Agpoyron trachyeaulun L., Elymus nutans Griseb, Bromus inermis Layss and Poa crymophila Keng were reseeded in fenced areas using no-tillage. Vegetation height, coverage and grass yield were studied in order to reveal the effects of different restoration measures for vegetation characters, underground biomass, seed bank and diversity of Amdo in a typical degraded meadow in Tibet. Results showed that vegetation height, coverage and grass yield improved after no-tillage reseeded and fenced. Plant diversities increased slightly while there were significant differences among dominant species. Further, changes were seen in underground biomass of plant communities. Biomass of 0~10 cm soil layer ascended dramatically after fenced and reseeded. Additionally, the numbers of seeds in both fenced and reseeded plots were greater outside the fence and distributed mainly within 0~5 cm soil layer.

为探讨不同恢复措施条件对草地植被特征、地下生物量、地下种子库以及多样性等方面的影响,在西藏安多典型退化草地进行围栏,并选用细茎冰草( Agpoyron trachyeaulun L.)、垂穗披碱草( Elymus nutans Griseb)、无芒雀麦( Bromus inermis Layss)和冷地早熟禾( Poa crymophila Keng)4种牧草,在围栏内进行免耕补播的试验研究。结果表明:经过免耕补播和围栏封育后,草地植物高度、盖度、产量均有不同程度的提高;植物多样性有少量增加,植被优势种差异较显著;植物群落地下生物量变化幅度较大,特别是经过围栏和补播的草地,其0~10 cm地下生物量增加明显;此外,土壤种子库测定表明,围栏和补播试验地种子总数明显高于围栏外,增加的种子数主要分布在0~5 cm的土层中。

Grassland is one of China’s most significant land resources and as such it directly affects the country’s economic development and ecological sustainability. The appropriate development of grass-based industry is an important way to maintain environmental safety, promote the structural adjustment of agriculture and increase farmers’ income. In this paper, grass-based industry is considered according to its developmental status, with the industry accordingly divided into a series of three linked parts: prenatal, production and postnatal. Grass-based industries have great potential to further develop the linkages between these three developmental stages. Based on the principle of the harmonious development of economic and environmental factors, grass production methods and management models must be changed as soon as possible to realize this potential. Government and enterprises should cooperate with each other to improve the markets for grass-based products. Learning from the experience of more developed countries, China should establish a grass-based industry code in the classification of national economic activities. Furthermore, improved legislation is needed to determine the ownership of grasslands and to regulate the industry they support.

草地资源是我国最重要的国土资源之一,充分合理的利用这种资源禀赋,直接关系着我国经济的发展与生态环境的可持续。草业经济的发展在国民经济中,具有维护生态安全,推动农业产业结构调整和增加农民收入的重要意义。本文在对我国草业经济发展现状进行简述的基础上,将草产业的运行按照产业链的产前、产中、产后环节进行划分,在每一环节中分别将国内外草业经济发展进行对比,结果表明,在产品生产环节、企业组织与产品加工环节和市场及配套环节中,我国草产业发展都还具有很大的提升空间。为了充分发挥我国草地资源的发展潜力,在坚持经济发展与环境相协调这一指导原则的基础上,需要尽快进行草业生产方式和经营形式的变革,由政府与企业相互配合,完善草产品市场的运作机制,尽快设立草业行业在国民经济中的行业代码,并学习发达国家的先进经验,完善草原立法,将草原立法的出发点由确定所有权转移到指导和规范草产业的运行上来。

Grassland degradation had characteristic of vegetation and soil degradation synchronization. In order to study the relationships between community biomass and soil nutrient during degradation processes in the northern Tibet grassland, alpine grassland in Nagqu, northern Tibet with different degraded degrees were selected to study the variations of soil nutrients and above ground biomass. The results showed that with increasing of grassland degradation, aboveground biomass and soil organic matter significantly decreased. Total nitrogen, total phosphorus and total potassium had significant positive correlation with soil organic matter ( P <0.05) whereas soil pH had significant negative correlation with soil organic matter content ( P <0.05). Aboveground biomass had significant positive correlation with soil organic matter content ( P <0.05) but had no correlation with total nitrogen, total phosphorus, total potassium and pH ( P >0.05).

草地退化会呈现出地上群落与土壤的同步退化,相对于地上植被的退化,土壤退化呈现一定的滞后性,为分析藏北高寒草地退化过程中的群落地上生物量与土壤养分关系,选取那曲地区不同退化程度高寒草地,对土壤养分和地上生物量进行研究。结果表明,随着退化程度的加剧,藏北地区退化草地群落地上生物量和土壤养分(除全钾外)总体上表现为降低趋势,而且步调基本一致。土壤全氮、全钾含量与土壤有机质呈显著正相关( P <0.05),土壤pH与有机质含量呈显著负相关( P <0.05)。草地地上生物量与土壤有机质含量呈显著正相关( P <0.05),与全氮、全磷、全钾含量的相关性不显著( P >0.05)。

In order to screencold tolerant Elymus germplasm, the 21 days aged seedlings of three Elymus species from Tibet were used to investigate the physiological, biochemical responses and resistanceunder different low temperature treatments(18, 10, 5, 0 ℃) with 18 ℃ as check.With the increase of low temperature stress Elymus sibiricus cv. Tongde had maximum relative membrane permeability, but Baqing ( E. nutans ) is the minimum. The contents of chlorophyll in Baqing showed a trend of rising first then falling, but the content of Chlorophyll in Tongde and Naqu ( E. nutans ) increased significantly ( P <0.05). The soluble protein content in Baqing had the smallest increase and it only increased 2.59 times when compared with control; The soluble protein content in Tongde and Naqu increased significantly ( P <0.05), and they increased 5.31 times than the control. The soluble sugar content in Baqing and Tongde showed a trend of rising first and then falling, but the soluble sugar content in Naqu increased significantly ( P <0.05) and it is 2.14 times of the control. The MDA content in Tongde had the biggest increase; the MDA content in Baqing decreased significantly at 0 ℃ when compared with that at 5 ℃( P <0.05). The free proline in all materials tested increased.Tongde had the maximum Pro content, and it increased 2.58 times when compared with control; Baqing had the minimum Pro content, it only increased 1.44 times when compared with control. The superoxide dismutase activities of Baqing showed a trend of rising first then falling. But the superoxide dismutase activities of Naqu increased significantly ( P <0.05) and it is 1.65 times of control. The peroxidase activities in Naqu is the maximum and it increased 4.13 times when compared with control; The peroxidase activities in Tongde is the maximum and it is 2.19 times of control. Membership function analysis showed the order of cold resistance of three Elymus species: Baqing>Tongde>Naqu.

