洱海4种沉水植物叶片的光合色素组成及C、N、P化学计量特征对水深的响应

Leaf carbon,nitrogen and phosphorus stoichiometric characteristics and photosynthetic pigments composition of four submerged macrophytes in response to various water depth in Lake Erhai,China

水深与水体的多个环境要素(如光照、温度等)密切关联.因而水深会影响沉水植物的生长、繁殖和生理生化特征,包括叶片的光合色素组成和C、N、P化学计量特征.本研究通过对洱海4种沉水植物苦草(Vallisneria natans)、微齿眼子菜(Potamogeton maackianus)、光叶眼子菜(Potamogeton lucens)和篦齿眼子菜(Potamogeton pectinatus)在不同水深梯度的叶片色素组成和C、N、P化学计量特征进行分析,以阐明水深对这些指标的影响规律和机制.结果表明:水深对4种沉水植物叶片光合色素组成和C、N、P化学计量特征的影响具有种间差异性;苦草、微齿眼子菜和光叶眼子菜叶片N含量,苦草和光叶眼子菜叶片P含量都与叶片叶绿素含量呈显著正相关;苦草叶片N含量随水深增加而增加,可能是由苦草为应对深水弱光胁迫而加强光合色素和蛋白的合成导致的,而磷含量的增加可能还受其他因素的影响.

Numerous environmental factors,such as light and temperature,vary a lot with water depth and these factors to a large extent determine the performance of plants. Therefore,water depth may affect the physiological and biochemical characteristics of submerged macrophytes,including leaf carbon,nitrogen and phosphorus stoichiometric characteristics and photosynthetic pigments composition. In order to examine howsubmerged macrophytes respond to water depth,we measured these parameters of four sub-merged macrophytes along water depth in Lake Erhai. Our results showthat： responses of the measured parameters of macrophytes to water depth were species-specific; the leaf nitrogen contents of Vallisneria natans,Potamogeton maackianus,Potamogeton lucens and leaf phosphorus contents of V. natans,and P. lucens were positive correlated with leaf chlorophylls; both leaf nitrogen and phosphorus content of V. natans increased with water depth. The mechanism behind the increase of nitrogen content in leaves with water depth may be that V. natans produced more chlorophylls and protein to adapt to the lowlight levels at deeper sites,while increase in phosphorus content of V. natans was affected by other processes besides adapting to lowlight.