植物生态学报 ›› 2013, Vol. 37 ›› Issue (6): 530-541.DOI: 10.3724/SP.J.1258.2013.00054

• 研究论文 • 上一篇    下一篇

狼针草光合特性对放牧干扰的响应

晏欣,龚吉蕊(),张梓瑜,黄永梅,安然,祁瑜,刘敏   

  1. 北京师范大学地表过程与资源生态国家重点实验室, 北京师范大学资源学院, 北京 100875
  • 收稿日期:2012-11-13 接受日期:2013-02-09 出版日期:2013-11-13 发布日期:2013-06-05
  • 通讯作者: 龚吉蕊
  • 基金资助:
    国家自然科学基金(40871031);国家自然科学基金(4103-0535)

Responses of photosynthetic characteristics of Stipa baicalensis to grazing disturbance

YAN Xin,GONG Ji-Rui(),ZHANG Zi-Yu,HUANG Yong-Mei,AN Ran,QI Yu,LIU Min   

  1. State Key Laboratory of Surface Processes and Resource Ecology, College of Resources Science and Technology, Beijing Normal University, Beijing 100875, China
  • Received:2012-11-13 Accepted:2013-02-09 Online:2013-11-13 Published:2013-06-05
  • Contact: GONG Ji-Rui

摘要:

以内蒙古呼伦贝尔草甸草原围封草地和放牧草地为实验样地, 通过对两种草地类型中狼针草(Stipa baicalensis)的光合特性、水分关系、植物渗透调节等生理生态学特性测定分析, 比较研究放牧干扰对狼针草的影响。结果表明: 在放牧干扰下, 狼针草通过增强核酮糖二磷酸羧化酶(RUBPCase)活性、叶绿素含量、改变电子流的方向和速率、增强光系统II (PSII)活性(p < 0.05), 促进同化物的累积和植物的补偿生长, 应对放牧干扰的影响。放牧干扰下狼针草的光合速率日变化曲线呈单峰型, 而围封草地中呈“双峰型”, 出现“午休”现象, 正午RuBPCase的羧化能力下降是造成围封草地狼针草光合“午休”的非气孔因素之一, 而磷元素的缺失可能是导致二磷酸核酮糖羧化酶(Rubisco)活性下降的原因。在光合能量分配方面, 两种样地狼针草的PSII最大光化学量子产量(Fv/Fm)均出现光抑制现象。放牧草地中狼针草对光照增强较为敏感, Fv/Fm值下降趋势明显(p < 0.05)。和围封样地相比, 放牧样地的狼针草光化学猝灭(qP)值升高, 而非光化学猝灭(NPQ)值降低(p < 0.05), 分配更多的能量于光合反应中心, 有利于同化物累积, 提高光合能力来适应放牧的影响。在放牧干扰下, 狼针草叶片水势与叶片含水量降低, 而渗透调节物质可溶性蛋白和可溶性糖含量增加(p < 0.05), 狼针草的蓄水性变弱, 需要通过增加体内渗透调节物质, 主动降低水势, 以保证从土壤中获取足够的水分维持自身生理活性。同时, 放牧干扰促进了狼针草对氮元素的吸收利用。放牧样地中狼针草光合氮、磷利用率均与叶比重呈负相关关系。

关键词: 荧光特性, 放牧干扰, 光合特性, 狼针草, 水分关系

Abstract:

Aims Our objective was to evaluate (a) the impact of livestock grazing disturbance on physiological traits of Stipa baicalensis and (b) the adaptive mechanisms that S. baicalensis employed.
Methods We investigated the diurnal variations of photosynthetic characteristics, water relations, light energy utilization, photosynthetic apparatus activity and osmotic regulation of S. baicalensis growing in both grazing and enclosed grassland of Hulun Buir, Inner Mongolia.
Important findings Both ribulose-1,5-bisphosphate carboxylase (RUBPCase) and chlorophyll content increased and the direction of electronic chain was altered with grazing, which is beneficial for S. baicalensis to cope with the impact of grazing disturbance by accumulating more assimilates. The midday depression of photosynthesis of S. baicalensis in the enclosed grassland resulted from the decline of RUBPCase carboxylation capacity, which is due to the absence of P. The photochemical quenching (qP) of S. baicalensis in the grazed grassland is higher, which reflects that it tended to use more absorbed solar energy to improve photosynthetic capacity, which was adaptive to the effects of grazing. Lower leaf water content of S. baicalensis in the grazed field led to the increase of osmotic regulating substances for obtaining sufficient water from the soil. In addition, grazing disturbance promoted the absorption and utilization of N by S. baicalensis. Negative correlation of leaf mass per area (LAM) with photosynthetic nitrogen-use efficiency (PNUE) and photosynthetic phosphorus-use efficiency (PPNE) was observed in the S. baicalensis in both grasslands. Our research demonstrated that various ecophysiological mechanisms were employed by S. baicalensis as adaptive to grazing.

Key words: fluorescence characteristics, grazing disturbance, photosynthetic characteristics, Stipa baicalensis, water relation