探讨低温胁迫下西藏野生披碱草( Elymus )苗期抗寒性及其生理变化,可为优良牧草选育提供理论依据。以披碱草属3个牧草为试验材料,出苗21 d后在人工气候箱内进行低温胁迫,设18、10、5和0 ℃共4个低温处理,其中以18 ℃为对照。结果表明,随着低温胁迫的加剧,相对膜透性,同德老芒麦( E. sibiricus cv. Tong De)的增幅最大,巴青垂穗披碱草( E. nutans )增幅最小。叶绿素含量,巴青垂穗披碱草先升高后降低,同德老芒麦与那曲垂穗披碱草显著升高( P <0.05)。巴青垂穗披碱草可溶性蛋白(SP)含量增加幅度最小,为对照的2.59倍;同德老芒麦与那曲垂穗披碱草SP含量显著上升( P <0.05),均为对照的5.31倍。巴青垂穗披碱草与同德老芒麦的可溶性糖(SS)含量先升高后降低,而那曲垂穗披碱草SS含量显著增大( P <0.05),为对照的2.14倍。同德老芒麦的丙二醛(MDA)含量增幅最大,巴青垂穗披碱草MDA含量0 ℃较5 ℃时显著降低( P <0.05)。3种供试材料游离脯氨酸(Pro)含量均升高,同德老芒麦增幅最大,为对照的2.58倍;巴青垂穗披碱草最小,为对照的1.44倍。巴青垂穗披碱草超氧化物歧化酶(SOD)活性先增强后减弱,那曲垂穗披碱草SOD活性显著增强( P <0.05),为对照的1.65倍。那曲垂穗披碱草过氧化物酶(POD)活性上升幅度最大,为对照的4.13倍;同德老芒麦最小,为对照的2.91倍。隶属函数法综合评价表明,3种野生披碱草的抗寒性依次为巴青县野生垂穗披碱草>同德老芒麦>那曲县野生垂穗披碱草。

The Qinghai-Tibet Plateau is considered to be ideal region for studying the response of natural ecosystems to climate change because its’ mountainous environments is one of the most fragile of the global ecosystems. The impacts of the changes in temperature and precipitation on the phenology varied among different grasslands. After experiencing a distinct warming in recent decades, some studies noted that remarkable variations in vegetation in the Qinghai-Tibet Plateau were potentially due to climate change. In order to determine the impacts of climate change on vegetation phenology and potential productivity, this paper used meteorological data during 1965–2013 in the Qinghai-Tibet Plateau (e.g., monthly temperature, precipitation and sunshine duration) of 107 meteorological stations, and extracted vegetation phenological indices using MODIS-derived normalized difference vegetation index data during 2000–2013, and used the Thornthwaite Memorial model and GIS techniques to analyze the spatial and temporal trends of potential climate-driven forage productivity in the Qinghai-Tibet Plateau. Then by analyzing 22 years of continuous observation data of growth stages of forage in the Qinghai-Tibet Plateau, the relationship between meteorological factors and major growth stages of forage was determined. Also the driving factors of the dynamics of potential climate productivity in the Qinghai-Tibet Plateau were determined. Furthermore, the relationship between temperature or precipitation and sunshine duration during forage growth period was determined based on regression analysis. The results showed that the potential climate productivity of forage in the Qinghai-Tibet Plateau was consistently varied with geographical region and spatial temperature distribution. Average temperature in the Qinghai-Tibet Plateau rose during the nearly 50-year period, increasing by 0.53 ℃(10a)1. Precipitation generally increased at the rate of 7.81 mm(10a)1, while sunshine duration decreased by 16.94 h(10a)1. Potential climate productivity of forage in the Qinghai-Tibet Plateau presented an increasing trend from 1965 to 2013, and spatial changes of the productivity, in turn, increased from northwest to southeast. Then potential climate productivity of forage in the north and south in the plateau significantly increased and there was less variation in the east of the plateau. Furthermore, the regreening, heading and blossoming of forages advanced, while yellowing and withering delayed year after year, which extended the forages phenological phases. Regreening stage of forage delayed from southeast to northwest, although withering stage showed no obvious change. Under drier and warmer conditions, phenological periods of grassland vegetation in the region became closely related to climate change. Then precipitation and sunshine duration were negatively correlated with phenological period of the grassland vegetation. Temperature was the dominant constraint on phenological phases of grassland vegetation in the study area. The study formed a relevant reference and basis for the protection of grassland ecosystems and enhancing potential climate productivity in Qinghai-Tibet Plateau.

基于青藏高原及周边107个气象站点1965—2013年逐月气温、降水及日照时数等气象数据, 分析了1965年以来青藏高原区的气候变化趋势, 并采用MODIS数据、Thornthwaite Memorial模型及GIS技术分析了近50 a青藏高原牧草气候生产潜力及其时空变化特征; 利用连续22 a的青藏高原牧草生育期观测数据, 探讨了牧草生育期的时空变化特征及气象因子与牧草主要发育期的关系。结果表明: 1)近50 a青藏高原平均气温呈上升趋势, 升温幅度达0.53 ℃(10a)1, 降水量总体呈现上升趋势, 但增加幅度较小, 其倾向率为7.81 mm(10a)1; 而日照时数呈下降趋势, 其下降幅度为16.94 h(10a)1。2)1965—2013年青藏高原牧草气候生产潜力总体呈增加趋势, 在空间上, 由西北向东南依次增加, 青海省北部及南部部分地区气候生产潜力上升幅度较大, 而西藏东部上升幅度较小, 且南北部地区差异较大。3)牧草返青期、抽穗期及开花期均呈提前趋势, 而黄枯期呈现推迟趋势, 从而延长了牧草物候期; 由东南向西北牧草返青期逐渐推迟, 而黄枯期主要出现在一年中的第257~289 d, 其空间整体差异不如返青期明显。4)温度和降水均与牧草物候期呈显著正相关, 而日照时数与其呈显著负相关, 且温度是影响牧草物候期变化的主要因子。利用青藏高原牧草生产潜力及物候期与气候因子的响应规律, 可为提高该区牧草的实际产量和保护青藏高原草地生态系统提供借鉴和依据。

