干旱和复水对喀斯特石生穗枝赤齿藓水分及光合生理的影响

Effect of alternating wetting-drying on physiological features of water content and photosynthesis of Erythrodontium julaceum(Schwaegr.) Par.in karst habitat

研究了石生穗枝赤齿藓对喀斯特环境变迁的水分及光合生理适应,为喀斯特石漠化生态环境的恢复与治理提供依据。选择贵州普定石漠化区域交织型石生穗枝赤齿藓(Erythrodontium julaceum(Schwaegr.)Par.)为材料,测定水分和光合生理等指标。结果表明:干旱胁迫下石生穗枝赤齿藓水势(Ψs)、自由水含量(Va)、组织总含水量和相对含水量(RWC)降低,束缚水(Vs)、水分饱和亏(WSD)和Vs/Va比值增大,复水后各水分生理指标均有不同程度的恢复。RWC与qN负相关,与Fv/Fm、Yield、ETR、qP、Pn呈正相关关系;叶绿素含量总体呈出先升后降再升高的趋势。轻度干旱胁迫Pn逐渐下降,重度急剧下降,光合作用受到了严重的影响;随干旱胁迫进程蒸腾速率(Tr)的变化未见显著差异。复水后各荧光参数在轻中度胁迫下能恢复到正常水平,而重度胁迫较难恢复到对照水平。喀斯特石生穗枝赤齿藓具有适应岩溶干湿交替的水分代谢和光合生理机制,是石漠化地区植被恢复与重建过程中的先锋物种。

This study presents a theoretical foundation for recovering and controlling the environments of rocky desertification ecology.It relies on comparing the adaptability to habitat heterogeneity in karst rocky desertification areas with arid desert of karst and seasonal drought environments and analysis of moisture content and photosynthetic physiological adaptation.Taking E.julaceum growth on rock as the object,water content and photosynthetic physiological indexes are measured in the Puding City,Guizhou Province.The results show that the drought makes water potential(Ψs),free water content(Va),water content and relative water content(RWC)of E.jula⁃ceum decrease,bound water content(Vs),water saturation deficiency(WSD)and ratio of bound water content to free water content(Vs/Va)increase,leaf water-holding ability weakened,and transpiration rate(Tr)decreased.The response sensitivities of these indices to water’s action are different.With increase of drought,total chlorophyll content first rises and then drops,finally tends to increase.qN of three kinds of mosses is negatively correlated while Fv/Fm,Yield,ETR Pn and qP decline with drought are positively correlated.The Pn gradually declines in mild drought dehydration.After 48 h Pn falls sharply,photosynthesis is affected by the serious drought.Along with the process of drought,changes of transpiration rate(Tr)have no significant differences between species.Fluorescence parameters after re watering can be restored to normal levels in mild to moderate force,and severe force is more difficult to return to the control level.The epilithic mosses has strong drought resistance ability,water metabolism and photosynthetic physiological mechanism to adapt to the karst environment,indicating a pioneer species in the process of vegetation restoration and reconstruction in the karst rocky desertification areas.