Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠植物梭梭和沙拐枣光合作用及水分利用效率研究 | |
| 其他题名 | Studies on Photosynthesis and Water Use Efficiency of Desert Plants |
苏培玺
| |
| 出版年 | 2003 |
| 学位类型 | 博士 |
| 导师 | 刘新民 |
| 学位授予单位 | 中国科学院寒区旱区环境与工程研究所 |
| 中文摘要 | 我国荒漠地区广泛分布的梭梭（Haloxylon ammodendron（C.A.Mey）Bge．）和沙拐枣（Calligonum mongolicum Turcz．）及其同属的其它种类，是我国干旱区的重要植被组分，在很多地方为优势种群。虽然国际上有关于分布于前苏联和蒙古等地区的梭梭和沙拐枣有C_4途径特征的报道，但学术界仍然有争论，对于广泛分布于我国的这两个属的植物至今尚无有关光合途径方面的深入研究。此项研究的目的在于探索这两种荒漠植物的光合作用结构与光合作用的生理学特性，并为保护和恢复荒漠地区自然生态系统，维护荒漠绿洲防护体系的稳定性，开展抗逆植物种及品种的选育，提供理论依据。同时还对柠条、花棒、泡泡刺和红沙等荒漠植物，以及绿洲作物玉米，棉花等进行了比较研究。结果表明，梭梭和沙拐枣都具有花环结构（Kranzanatomy），同化枝的613c值分别为-14.3％0和-14.8%，CO_2补偿点分别为1.6和4.3μmol mol~(-1)，光饱和点分别为1660.0和1755.6μmol·m~(-2)·s~(-1)，证实了分布于我国的这2种木本植物均具有明显的C_4光合特征。其光合途径不因生长季节和水分条件的变化而改变。在雨后湿润条件下光补偿点降低而光饱和点升高，光能利用率显著提高。柠条（CaraganakorshinsiKom.）、泡泡刺（Ni traria sphaerocarra Maxim．）、花棒（Hedysarum sc即ariu水Fisch．et Mey）和红沙（Reaumuria soongorica（Pall.）Maxim．）叶片的δ~(13)C值分别为-25.8‰、-25.8‰、-26.4‰和-28.1‰；沙枣和胡杨分别为-28.1％0和-29.7％，柠条、泡泡刺、花棒和红沙等荒漠植物，以及沙枣和胡杨等为C_3植物。在荒漠干燥环境下，梭梭和沙拐枣的光合速率日进程呈非典型双峰型，其最大净光合速率（Pn）分别达到36．22和48.34μmol CO_2·m~(-2)·s~(-1)，8:00-18:00时日平均Pn分别为18.O3和25.38μmol CO2·m-2 s-1。梭梭和沙拐枣的水分利用效率（WUE）日均值分别为1.72和1.31 mmol CO_2·mol~(-1)H_2O，最大值分别为2.63和2.16 nunolCO_2·mol~(-1)H_2O。而柠条WUE的日均值和最大值分别只有0.70和1.42mmolCO_2·mol~(-1)H_2O。梭梭和沙拐枣在雨后湿润状况时（空气相对湿度高出干燥状况时1倍），Pn日变化呈单峰型，没有强光时的光合下调，二者的峰值都比荒漠干燥条件下推后Zh出现，光合速率高于干燥时的值，日进程中最高Pn梭梭和沙拐枣分别高出2.8和3.8件molCO_2·m~(-2)·s~(-1)，最高WUE分别在5和mmolCO_2·mol~(-1)H_2O以上，为干燥时的2倍。从梭梭和沙拐枣气体交换的季节变化得出，9月份二者的净光合速率最高，水分利用效率最大，水分利用效率的高低变化与降水量的高低分布相一致。在荒漠干燥环境下，梭梭在15:00出现明显的光合下降，沙拐枣在14:00出现光合下降，与之相对应的时间各自的胞间CO_2浓度都升高，而气孔限制值降低。说明造成梭梭和沙拐枣光合下降的原因为非气孔因素。通过测定梭梭和沙拐枣的叶绿素荧光参数得出，梭梭的光系统II光化学效率在15:00-16:00最低，与其光合下降对应；沙拐枣在14:00左右最低，此时其净光合速率也出现最低，表明这一阶段各自的光系统II光化学反应受到抑制；从它们各自在最低净光合速率之后出现次高峰，以及光系统II光化学效率的稳定缓慢增高可以看出，这种抑制很快消失。在湿润条件下梭梭和沙拐枣没有光抑制现象，光合速率最高值均推后出现，证明引起梭梭和沙拐枣光抑制现象的原因是水分胁迫。光抑制现象可能是梭梭和沙拐枣适应荒漠环境的主动调节。研究结果还表明，荒漠植物月水分利用效率与年平均水分利用效率的相关性在8月份最高，其方程式为：WUE_年＝-1.8＋1.98 WUE_月（P=0.011，r=0.96）。月碳同位素比率（~(13)C／~(12)C）与年平均WUE的相关性在8月和9月最大，可靠性最高，其方程式为：WUE_年：4.7＋0.08 ~(13)C／~(12)C月（P＝0.057，r=0.87）。用稳定碳同位素比率指示温带荒漠植物的短期水分利用效率，随着叶片或同化枝成熟，越往生长后期，正相关性越大，直至霜降；用稳定碳同位素比率指示植物的长期水分利用效率，以8月下旬至9月下旬采样最好。几种荒漠植物长期水分利用效率的排列顺序为：梭梭＞沙拐枣＞柠条＞花棒铝泡泡刺＞红沙。 |
| 英文摘要 | H. ammodendron, C. mongolicum and other species of the same genera are widely distributed over the desert regions of China. They are important component of the desert vegetation or even as its dominant population in China's arid zones. Although it had been reported in some international academic journals that the desert plants Haloxylon ammodendron and Calligonum mongolicum were identified possessing some characteristics of C4photosyntheticpathway, some problems is still in dispute. In addition, few researches have reached the systematic study on the photosynthetic characteristics of those two species distributed in China. Even no one has focused on their photosynthetic pathway so far. The purpose of this research is to probe into the photosynthetic structure of assimilating