为探讨不同垂穗披碱草居群产量和营养品质状况，本研究分析评价了４５个垂穗披碱草居群的产量性状和粗蛋白质（ＣＰ）、可溶性糖（ＷＳＣ）、中性洗涤纤维（ＮＤＦ）、酸性洗涤纤维（ＡＤＦ）４个品质性状。结果显示，居群间产量、ＣＰ、ＷＳＣ、ＮＤＦ和ＡＤＦ含量存在极显著差异，４５个垂穗披碱草居群的产量性状和品质性状近似正态分布，其变化范围为２０６２．５９～１８５９７．７３ｋｇ／ｈｍ ２ （鲜草产量），５２９．４２～４６８２．６０ｋｇ／ｈｍ ２ （干草产量），１３．８８％～２３．９２％（ＣＰ），１．５９％～６．０３％ （ＷＳＣ），５７．３４％～６４．９７％（ＮＤＦ）和３５．０６％～４７．２３％（ＡＤＦ）。各性状变异程度不同，产量性状变异均达６２％以上，品质性状中ＷＳＣ 变异系数最大，达３１．１９％。相关分析表明，ＣＰ 与ＮＤＦ 和ＡＤＦ 含量呈极显著负相关，ＡＤＦ与ＮＤＦ含量呈显著正相关，ＷＳＣ 含量与ＮＤＦ 含量呈极显著正相关，与产量和ＡＤＦ 呈显著负相关。根据各性状的相关关系，筛选出５个ＣＰ和ＷＳＣ 含量高而ＮＤＦ和ＡＤＦ含量低的垂穗披碱草居群。

The genetic diversity of 52 E. sibiricus accessions were evaluated by SSR markers. A total of 318 fragments were identified with 18 SSR primers sets, of which 204 (86.48% ) were polymorphic, and each primer generated 13.1 fragments, the polymorphism information content (PIC) per primer was 0.267~0.471, with an average of 0.35, and the marker index (MI) of SSR was 3.98. The genetic similarity (GS) coefficient of the tested accessions ranged from 0.622 to 0.895, with an average of 0.766. The Nei’s index of diversity (He) of the 52 accessions was 0.3286, and the Shannon’s index (Ho) was 0.4851. These results suggested that there was rich genetic diversity among the tested wild resources of E. sibiricus. 52 accessions could be divided into five main groups by cluster and principal component analysis, the accessions from the same region or with the same habitat type tends to were classified into the same group, indicating the geographical distribution of genetic diversity of E. sibiricus.

利用SSR标记技术对来自青藏高原的52份老芒麦（Elymus sibiricus L）材料的遗传变异及亲缘关系进行了研究。18对SSR引物共扩增出236条清晰的条带，其中多态性条带204条，多态性位点率（PPB）为86.44%，每对引物扩增出7~20条带纹，平均为13.1条，多态性信息（PIC）含量为0.267~0.471之间，平均为0.35，SSR标记效率（MI）为3.98；材料间的遗传相似系数（GS）为0.622到0.895之间，平均GS值为0.766，52份种质的Nei’s 遗传多样性指数（He）为0.3286，Shannon指数（Ho）为0.4851，表明供试材料之间差异明显，具有较为丰富的遗传多样性。根据研究结果进行聚类分析，可将52份老芒麦材料分成5大类，具有相同地理来源或相似生境的材料趋向于聚为一类。

Drought resistance of four native grass species, including Roegneria thoroldiana, Poa pratensis, Elymus nutans and Festuca sinensis, in seedling stage was studied by pot culturing experiment. The results indicated that, the content of free proline(Fpro), soluble protein and soluble sugar, and the activity of catalase(CAT) and peroxidase(POD) increased with the increasing of drought stress. Beside, with the increasing of drought stress, decompose of chlorophyll, membrane permeability and electrolyte leakage rate were also increased, and the cellular tissues of grasses were damaged. Different grass spices had different changes on physiological and biochemical indexes under drought stress. The results of subordinate function analysis indicated that, the drought resistance ability of four grass species were R.thoroldiana>P.pratensis>E.nutans>F.sinensis.

采用盆栽法对梭罗草（Roegneria thoroldiana）、草地早熟禾（Poa pratensis）、垂穗披碱草（Elymus nutans）和中华羊茅（Festuca sinensis）4种高原乡土禾本科牧草幼苗的抗旱性进行了比较。结果表明，一定程度的干旱胁迫后，4种禾草的游离脯氨酸含量、可溶性蛋白含量、可溶性糖含量、过氧化氢酶活性、过氧化物酶活性等均有所增加，且叶绿素分解、细胞膜透性增大、电解质外渗率增加，牧草组织细胞受到伤害。不同牧草在干旱胁迫下生理生化指标的变化不同，综合各项指标，运用隶属函数分析表明，4种禾草抗旱性强弱的排序为梭罗草>草地早熟禾>垂穗披碱草>中华羊茅。

In order to selected the cold resistance germplasm of Poa , the physiological, biochemical responses and resistances of nine wild Poa germplasms in Gangsu province were investigated under different low temperature treatments (5, 0, -5, -10℃). The results showed that the relative membrane permeability in the leaves, the contents of free proline (Pro), soluble sugar (SS), soluble protein (SP) and malondialdehyde (MDA), superoxide dismutase (SOD)and peroxidase (POD)activities of nine wild Poa seedlings gradually increased with the temperature decreasing. Membership function analyses showed that P. annua had the strongest cold resistance, followed by P. micrandra , P. pratensis (Tianzhu) and P. pratensis (Gannan). P. poophagorum , P. sphondylodes , P. pratensis (Sunan), P. pratensis (Weiyuan) and P. pratensis (Xinglongshan) had the weakest cold resistance. Correlation analyses demonstrated that integrated assessment value of cold resistance had significant positive correlation with the content of soluble protein ( P P Poa .

