云雾山草地优势种的光合生理特性对光强的响应

Response of Photosynthesis Physiological Characteristics of Predominant Species to Simulated Photosynthetic Radiation Intensity in Yunwu Mountain Grassland

研究了云雾山自然保护区主要优势种的光合生理特性对模拟光强的响应。研究结果表明,随光照强度的增加,4种植物的光合速率先增大后减少,蒸腾速率增加。本氏针茅的水分利用效率先增大后减少,铁杆蒿、大针茅和厚穗冰草的WUE呈一直增大趋势。4种植物的光合速率和水分利用效率在生长旺季7月份最大,生长末季9月份最小;蒸腾速率则表现为8月份最大。不同植物间最大光合速率的顺序为铁杆蒿>大针茅>厚穗冰草>本氏针茅;蒸腾速率大小顺序为本氏针茅>厚穗冰草>大针茅>铁杆蒿;水分利用效率的顺序为铁杆蒿>厚穗冰草>大针茅>本氏针茅。叶绿素荧光参数表明,随光强的增加,光能捕获效率(Fv′/Fm′)、实际光化学效率(PhiPSⅡ)和PhiCO2降低,热耗散(NPQ)上升。

Response of the eco-physiological characteristics to simulated photosynthetic radiation intensity in Stipa bungeana , Artemisia sacrorum , Stipa grandis, Aneurolepidium dasystachys leaves was investigated. Results showed that with increasing irradiation, Photosynthetic rate（P, ） was increased in lower density irradiation, hut was reduced in higher density irradiation, transpirationrate（T,） rate was enhanced with increasing irradiation. WUE for Stipa bungeana rose with increasing irradiation at first and then declined despite the intensified irradiation. WUE for Stipa grandis, Artemisia sacrorum, and Aneurolepidium dasystachys were enhanced with irradiation gradually. With growthmidseason, P, and WUE of the four species reacheda maximum in July and a minimum in September, while Tr reached a maximum in August. The species ranked in the descendant order of Artemisia sacrorum, Stipa grandis, Aneurolepidium dasystachys, and Stipa bungeana in terms of the max Pn; in the descendant order of Stipa bungeana , Aneurolepidium dasystachys, Stipa grandis, and Artemisia sacrorum in terms of Tr; and in the descendant order of Artemisia sacrorum, Aneurolepidium dasystachys, Stipa grandis, and Stipa bungeana in terms of WUE. The chlorophyll fluorescence parameter indicated that the conversion efficiency of primary light energy under light （Fv＇/ Fm＇） of PSII, actual PSII efficiency （PhiPSII）, and PhiCO2 declined in line with the CO2 concentration, but the nonphotochemical quenching coefficient （NPQ） ascended.