphorus in stem and leaf in the second crop are higher than the first with improved soil moisture conditions.The C/N ratio and C/ P ratio in the first crop are higher than the second,the amplitude of C/N in 4 age are higher than 8 age.It is the evidence to show that the resistance of 8 age are higher than 4age.On the study of the N/P is primarily reflected in the restrictive elements. This study showed that the N/P of leaf in the first crop is less than the second and there is no nitrogen and phosphorus limit in the first crop of alfalfa.But in the second crop nitrogen will contribute to the cumulative renewable biomass.更多还原