以甘肃省境内采集的9个野生早熟禾（ Poa ）为试验材料，设5，0，-5，-10℃共4个温度处理，探讨其对低温胁迫的生理响应和抗寒性，为抗寒早熟禾种质材料筛选和新品种选育提供依据。结果表明：随着温度下降，各材料的叶片相对膜透性逐渐增大，游离脯氨酸（Pro）、可溶性糖（SS）、可溶性蛋白（SP）、丙二醛（MDA）含量逐渐增加，超氧化物歧化酶（SOD）和过氧化物酶（POD）活性逐渐增强。运用隶属函数法综合评价9个材料苗期抗寒性发现，一年生早熟禾（ P. annua ）抗寒性最强，小药早熟禾（ P. micrandra ）、草地早熟禾（天祝）（ P. pratensis ）和草地早熟禾（甘南）抗寒性中等；硬质早熟禾（ P. sphondylodes ）、波伐早熟禾（ P. poophagorum ）、草地早熟禾（肃南）、草地早熟禾 （渭源）、草地早熟禾（兴隆山）抗寒性弱。相关性分析表明，SP含量与抗寒综合评价值极显著正相关（ P P <0.05），Pro含量、SS含量、SOD活性、海拔与抗寒综合评价值成正相关，相对膜透性、MDA含量和年均温与抗寒综合评价值成负相关。

Abstract:This paper studies the different stages of corn through the application of GreenSeeker determine different varieties of corn under different nitrogen Normalized Difference Vegetation Index and the changes of leaf chlorophyll content and their relevance.The results showed that the chlorophyll content of corn at different period and the NDVI values are different,chlorophyll content and NDVI values are increased with the amount of nitrogen,the maximum fertilizer increase large,chlorophyll increase of 33%,NDVI increase of 7.25%,the chlorophyll and NDVI showed a significant positive correlation.The different varieties of corn increase different,Zhengdan 958 and Jinong 302 are better than Nongda 588.

摘要: 本文研究了玉米不同时期通过应用GreenSeeker 测定不同品种的玉米在不同施氮条件下归一化差值植被指数(NDVI)与叶片叶绿素含量的变化及其相关性。研究结果表明：不同时期玉米叶绿素含量与NDVI值是不同的，叶绿素含量和 NDVI值均随施氮量的增加而增大，其中最大施肥量增幅较大，叶绿素最大增幅为33%，NDVI最大增幅为7.25%，且叶绿素与NDVI呈显著正相关。不同的玉米品种增幅也不同，郑单958，吉农302要好于农大588。

To compare the drought resistance of bluegrass seedlings,the 14 varieties of Kentucky bluegrass seed were sowing after disinfection in the plastic pots,then thinned after emergence and fixed strains at 2 to 3 true leaf,left 15 uniform growth and distribution plants in every pot and regularly watering to ensure the normal growth of the seedlings. Drought stress trails were identified at 2 to 3 true leaf period by adding the PEG-6000 according to the Michel formula which are: 0 MPa (control),-0.3,-0.6,-0.9,-1.2 MPa in the study. Then supplement water every two days to maintain the concentration. Two groups of drought treatment and control (normal watering) were set to simulate drought stress of 14 bluegrass cultivars and four replications were set by treatment. The physiological and biochemical index,such as chlorophyll (CHL),malondialdehyde (MDA) content,proline (Pro) content,peroxidase (POD) and superoxide dismutase (SOD) activity were measured and analyzed. The content of CHL was decreased; and the content of the Pro,MDA and SOD showed upward trend; the POD activity increased at first and then decreased and finally increase again in the bluegrass seedlings; Drought resistance of 14 bluegrass varieties were obtained by subordinate function the order is: The No.3 Storpy>No.10 Narrow leaf bluegrass>No.1 Meri>No.2 Geronimoi=No.9 Blue apphire>No.7 Kentucky bluegrass>No.11 Kentucky bluegrass>No.4 Kentucky bluegrass>No.5 Wabash>No.8 Bluegrass=No.13 Kentucky>No.14 Kentucky bluegrass>No.6 Monopoly=No.12 Fylking.

为鉴定评价早熟禾幼苗抗旱性,将14个早熟禾品种的种子经消毒后播种在塑料花盆中,出苗后间苗,2~3个真叶定株,每盆留生长一致、分布均匀的幼苗15株,定期浇水,以保证幼苗的正常生长。待生长到3~4个真叶时进行干旱处理,依据Michel公式计算不同水势所需的PEG-6000的量,然后加入PEG-6000溶液进行干旱处理,处理的水势梯度为0 MPa(即为对照),-0.3,-0.6,-0.9和-1.2 MPa。处理后每2 d进行称重补水以维持溶液浓度。设干旱处理与对照(正常浇水)两组,对14个早熟禾品种幼苗进行模拟干旱胁迫,4次重复。测定叶绿素(CHL)含量、丙二醛(MDA)含量、脯氨酸(Pro)含量、过氧化物酶(POD)以及超氧化物歧化酶(SOD)活性等生理生化指标。结果表明,随着干旱胁迫的加剧,早熟禾幼苗叶片CHL含量呈下降趋势;Pro含量、MDA含量、SOD活性总体呈上升趋势;POD活性总体呈先降再升后降的趋势;利用隶属函数分析得出14个早熟禾品种的抗旱性强弱顺序依次为:3号恩托佩草地早熟禾>10号细叶早熟禾>1号优异草地早熟禾>2号斗士草地早熟禾=9号蓝钻草地早熟禾>7号草地早熟禾>11号草地早熟禾>4号草地早熟禾>5号瓦巴斯草地早熟禾>8号早熟禾=13号肯塔基草地早熟禾>14号草地早熟禾>6号莫诺波利草地早熟禾=12号菲尔津草地早熟禾。

In order to broaden the application range of reclaimed water in urban greenbelt, a pot experiment was conducted, reclaimed water was used in greenbelt irrigation test of white clover and alfalfa. The changes of photosynthetic characteristic and chlorophyll content under reclaimed water irrigation have been studied. The results showed that reclaimed water irrigation can improve photosynthetic indices in a certain period of time and to some extent. Later, reclaimed water for white clover irrigation, the photosynthetic rate (P n ), transpiration rate (T r ), conductance to H 2 O (G s ) and CO 2 concentration (C i ) under the irrigation test is significantly higher than that under running water irrigation. Two plants species’ changes of T r , P n , intercellular C i are closely related with G s . There is no significant difference in photochemical efficiency (F v /F m ) and chlorophyll content between running water and reclaimed water. In short, reclaimed water irrigation does not cause damage to white clover and alfalfa, and has a certain role in promotion.

