快速失水下5种喀斯特植物离体叶片叶绿素荧光的响应

Response traits of the chlorophyll a fluorescence to saturation andsubsequent continuous dehydration in five karst plants

文章设置饱水及随后失水处理自然生长的5种喀斯特植物叶片,测定其叶绿素荧光参数,分析各植物光合过程的响应特征。结果显示:盐肤木(Rhus chinensis)PSII反应中心活性及电子传递受严重失水影响,而其稳定的光能转化及光化学效率得益于叶绿素浓度的不断增加;构树(Broussonetia papyrifera)和金银花(Lonicera japonica)的叶绿素浓度逐渐升高随后趋于稳定,构树PSII反应中心对失水敏感,其活性及光能转化对随后持续失水逐渐适应。金银花光合结构及PSII反应中心表现稳定;火棘(Pyracantha fortuneana)叶绿素浓度从第4小时开始增加,光合结构趋于稳定,电子传递速率及光能转化逐渐增加;杨梅(Myrica rubra)电子传递速率及光化学效率均较低。

The heterogeneity of karst habitat together with the diversity of plant adaptive mechanism makes the reasonable allocation of pioneer plant in karst regions very difficult,which affects the efficient governance of the degraded karst ecosystem.Research on the diversity of plant photosynthetic adaptive mechanism can help complete the anchorage of plants and heterogeneous karst drought habitats.In this work,the naturally-grown leaves of five karst plants were selected as materials and treated with saturation and subsequent continuous dehydration.The chlorophyll fluorescence parameters were determined,and the response traits of photosynthetic process were investigated,which provides a basis for the rapid evaluation of plant drought resistance.The results indicate that the leaf photosynthetic process of Rhus chinensis exhibits better adaptability to great variation of leaf water content,and the activity of PSII reaction center and electron transport rate are inhibited by high water stress.However,the stable light energy conversion can help maintain the photochemical efficiency,which is attributed to the increasing chlorophyll concentration.The leaf water retention capacities of Broussonetia papyrifera and Lonicera japonica are relatively high,the chlorophyll concentration increases with water losing and maintains stable subsequently.The PSII reaction center of Broussonetia papyrifera is sensitive to water loss,but the activity of PSII reaction center and light energy conversion efficiency show adaptability to the long-term continuous dehydration.The photosynthetic structure of Lonicera japonica is not damaged seriously,and the activity of PSII reaction center is stable.The leaf water retention capacity of Pyracantha fortuneana is worse than that of other plants,but the chlorophyll concentration increases significantly from the fourth hour.The stability of photosynthetic structure,electron transport rate and the portion of light energy absorbed by leaf that is used for photochemistry are better than that in Lonicera japonica under continuous dehydration conditions.Myrica rubra is a non-karst plant,of which the chlorophyll concentration decreases under long-term dehydration.The activity of the PSII reaction center is inhibited,and the photosynthetic structure is damaged.Meanwhile,the electron transport rate of Myrica rubra is too low to show significant variation as water losing continues,and the photochemical efficiency would be inhibited by the low electron transport rate.