%0 Journal Article
%T Photosynthetic characteristics of Nitraria tangutorum and Haloxylon ammodendron in the ecotone between oasis and desert in Minqin, Region, Country<br>民勤绿洲荒漠过渡带植物白刺和梭梭光合特性
%A ZHAO Changming
%A WEI Xiaoping
%A WEI Qiushi
%A DENG Jianming
%A CHENG Dongliang
%A WANG Genxuan
%A <br>赵长明
%A 魏小平
%A 尉秋实
%A 邓建明
%A 程栋梁
%A 王根轩
%J 生态学报
%D 2005
%I 
%X Nitraria tangutorum and Haloxylon ammodendron are dominate the ecotone between oasis and desert in Minqin. The artificial H. ammodendron communities have degenerated where the water table declined after heavy pumping of the groundwater for agriculture. The diurnal variations of gas exchange and chlorophyll fluorescence of green branches in H. ammodendron and leaves of N. tangutorum were investigated in the ecotone. Net photosynthetic rate (P_n), Transpiration rate (E), water use efficiency (WUE) and predawn photochemical efficiency of PSII (F_v/F_m) in H. ammodendron were lower than in the leaves of N. tangutorum, while both species showed midday photosynthetic depression. Stomatal limitations (L_s), intercellular CO_2 concentration (C_i) and F_v/F_m showed that the midday (9:00 to 12:00) photosynthetic depression in H. ammodendron was predominantly due to stomatal limitation. By contrast, afternoon (12:00 to 15:00) depression of P_n was caused by non-stomatal limitation, namely, photoinhibition. Photosynthetic depression of N. tangutorum was predominantly due to stomatal limitation at all periods of the day. The temperatures of assimilating branches (T_(leaf)) of H. ammodendron were higher than the air temperatures (T_(air)) especially at noon, while the T_(leaf) of N. tangutorum were lower than T_(air). So the assimilating branches of H. ammodendron not only suffered from the drought and strong-light stress but also from the rigorous high temperature stress compared with N. tangutorum at noon. In conclusion, the results of physiological research on photosynthesis suggested that the N. tangutorum adapt to the environmental conditions of the ecotone between oasis and desert more than H. ammodendron, and this may be one of the important reasons of why the artificial N. tangutorum communities in the ecotone between oasis and desert degenerated.
%K Haloxylon ammodendron
%K Nitraria tangutorum
%K ecotone
%K stomatal limitation
%K photoinhibition<br>梭梭
%K 白刺
%K 过渡带
%K 气孔限制
%K 光抑制
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=90BA3D13E7F3BC869AC96FB3DA594E3FE34FBF7B8BC0E591&jid=FE163E5DB2274E5937319DE98913EC37&aid=BDAC194AC34804CC&yid=2DD7160C83D0ACED&vid=C5154311167311FE&iid=5D311CA918CA9A03&sid=3243429ECEACC611&eid=B7C453D138C8DFC1&journal_id=1000-0933&journal_name=生态学报&referenced_num=13&reference_num=37