为拓宽再生水在城市绿地灌溉中的应用范围,采用盆栽试验,通过对白三叶( Trifolium repens)和紫花苜蓿(Medicago sativa )主要光合指标及叶绿素含量的测定,研究了再生水灌溉对这两种常见绿地植物的影响。结果表明,再生水灌溉下白三叶和紫花苜蓿各光合指标在一定时期均不同程度优于自来水灌溉,再生水灌溉后期白三叶净光合速率(P n )、蒸腾速率(T r )、气孔导度(G s )和胞间CO 2 浓度(C i )显著高于自来水灌溉,两种植物T r 、P n 、C i 的变化与G s 密切相关;再生水灌溉对两种绿地植物的荧光参数(F v /F m )和叶绿素含量的影响与自来水灌溉相比差异不显著。由此可见,再生水对白三叶和紫花苜蓿的生长未造成胁迫,且有一定的促进作用。

During adaptation to the environment, plants can gradually develop drought resistance via a process of natural selection. Plants are often under water stress in the cold and dry environmental conditions on the Tibetan Plateau, and these conditions can directly affect various physiological activities. The aim of this study was to analyze and evaluate the drought resistance of selected plants from the Tibetan Plateau, and to provide a reference for selecting drought-tolerant plants. We collected six species of plants from the Tibetan Plateau; Hedysarum multijugum Maxim, Comarum salesovianum (Steph.) Asch. et Graebn., Berberis diaphana Maxim., Sibiraea laevigata (Linn.) Maxim., Caragana arborescens (Amm.) Lam. and Sophora moorcroftiana Benth Baker. To protect themselves against drought and low-temperature stress, plants have evolved efficient antioxidant systems to scavenge reactive oxygen species. We evaluated changes in the amounts of malondialdehyde (MDA), proline, soluble protein, chlorophyll, soluble sugars, and starch in leaves of these species subjected to increasingly severe drought conditions in a pot experiment. The soil moisture was greater than 80% of field capacity for the normal level, 50%-70% for mild drought, 30%-50% for moderate drought, and less than 30% for severe drought. In all six plant species, the MDA content increased slowly from day 0 to day 12 of the drought treatment, and then increased significantly after day 16 to reach a peak when the soil water content was approximately 12%. Caragana arborescens showed the smallest increase in MDA content under drought, but had the highest MDA content (4.72 mmol/g) among the six plant species. The proline content increased in all six species under drought, and there were significant differences among species in the amount of proline accumulated. The largest increase in proline content was in S. moorcroftiana (peak value, 9981.67 mg/g; 37.43 times that in CK), and the smallest was in S. laevigata (peak value was 0.49 times that in CK). The leaf soluble protein content increased under drought conditions in all six species, but began to decrease when the drought conditions became more severe. The largest decrease in protein content under severe drought conditions was in S. moorcroftiana (a decrease of 39.22%, compared with the peak protein concentration). The chlorophyll concentrations in the leaves of the six species first increased and then decreased as the drought conditions became more severe. In the moderate drought period, the chlorophyll content of seedling leaves began to recover, probably because of a decrease in leaf water content. In all six species, the chlorophyll content on day 24 of the drought was lower than that on day 0. The largest decrease in chlorophyll concentration was in C. salesovianum (15.43 mg/g). The soluble starch contents in all six species decreased under drought because of a reduction in photosynthesis; however, all species showed an increase in soluble sugars content, which improved the osmotic adjustment capability of cells. The largest increases in soluble sugars contents and the largest reductions in starch contents were in S. moorcroftiana and C. arborescens . These species were able to retain higher cell turgor pressure at lower water potential, compared with the other species. After day 16 of the drought treatment, the decreases in starch and soluble sugar contents in the leaves indicated that prolonged water stress caused decomposition of biomass, reduced biosynthesis, and a weaker ability for osmotic adjustment. The drought resistance of plants is the sum of many physiological factors, and represents complex interactions among these factors. Thus, it is a complicated physiological adjustment mechanism. The six species were ranked differently in terms of each of the physiological indexes measured. Therefore, we used principal component analysis to select the most important physiological indexes of drought resistance: chlorophyll, MDA, and starch contents. The results of the principal component analysis indicated that species could be ranked, in terms of most to least drought resistant, as follows: C. arborescens > H. multijugum > S. moorcroftiana > B. diaphana > S. laevigata > C. salesovianum.

以青藏高原6种植物：红花岩黄芪（ Hedysarum multijugum Maxim.）、西北沼委陵菜（ Comarum salesovianum （Steph.）Asch. et Graebn.）、鲜黄小檗（ Berberis diaphana Maxim.）、鲜卑花（ Sibiraea laevigata （Linn.）Maxim.）、树锦鸡儿（ Caragana arborescens （Amm.）Lam.）、砂生槐（ Sophora moorcroftiana （Benth.）Baker）为试材进行干旱胁迫模拟盆栽试验，通过对比6种植物叶片中丙二醛（MDA）、脯氨酸、可溶性蛋白质、叶绿素、可溶性糖、淀粉含量的变化，对供选植物进行抗旱性能分析与评价，为在青藏高原地区筛选优良耐旱植物提供参考依据。设置土壤含水量占田间持水量80%以上为正常水平，50%-70%为轻度干旱，30%-50%为中度干旱，低于30%为重度干旱。研究表明，6种供试植物叶片MDA含量逐渐升高，当土壤含水量占田间持水量12%左右时达到最大值，树锦鸡儿的增幅较另5种苗木最小，而峰值最大。脯氨酸含量都呈增加趋势，其中砂生槐最高，为9981.67 mg/g，峰值与对照值相比，砂生槐增加最多为37.43 倍，鲜卑花最小为0.49 倍。苗木叶片中可溶性蛋白质含量总体表现出现增大后减小的规律，且所有测定值都高于正常水分条件下的含量。6种苗木的叶绿素含量在干旱胁迫下总体呈现先降低再升高最后再降低的趋势，24 d时均低于对照值，下降最多的为西北沼委陵菜（15.43 mg/g）。由于干旱下苗木的光合产物转化受抑，以淀粉形式的累积量减少，所以6种苗木的可溶性糖含量呈上升趋势，而淀粉含量呈下降趋势，通过积累可溶性糖以提高细胞的渗透调节能力。砂生槐、树锦鸡儿的可溶性糖含量增幅与淀粉含量的减少明显高于其余苗木，使其在较低叶水势下仍保持较高的细胞膨压，以减缓水分胁迫的不利影响。主成分分析表明，6种苗木抗旱性由强到弱依次为：树锦鸡儿、红花岩黄芪、砂生槐、鲜黄小檗、鲜卑花、西北沼委陵菜。

