4种牧草不同生长期C、N生态化学计量特征

Carbon and nitrogen stoichiometry at different growth stages in legumes and grasses

在甘肃庆阳(降水量517 mm)和榆中(降水量350 mm)的大田栽培条件下,研究了3种豆科牧草陇东苜蓿(Medicago sativacv.Longdong)、红豆草(Onobrychis viciaefolia)和箭筈豌豆(Vicia sativa)以及1种禾本科牧草一年生黑麦草(Lolium multiflorum)主要生长期的C、N含量及计量比变化。结果表明,不同生长期牧草有机碳含量差异不大;全氮含量随生长期呈降低趋势或在孕穗(蕾)期较低,叶全氮含量高于茎和根;C/N随生长期呈增加趋势或在孕穗(蕾)期较高,叶C/N低于茎和根,禾本科牧草C/N高于豆科牧草。榆中一年生黑麦草C/N高于庆阳,而豆科则相反。牧草C/N随生长期的变化与不同植物不同阶段C同化和N吸收有关。

This study was aimed to investigate carbon and nitrogen stoichiometry at different stages in legumes and grasses by comparing 4 different species under a field trial.For the content of organic carbon（OC）,it changed little at different growth stages.Total nitrogen（TN） content showed a decreasing tendency with growth stage or was less at the booting stage.Leaf TN content was greater than those in stem and root.With the changes in OC and TN contents,C/N showed an increasing tendency with growth stage or was greater at the booting stage.Leaf C/N was less than those in stem and root,and grass C/N was greater than that in legume.C/N of annual ryegrass in Yuzhong site was greater than that in Qingyang,while for legumes,it was less.The results suggested that the change in C/N with growth stage is closely correlated with carbon assimilation and nitrogen absorption of plants at different growth stages.