organs and physiological characteristics of the photosynthesis in those two species, and to provide a theoretical basic of reference for protecting and restoring natural ecosystem of desert regions, maintaining the stability of protective system in the periphery district of oases, and breeding and selecting hardy species and improved varieties. At the same time, comparative studies on other desert plant species, such as Caragana korshinskii, Hedysarum scoparium, Nitraria sphaerocarpa and Reaumuria soongorica, and some oasis crops, such as corn and cotton, were also conducted. The paraffin cut sections of photosynthetic organs, i.e. assimilating shoots of H. ammodendron and C. mongolicum were examined and photographed with light microscopy; stable carbon isotopic ratios (δ~(13)C or ~(13)C/~(12)C) of leaves or assimilating shoots were analysed with MAT-252 mass spectrometer; photosynthetic gas exchanges were measured using LI-6400 Portable Photosynthesis System (LI-COR, Nebraska, USA). In addition, the chlorophyll fluorescence and their diurnal course were measured together with gas exchange by FMS-2 Fluorescence Monitoring System (Hansateck, UK). The results showed that both H. ammodendron and C. mongolicum have Kranz anatomy. The 5 ~(13)C value of assimilating shoots of H. ammodendron and C. mongolicum were -14.3 %a and -14.8%o, CO_2 compensation point 1.6 and 4.3μmol o mol~(-1), and light saturation point 1660.0 and 1755.6μmol o m~(-2) o s~(-1), respectively. Those proved that H. ammodendron and C. mongolicum distributed in China also belong to species of C_4 woody plants. Under moist condition after rain the light compensation point of H. ammodendron and C. mongolicum reduced, but their light saturation point rose, efficiency for solar energy utilization was significantly raised. Their photosynthetic pathway did not change as the growing season and water condition changed. Theδ~(13)C value of leaves for C. korshinskii, N. sphaerocarpa, H. scoparium and R. soongorica were -25.8%o, ~25.8%o, -26.4%o and -28.1%o respectively, while the corresponding values for Elaeagnus angustifolia and Populus euphratica were -28.1%o and -29.7%o respectively. Such desert plants as C. korshinskii, N. sphaerocarpa, H. scoparium and R. soongorica, and also E. angustifolia and P. euphratica were proved to be C_3 plants. Diurnal course of photosynthetic rates of H. ammodendron and C. mongolicum under the desert dry environment performed as a non-typical bimodal mode, with a maximum net photosynthetic rate (Pn) of 36.22 and 48.34 |amol CO_2 o m~(-2) o s~(-1) and a diurnal mean Pn (in \tthe period of 8 : 00-18 : 00) of 18.03 and 25.38μmol CO_2 o m~(-2) o s~(-1) respectively. Diurnal mean water use efficiency (WUE) of H. ammodendron and C. mongolicum were 1.72 and 1.31 mmol CO_2 o mol~(-1)H_2O, with maximum values of 2.63 and 2.16 mmol CO_2 o mol~(-1)H_2O respectively. The diurnal mean value and maximum value for C. korshinskii were only 0.70 and 1.42 mmol CO2 o mor'EbO