Plateau wetland provides an ecological protection barrier for the safety of watershed. As appearance of global climate warming and climatic anomaly, to understand the physiological and biochemical response of aquatic plants in the plateau region to the climate change and the harms under the temperature stress is critical for maintaining the plateau ecosystem and dealing with the climate change. 4 dominant plant species of Scirpus tabernaemontani , Zizania caduciflora and Heleocharis liouana , Sparganium simplex with their original soils in the lakeside of Napahai, a typical wetland in plateau region of northwestern Yunnan were selected to study the impacts of regional climate condition variations on physiological and biochemical properties of those plants. Got with local climate conditions of Napahai in Shangrila those plants with their growing soils were removed as a soil-plant unit to Lashi Lake in Lijiang and Dianchi watershed in Kunming where the climate conditions are different. Comparing with original growing area, the variations of index of physiological and biochemical to indicate adversity stress, including MDA, Pro, SS and POD were analyzed under the impacts of climatic change. The results showed that even though wetland plant is azonal plant but affected significantly by the climate change and the response to the climate change was different from plants. Such widespread species as Scirpus tabernaemontani and Zizania caduciflora could well adapt to climate warming and grow better. With temperature rise, both of their biomass increased to 196% and 190% in Lashihai Lake and 487% and 408% in Dianchi watershed, respectively. But content of MDA, Pro,POD all fell from 16%, 27%, 14% in Lashi Lake to 31%, 52%, 48% in Dianchi watershed for Scirpus tabernaemontani , and 24%, 12%, 58% in Lashihai Lake to 24%, 25%, 73% in Dianchi watershed for Zizania caduciflora , respectively. In spite of the stress of climate change, Heleocharis liouana , another widespread species could resist the alterability through its own metabolic regulations, which reflected the strong climate adaptability of widespread species. By contrast, Sparganium simplex, a narrowly spread species sustained great damage for it was too sensitive to the climate change. With the temperature rise the biomass rising at beginning to 17% in Lashihai Lake, and then dropped to 20% in Dianchi watershed. MDA and Pro decreased at beginning to 0.001387 μmol/g and 13.386891 μg/g, and then increased to 0.002739 μmol/g and 18.172878 μg/g, respectively. For such a narrow distribution species, it would face the survival crisis along with the change of the climate conditions. That reflected the fragility of plateau wetland ecosystem and its importance under global warming. Thus, the potential ecological risk behind the maintaining of plateau wetland ecosystem was revealed.

高原湿地是我国重要的生态屏障，关乎流域生态安全。随着气候变暖和极端气候事件频发，探讨高原湿地植物对气候变化的生理生化响应及温度胁迫带来的伤害，对维系高原湿地生态系统的稳定，应对全球气候变化具有重要意义。以高原地区典型湿地纳帕海为研究对象，将适应了纳帕海湿地气候条件的4种优势植物连同生长基质组成的植物-土壤单元，移至不同区域气候条件的拉市海湿地和昆明滇池流域，分析气候变化影响下，4种湿地植物原位异地后的丙二醛（MDA）、游离脯氨酸（Pro）、可溶性糖（SS）、过氧化物酶（POD）含量等反映植物受到逆境胁迫的生理生化指标变化。研究结果表明，湿地植物虽是隐域植物，但气候变化对其生长产生显著影响，不同湿地植物对气候变化的适应性不同，水葱（ Scirpus tabernaemontani ）和茭草（ Zizania caduciflora ）等广布种能够很好地适应气候变暖，两者生物量均随温度上升而增加，在拉市海的增长率分别高达196%和190%，在昆明分别增至487%和408%，MDA、Pro、POD含量则随温度上升而下降，在拉市海的最高降幅分别为16%和24%、27%和12%、14%和58%，在昆明的最高降幅分别为31%和24%、52%和25%、48%和73%，气候的暖化更有利于其生长。刘氏荸荠（ Heleocharis liouana ）虽为广布种，尽管气候变化对其产生了胁迫，但能通过调节自身的代谢物质来抵御这种变化，反映了广布种对气候变化较强的适应性。小黑三棱（ Sparganium simplex ），对气候变化较为敏感，随温度的升高其生物量在拉市海的增长率达17%，而在温度更高的昆明则减少了20%，呈现先升高后下降的趋势，同时体内各相关抗逆指标也呈现先下降后上升的趋势，MDA降至0.001387 μmol/g，后迅速增至0.002739 μmol/g、Pro降至13.386891 μg/g，后增至18.172878 μg/g，温度升高到一定程度对其产生了不利影响。对于这样一种生态幅较窄的物种，随着气候条件的改变，其生存将面临极大的挑战，显示了高原湿地在全球变暖大背景下的脆弱性，以及高原湿地生态系统维系存在的潜在危机。

The southern edge of the Taklimakan Desert is one of the most serious desertification areas in China. Natural vegetation type is scarce in desert-oasis transition zone，and [Alhagi sparsifolia，][Tamarix ramosissima] and [Karelinia caspica] are the main constructive species and dominant plants. Therefore, it is necessary to introduce some new species which have strong drought resistance, high water use efficiency and high economic values. Three kinds of three-year-old sand fixing plants， Xanthoceras sorbifolia （X） Bunge，[Hedysarum scoparium] Fisch.et Mey（H），and [Berberis thunbergii] cv. Atropurpurea（B） were taken as the experimental materials in this experiment, their physio-ecological responses in the period from persistent drought to short-time re-watering were investigated in this area. The purpose of this paper was to understand physiological and ecological responses of the three introduction plants to soil moisture changes. The results showed that re-watering after drought stress due to the increase of soil moisture results in increase in chla，chlb，chl and chla/b of H and B significantly, while the four indexes of X reduce. Soil moisture changes had relatively larger impact on the chla. Total chlorophyll of H and B increased by 46.13%，60.26%，but X decreased by 21.32%. MDA and SS contents of the three plants did not decrease but a significant increase and both index of X increased dramatically，206.32% and 199.40% respectively; while the Pro content was inordinately lower and B had a big reduction, which is 87.86%. The morning and noon water potential of three species declined with the increase of soil moisture；morning potential reduction of three plants were 115.25%，100.59%，90.97% and morning potential reduction of three plants were 86.92%，5.74%，11.20% respectively. Especially，water potential of H and B changed relatively smaller, which showed that signs of water deficit of the two plants was not significant. Compared to the three plants，X and H had a strong resistance to drought，and B was more sensitive to soil moisture change. On the one hand，the innovative point of our experiment is to select three plants under natural conditions which experienced drought and sporadic rainfall and compare the physiological and biochemical index and water potential changes of three plants to analyze the drought resistance and environmental adaptability of them. On the other hand，our experiment has a good application value. The results provide theoretical references for introduced plants adaptability and plant species selection in shelterbelt construction in the research area.

