氮添加降低盐渍化草地赖草非结构性碳水化合物含量

Nitrogen Addition Decreased the Non-structural Carbohydrates Content of Leymus Secalinus in a Salinized Grassland

氮沉降全球化对草本植物不同器官非结构性碳水化合物(Non-structural carbohydrates,NSCs)的影响尚不清楚。本研究依托山西右玉黄土高原草地生态系统国家定位观测研究站2017年建立的不同水平氮添加试验平台,探究氮添加对赖草(Leymus secalinus)叶片和茎秆中的NSCs(可溶性糖、淀粉)含量及其比例的影响。结果表明:茎秆中可溶性糖、淀粉和NSCs含量显著高于叶片;氮添加降低了叶片和茎秆可溶性糖、淀粉、NSCs含量和可溶性糖∶淀粉比值,茎秆可溶性糖、淀粉和NSCs含量对氮素添加的响应更敏感;土壤无机氮含量、土壤pH值和土壤速效N∶P比值与叶片和茎秆中的可溶性糖、淀粉、NSCs含量和可溶性糖∶淀粉比值显著相关,而土壤有效P含量与这些指标无显著相关性。本研究结果表明植物不同器官NSCs含量和计量格局对氮添加呈现非线性饱和响应,但响应大小在植物器官间存在较大差异。

How the global nitrogen deposition affects the content of non-structural carbohydrates(NSCs)(soluble sugars,starches,and their proportions)in different organs of herbaceous plants remains unclear.To investigate the effects of nitrogen addition on NSCs,(such as soluble sugars,starch)and their proportions in leaves and stems of Leymus secalinus,by taking advantage of a field N addition experiment in a salinized grassland in the National Observation and Research Station of Grassland ecosystem in Youyu Loess Plateau of Shanxi Province.Results showed that the contents of soluble sugar,starch and NSCs in stem were significantly higher than those in leaves.The contents of soluble sugar,starch,NSCs and soluble sugar:starch ratios in leaves and stems were decreased by nitrogen addition,and the contents of soluble sugar,starch and NSCs in stems were more sensitive to nitrogen addition.Regression analysis showed that soil inorganic nitrogen,soil pH and soil available N∶P significantly affected soluble sugar,starch,NSCs and soluble sugar:starch.These results highlighted that the NSCs content and stoichiometric ratio of different plant organs showed non-linear and saturated responses to nitrogen addition,but the degree of response varied greatly among plant organs.