respectively. Under the moist condition after rain (the air relative humidity was as twice as that under dry conditions) the diurnal course of Pn for H. ammodendron and C. mongolicum showed a unimodal mode, with no midday depressions of photosynthetic rate. The maximum Pn of H. ammodendron and C. mongolicum exceeded the values by 2.8 and 3.8μmol CO2 o m~(-2) o s~(-1) respectively. The occurrence of peak values of Pn for both plants was delayed by two hours in compared with dry conditions. WUE was also higher than that under dry conditions for them. The maximum WUE of if. ammodendron and C. mongolicum were higher by 5 and 4 mmol CO_2 o mol~(-1)H_2O respectively, about as twice as that under dry condition. Analysis of the seasonal change in gas exchange of H. ammodendron and C. mongolicum suggested that changes in WUE were consistent with the changes in precipitation, with the highest Pn and WUE occurred in September. In the desert dry environment H. ammodendron showed a depression of Pn at 15 : 00, and C. mongolicum at 14:00. At the same time, their intercellular CO_2 concentration (Ci) rose, and their stomatal limitation value (Ls) decreased. This suggested that the photosynthetic rate depression for H. ammodendron and C. mongolicum showed be attributed mainly to non-stomatic factors. Through the measurement of chlorophyll fluorescence parameters of H. ammodendron and C. mongolicum it was found that the photochemical efficiency of PS II for H. ammodendron reached its minimum between 15 : 00-16 : 00, and its net photosynthetic rate correspondingly declined, while the lowest value for C. mongolicum occurred at about 14 I 00, when its Pn was also lowest, suggesting that their photochemical reaction of PS II were inhibited. From the fact that a second peak occurred following the lowest Pn and a slow improvement in photochemical efficiency of PS Hit can be reasoning that such photoinhibition can be removed rapidly. However, no photoinhibition was observed for both H. ammodendron and C. mongolicum under moist condition after rain, and the occurrence of maximum Pn was delayed. This shows that the photoinhibition for H. ammodendron and C. mongolicum was caused by water stress. Photoinhibition is an active regulation mechanism of H. ammodendron and C. mongolicum to adapt the desert environment. The correlation analysis of monthly and yearly WUE of desert plants can be expressed as a formula WUE_(year) = -1.8 + 1.98 WUE_(month)(P = 0.011, r = 0.96). |
| 中文关键词 | 荒漠植物 ; 梭梭 ; 沙拐枣 ; 同化枝 ; C_4途径 ; 光合作用 ; 水分利用效率 ; 稳定碳同位素比率 ; 花环型结构 ; 光抑制 ; 光系统II |
| 英文关键词 | Desert plant Haloxylon ammodendron Calligonum mongolicum assimilating shoot C_4pathway photosynthesis Water use efficiency (WUEorPn/E) stable carbon isotope ratio (δ~(13)C or ~(13)C/~(12)C) Kranz anatomy photoinhibition PS II |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286320 |
| 推荐引用方式 GB/T 7714 | 苏培玺. 荒漠植物梭梭和沙拐枣光合作用及水分利用效率研究[D]. 中国科学院寒区旱区环境与工程研究所,2003. |
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