在塔克拉玛干沙漠南缘的中国科学院策勒沙漠研究站植物引种筛选实验区内，以3 a生文冠果、花棒和紫叶小檗为实验材料，研究三种植物经历持续干旱到短期复水过程中的生理生态响应。结果表明：（1）干旱复水后花棒和紫叶小檗的chla、chlb、叶绿素总量以及chla/b值均随土壤含水量的增加而显著增加，文冠果的叶绿素及其组分含量减少。水分变化对chla含量影响较大。（2）三种植物的MDA含量、SS含量在复水后并没有减少，而是显著的增加，文冠果的增加量最大；各物种的脯氨酸的含量降低，紫叶小糪减少的最多。（3）三种植物的清晨水势和正午水势随土壤水分含量的增加而降低，花棒和紫叶小檗的水势变化较小，水分亏缺迹象不显著。文冠果和花棒的抗逆性较强，而紫叶小檗对水分变化比较敏感。本研究结果可为研究区引种植物的适应性及防护林建设中的植物种选择提供理论参考。

The physiological characteristics of Pennisetum longissimum var. intermedium seedlings under three treatments of PEG-6000,low temperature and salt stress were studied using simulation adversity stress methods. The resistance and ecological adaptability were analyzed and comprehensively evaluated: 1) With increased concentrations of PEG the soluble proteins content initially increased but then decreased before increasing again. Soluble sugar initially increased but then decreased and had a maximal value when PEG was 5%. The content of MDA sharply increased at first,then remained stable and finally decreased significantly after a maximal value when PEG was 5%. The activity of SOD sharply decreased at first,then increased slowly then increased significantly. It had a minimal value when PEG was 5% and a maximal value with 20% PEG. 2) The contents of soluble protein and soluble sugar and the activity of SOD increased at first but then decreased with low temperature stress. The content of proline increased with increasing temperatures and MDA also showed an increasing trend. 3) With increased concentrations of salt,the soluble protein content initially increased but then decreased while the contents of soluble sugar,proline and MDA increased. SOD activity showed a slight increase at first,then slowly reduced followed by a rapid decline. Correlation analysis showed that the content of proline was significantly negatively correlated with soluble sugar concentration under PEG treatment. With low temperature stress of 4 hours,the contents of MDA were significantly positively correlated with soluble sugar and proline. With NaCl treatment,the content of soluble sugar was significantly positively correlated with MDA and proline,the activity of SOD was significantly negatively correlated with soluble sugar and MDA while it was significantly positively correlated with soluble protein. To sum up,the physiological dynamic changes of P. longissimum var. intermedium in its response to inverse factor stress reflects its adaptive response of resistance to adversity stresses and reducing injury.

采用PEG-6000、低温和NaCl处理模拟逆境胁迫的方法,系统研究了中型狼尾草幼苗在3种不同胁迫条件下的生理生化特性的变化,并对其抗逆性、各生理生化指标的相关性进行了综合评价与分析。结果显示,1)随着PEG浓度的增加,可溶性蛋白含量表现为先增后降再增的趋势;可溶性糖含量呈现先增后降,在PEG 5%时达到最大;脯氨酸含量显著升高,在PEG 20%时含量是CK的6.0倍;MDA含量呈现“急剧增加—相对稳定—迅速下降”的变化趋势,PEG 5%时MDA累积量达到最大;SOD活性总体上呈“急剧下降—微增—迅速上升”的趋势,PEG 5%时最低,PEG 20%时达到最大。2)低温胁迫过程中,可溶性蛋白和可溶性糖含量均随温度降低总体呈现先升高后下降的趋势;脯氨酸含量随温度的降低均呈升高趋势;MDA含量随低温处理时间的延长而增大;SOD活性随温度的降低总体呈现先升高后下降的趋势。3) 随着NaCl胁迫水平的加强,可溶性蛋白含量表现为先增后降的变化趋势;可溶性糖、脯氨酸和MDA含量均随着NaCl浓度的增大而增加;SOD活性则呈现“微增—缓慢降低—急剧下降”的变化趋势。相关性分析结果显示:PEG胁迫下,脯氨酸含量与可溶性糖含量呈显著负相关;低温4 h胁迫下,MDA含量与可溶性糖含量显著正相关,与脯氨酸含量极显著正相关;NaCl胁迫下,可溶性糖含量与脯氨酸含量和MDA含量极显著正相关,SOD活性与可溶性糖含量、MDA含量呈显著负相关,而与可溶性蛋白显著正相关。以上结果表明,中型狼尾草适应逆境胁迫受到多种生理生化的调节,且各生理生化物质之间存在一定的相关性,其生理指标的动态变化是中型狼尾草应答逆因子胁迫的重要生理调节机制,体现了其抵抗逆境胁迫、减轻伤害的适应性反应。

Drought is one of the most important abiotic factors limiting plant growth, development and survival. Due to global warming, the drought episodes in the future will become more frequent and severe. Therefore, the plant responses to drought stress, especially the droughtresistant mechanisms, have been a focus of the studies. This paper summarized the plant growth and physiological responses to drought stress, and proposed a staged response strategy of plants for the adaptation to natural drought stress. Overall, from drought initiation to droughtinduced death, plants experienced five stress stages with increasing drought intensity,  i.e ., drought initiation-mild drought-moderate drought-severe drought-extreme drought, and the plant responsive and adaptive process in this whole event could be acute response-active adaptation to mild and severe drought stresses-passive adaptation to extreme drought stress. The essential function of the plant droughtresistant mechanisms varied with drought stress stages. Some key scientific problems and research directions about the staged response characteristics of plants to drought stress needed to be solved urgently in the future were pointed out.

