CO_2浓度升高对沉水植物菹草叶表型及生理生化特征的影响

EFFECTS OF ELEVATED CO_2 CONCENTRATION ON PHENOTYPIC, PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS OF SUBMERSED PLANT POTAMOGETON CRISPUS LEAF

对菹草 (Potamogetoncrispus)叶在高CO2 (1 0 0 0± 50 μmol·mol-1 )和对照浓度 (约 380 μmol·mol-1 )下的表型及一些生理生化指标进行了比较研究。结果表明 :CO2 浓度升高明显地改变了菹草叶的表型特征 ,外形更为粗短 ,叶宽、单叶面积、单株总叶面积、叶面积率、叶重比明显增加 ,但特殊叶面积和叶长增加不明显。线性回归分析表明单株总叶面积和植株大小密切相关。异速生长分析表明叶面积的变化不是可塑性反应 ,而是受植株大小所制约。此外 ,CO2 浓度升高后植物的色素含量和一些化学物质含量明显改变。叶绿素a、叶绿素b、总叶绿素及类胡萝卜素含量减少 ,且叶绿素a b也降低 ;可溶性糖含量增加 ,而蛋白质。

The effects of elevated CO 2 concentration on growth and development of terrestrial plants have been studied intensively, but less scientific interest h as been raised on aquatic plants. In this study, a greenhouse experiment with su bmersed species Potamogeton crispus, one of dominant species in lakes along Yangtze River Basin, was studied comparatively in higher (1 000±50 μmol·mo l -1 ) and ambient (about 380 μmol·mol -1 ) CO 2 concentration to t e st whether CO 2 has significant impacts on phenotypic and some physiological an d biochemical characteristics as main effect. In addition, allometric analysis w as applied to distinguish whether phenotypic changes such as total leaf area are induced by environment (plastic) or plant size dependent (non_plastic). The res ults showed that phenotypic characteristics of P. crispus leaf in elevated C O 2 concentration changed significantly compared with that in ambient CO 2 concent ration. Leaf shape was more stubby, but leaf width, single leaf area, total leaf area per plant and leaf area ratio increased significantly in elevated CO 2 co ncentr ation. However, specific leaf area and leaf length did not differ between treatm ents. Total leaf area per plant was closely correlated with plant weight, indica ting that change in this phenotypic characteristic may depend on plant size. The result of allometric analysis certified that this change was a non_plastic resp onse, but plant size dependent. In addition, higher CO 2 concentration led to t he changes in pigment concentration. Chlorophyl a, chlorophyl b, total chlorophyl, carotenoid concentration and the ratio of chlorophyl a/b decreased in elevated CO 2 concentration. The soluble sugar concentration increased, but protein, N a nd P content decreased under higher CO 2 condition. It is concluded that elevated a tmospheric CO 2 concentration results in significant changes in some physiologi ca l and biochemical characteristics, especially increase of soluble sugar concentr ation, but not necessary in leaf phenotype. Maybe 'true' adjustment in leaf ph enotype is under strong genetic rather than CO 2 control.