摘要
以内蒙古呼伦贝尔草甸草原放牧草地和围封草地为实验样地,通过对两种样地羊草的水分关系、气体交换、渗透调节等生理生态学特性进行测定分析,比较研究放牧干扰对羊草的光合特性的影响。结果表明,在放牧处理下,羊草对水分亏缺更加敏感,通过降低蒸腾速率、提高水分利用效率(WUE)来应对放牧干扰。羊草能够提高叶绿素含量、改变电子流动方向、提高实际光化学量子产量(ΦPSⅡ)活性、增强Rubisco酶活性、提高光合氮、磷利用效率(PNUE、PPUE)适应放牧干扰,利于有机物积累。放牧和围封样地羊草净光合速率日变化都呈"双峰型",出现"午休现象",受气孔因素和非气孔因素的共同限制。在光合能量分配上,两种样地羊草PSⅡ的最大光化学量子产量(Fv/Fm)均出现光抑制现象,放牧样地羊草在光照较强时增加非光化学猝灭(NPQ),而在光照适宜时增加光化学猝灭(qP),将更多的能量用于光合反应中心,放牧干扰下羊草对能量的分配和利用更加迅速灵敏。因此,适宜放牧能够促进羊草的生长发育,维持草地较高的生产力,为内蒙古草甸草原生产力的恢复提供一定的理论依据。
In a study of grazed and ungrazed(fenced)plots in meadow steppe grassland located at Hulun Buir,Inner Mongolia,we investigated the diurnal pattern of ecophysiological behavior in Leymus chinensis,including water relations,gas exchange characteristics,light interception,osmotic adjustment and osmolytes,L.chinensis was sensitive to water deficit and able to cope with grazing disturbance by decreasing transpiration rate(T r)and increasing water use efficiency(WUE).In response to grazing disturbance,L.chinensis showed a range of adaptations,including increased chlorophyll content,increased activity ofΦPSⅡand Rubisco,increased tissue concentrations of nitrogen and phosphorus,increased photosynthetic utilization efficiency(PNUE,PPUE)and assimilate accumulation,and changed electron flow(ETR).Photosynthetic rate(P n)in both grazed and fenced plots displayed a mid-day depression,attributable to a combination of stomatal and nonstomatal factors.Similarly,the maximum photochemical quantum yield(F v/F m)of PSⅡin both grazed and fenced plots showed photoinhibition.L.chinensis in grazed plots displayed increased non-photochemical quenching(NPQ)and photochemical quenching(qP)with diurnal fluctuation linked to light stress.From these results it is deduced that L.chinensis in grazed plots could absorb more light energy in the photosynthetic reaction center,and respond more rapidly and sensitively.Thus,moderate grazing disturbance can promote growth of L.chinensis and maintain a higher productivity in meadow steppe grassland,than in ungrazed grassland.These findings therefore provide a scientific basis for planning productivity restoration in meadow steppe grassland in Inner Mongolia.
作者
张子荷
龚吉蕊
晏欣
黄永梅
安然
祁瑜
张梓瑜
刘敏
ZHANG Zi-he;GONG Ji-rui;YAN Xin;HUANG Yong-mei;AN Ran;QI Yu;ZHANG Zi-yu;LIU Min(State Key Laboratory of Earth Surface Processes and Resource Ecology,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China)
出处
《草业学报》
CSCD
北大核心
2018年第11期36-48,共13页
Acta Prataculturae Sinica
基金
国家自然科学基金面上项目(41571048)
国家重点研发计划课题(2016YFC0500502)
国家重点基础研究发展计划(973计划)(2014CB138803)资助。
关键词
放牧
羊草
气体交换特性
荧光特性
Rubisco酶活性
grazing
Leymus chinensis
gas exchange characteristics
chlorophyll fluorescence characteristics
Rubisco activity
