匐枝青藓(Brachythecium procumbens)对重金属铅污染的光合特性响应

利用人工移植盆栽方法,包括对照在内,共设置11个不同浓度Pb处理,研究Pb污染对匐枝青藓各种光合色素含量及净光合速率的影响。结果表明,各种光合色素对铅污染的响应敏感性不同,叶绿素a和类胡萝卜素都很敏感,叶绿素b相对较差。短时间(7d)和低浓度的铅污染(0.2~0.5mmol.L-1)时,匐枝青藓配子体中各种光合色素的含量显著高于对照。随着铅污染时间的延长(≥14d)和浓度的增高,各种光合色素含量则随着铅浓度升高而逐渐下降。铅污染时间越长,浓度越高,光合色素含量降低幅度越大,其中叶绿素a含量降低最为关键。匐枝青藓的净光合速率在铅污染状态下也发生了显著变化,短时间污染下,随着铅污染浓度增高呈现出明显的先升后降的趋势,但长时间高浓度铅污染时,其下降速度和幅度更大,与对照相比,50%净光合速率的铅污染浓度阈值更低。匐枝青藓配子体各种光合色素的含量变化和净光合速率的变化可以作为监测环境重金属铅污染的生理指标,进行长期定性地指示区域环境重金属铅污染的状况。

Response of photosynthetic characteristics in moss Brachythecium procumbens to lead pollution

In order to study the influence of Pb pollution on photosynthetic pigments and net photosynthetic rate of Brachythecium procumbens,11 groups including contrast was set up with different Pb concentration.The sensitivity of different phtosynthetic pigments to Pb pollution was different,both chlorophyll a and carotenoid were sensitive to Pb while chlorophyll b was not obviously sensitive to Pb.Dealing with Pb of 0.2~0.5mmol/L,the contents of photosynthetic pigments in the gametophyte of Brachythecium procumbens were significantly more than contrast with short dealing time(7 days).By extending time(≥14d) and increasing the Pb concentration,the contents of photosynthetic pigments decreased gradually.The longer polluting time with the higher polluting concentration,the decreasing extent of the contents of photosynthetic pigments was more obvious.Among all photosynthetic pigments,the decrease of the content of chlorophyll a was the most important.On the other hand,the net photosynthetic rate of Brachythecium procumbens changed obviously under the pollution of Pb.If the polluting time was short,the content of net photosynthetic rate increased first and decreased then.While polluted with higher concentration and longer time,the decreasing speed and extent were quicker.Comparing with the contrast,the liminal value of th Pb concentraion of 50% net photosynthetic rate was much less.To the gametophyte of Brachythecium procumbens,the changes of the contents of photosynthetic pigments and the net photosynthetic rate may be used as the physiological index to chronicly and qualitatively indicate the information of Pb pollution in regional environment.