摘要
比较研究了 3种沙地灌木羊柴 (H edysarum fruticosum var.mongolicum)、油蒿 (Artemisia ordosia)和沙柳(Salix pasmmophylla)在适宜光照和温度 (春季 )以及高温强光 (炎热的夏季 )的光合气体交换特点。前两种灌木为自然分布的种类 ,后一种为人工插条栽植的种类。瞬时光合有效辐射 (PPFD)、叶面温度 (Tleaf)、净光合速率 (PN)、光系统 II最大量子产率 (Fv/ Fm)等参数每隔 2 h进行 1次测量。羊柴和油蒿分别比沙柳具有高的净光合速率 (PN)和气孔导度 (gs) ,在高叶温 (>46℃ )和强日辐射光 (PPFD>2 10 0 μm ol· m- 2· s- 1 )下这种差异更明显。在光合作用日进程中 ,净光合速率的下降主要受气孔开度的影响。沙柳的光合作用在高温条件下受到严重的抑制 ,表现在光合产物的负积累 (以呼吸消耗为主 ) ,炎热夏季沙柳的光合净积累仅在早上进行。沙柳的最大量子产率在 16∶ 0 0左右最低 ,表明这一阶段光系统 II受到抑制 ,但这种作用至晚间消失。在炎热夏季 ,荒漠灌木的光合作用日动态曲线表现出典型的双峰型 ,而在春季则为单峰型 ,且夏季的第一个峰值比春季的峰值早 2 h左右。实验表明高温造成了沙柳光合作用的严重抑制 ,而天然种类羊柴和油蒿则在相同的环境下更抗高温与强光辐射。沙柳在春季适宜的环境下积累?
Field studies of gas exchange and chlorophyll fluorescence of three desert shrub species,Hedysarum fruticosum var. mongolicum,Artemisia ordosia and Salix pasmmophylla, showed different patterns under different leaf temperature (T_ leaf) and incident photosynthetic photon flux density (PPFD) regimes. The leaves of both Hedysarum and Artemisia exhibited higher P_N and g_s than was observed in Salix, especially under the very high T_ leaf (>46 ℃) and high PPFD (>2100 μmol·m -2·s -1) of the hot summer period. An observed decrease in P_N through the course of the day was largely associated with stomatal closure. However,P_N of Salix leaves continued to be seriously depressed by high temperatures from midday through to evening,as shown by the negative P_N values in the hot summer period,and no such depression was observed in the spring. The maximal photochemical efficiency of PSII (F_v/F_m) of Salix was lowest at 16∶00,indicating the inhibition of PSII by heat. In summer,all three shrub species showed a pronounced midday depression in P_N and g_s,while in spring they showed a single-peaked response and the initial summer peak appeared 2 h earlier than the spring peak in all three species. High temperatures led to this difference in patterns of gas exchange and the serious depression of P_N in Salix. Our results clearly showed that Hedysarum and Artemisia were much more tolerant to heat and high irradiance than was Salix, which fixed most of its CO_2 during its spring fast growth stage. Nevertheless,in summer it had to survive severe hot stress through strong respiration,and the storage of CO_2 in the early morning.
出处
《植物生态学报》
CAS
CSCD
北大核心
2001年第5期525-531,共7页
Chinese Journal of Plant Ecology
基金
国家重大基础研究与发展计划项目 ( 973项目
G19980 10 10 0 )
中国科学院"九五"重大 B项目 ( K2 95 1-B1-10 8)
中国科学院重大创新项目 ( KSCX1-0 8-0 2 )