干旱是影响植物生存、生长和分布的最重要的非生物胁迫之一,全球暖干化将加剧干旱胁迫.植物对干旱胁迫的响应和适应机制一直是 学术研究的热点领域.本文综述了植物应对干旱胁迫的生长和生理响应,在已有的研究结果基础上,提出了植物应对干旱胁迫的阶段性响应策略.从干旱开始到干旱致死,植物经历了干旱开始—轻度干旱—中度干旱—严重干旱—极端干旱5个阶段,分别对应着应激响应—主动适应—被动适应3种响应方式和适应机制.不同阶段中植物抗旱机制的核心任务不同.最后提出了研究植物阶段性响应策略需要解决的关键科学问题及研究方向.

In this study, seven species of Wild Poa in Gansu province were selected to measure the physiological responsive indices of malondialdehyde (MDA), soluble protein (SP), catalase (CAT), superoxide dismutase (SOD), free proline and soluble sugar (SS) under simulated drought stress. Further, the relationship between drought resistance and physiological indicators, mean annual precipitation of source and was evaluated. The results showed that the contents of free proline, SS and MDA in leaves increased gradually with increasing drought stress, the CAT and SP showed a decreasing trend with increasing drought stress, while the SOD activity increased a little and then decreased slowly. The comprehensive evaluation values were negatively correlated to the contents of MDA (p 0.05). The drought resistant capacities of the seven species were evaluated by standard deviation coefficient allocation weighted method, the seven species were thereby classified into three type: the first category was drought resisted, including P. pratensis, the second category was medium drought resisted, including P. dolichachyra, P. anqustifolia, P. crymophila and P. poophaqorum, and the drought resistance of the third category was weak, including P. declinata and P, micrandra.

以采集于甘肃境内的7种野生早熟禾（Poa L.）为材料,采用盆栽模拟自然干旱条件,研究了叶片游离脯氨酸（F-pro）、可溶性糖（SS）、可溶性蛋白(SP)和丙二醛(MDA)含量及过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性对干旱胁迫的生理响应,分析了生理指标及采集地年均降水量与抗旱性的关系,以期为早熟禾抗旱品种的选育提供依据。结果表明:随干旱胁迫时间的延长,叶片F-pro、SS和MDA含量逐渐增加,CAT活性和SP含量逐渐减少,SOD活性呈先增强后减弱的趋势。MDA含量与抗旱综合评价值极显著负相关（p＜0.01）,CAT活性与抗旱综合评价值显著正相关（p＜0.05）,二者可作为野生早熟禾抗旱性评价的主要指标。材料采集地的年均降水量与抗旱综合评价值负相关,但相关性不显著（p＞0.05）。采用标准差系数赋予权重法对抗旱性进行综合评价,可将7个材料分为3类:第1类抗旱,为草地早熟禾（Poa pratensis）;第2类中等抗旱,包括长稃早熟禾（Poa dolichachyra）、细叶早熟禾（Poa anqustifolia）、冷地早熟禾（Poa crymophila）和波伐早熟禾（Poa poophaqorum）;第3类抗旱性弱,包括垂枝早熟禾（Poa declinata）和小药早熟禾（Poa micrandra）。

In this study Longdong( strong drough- t resistance) Gongnong No 1( medium drough- t resistance) and BL -02 - 329( weak drough- t resistance) were chosen as experimental material to study the change of water metabolism and two os - motic adjustment substances in the leaves of alfalfa under drought stress.The results showed: the water potential and water relative content in the leaves of alfalfa decreased and water saturated deficit in the leaves of alfalfa increased under drought stress.There were higher decrease extent of water potential and lower decrease extent of water relative content in the leaves of strong drough- t resistance alfalfa under drought stress. At the same time the proline content and soluble sugar content increased in the leaves of three alfalfa, the two substances both have adjustive function to three alfalfa under drought stress. Proline is the main adjustment substance and the content and the increase extent can reveal drough- t resis - tant of alfalfa cultivars.

以陇东(耐旱)、公农1号(耐旱性中等)、BL-02-329(不耐旱)3种抗旱性强弱差异较大的紫花苜蓿为试验材料,对干旱胁迫下其叶片水分代谢与两种渗透调节物质的变化进行研究,结果表明:干旱胁迫下苜蓿叶片水势、叶片相对含水量降低,水分饱和亏缺增加,总体上3种紫花苜蓿叶片抗旱性强的材料其叶片水势降低的幅度较大,水分饱和亏缺上升幅度及叶片相对含水量下降幅度较低。干旱胁迫下,可溶性糖及脯氨酸含量上升,2种渗透物质对3种紫花苜蓿均有渗透调节作用。脯氨酸是三种紫花苜蓿主要渗透调节物质,脯氨酸含量的多少及增加的幅度能反映苜蓿的耐旱性。

we studied different geographic population′s Leymus chinensis, Which came from the seeds we got from different typical steppes of the Inner Mongolian Plateau.we selected the Leymus chinensis of five sampling point,analyses the free proline and water content of the leaf under the force of different consistency PEG(0%,15% and 30%)and different force time(12 h,24h and 36h)Using UPGMA analysis,we found that the five geographic population could be divided into three groups according to the changes of the ...

将 1 994年从内蒙古不同地区和吉林采集到的羊草 ( Leymuschinensis)种子进行栽培试验 ,分析了 5个样点 (阿旗、定位站、西乌旗、谢尔塔拉、吉林 )的羊草在不同浓度聚乙二醇 ( PEG=0 %、1 5%、3 0 %)的胁迫下 ,及不同胁迫时间 ( 1 2 h、2 4 h、3 6h)条件下 ,叶片游离脯氨酸和水分的含量。通过聚类分析表明 :不同地理种群的羊草按水分胁迫后游离脯氨酸含量和水分含量都可划分成 3类 ,而且所得的结果基本相似。结果还证明 ,抗旱性强的样品游离脯氨酸积累时间长 ,维持积累量大 ;羊草的抗旱性与脯氨酸积累特性与其生境有相当的联系。

The grasses Agropyron cristatum , Stipa bungeana , Cleisto genessongorica, and Bothriochloa ischaemum are widely distributed on the Loess Plateau, and all are drought-resistant to varying degrees. However, little is known about the responses of their antioxidant systems to drought stress. The objective of this study was to investigate the antioxidant properties of four native grasses in response to drought stress, to provide a theoretical basis for selecting grasses suitable for vegetation/ecological restoration on the Loess Plateau. The treatments consisted of three levels of drought; 80, 60, and 45% of field capacity (FC) levels. These moisture levels were obtained by a weighing method using a pot experiment system. Leaf samples were taken from the four native grasses after 30 days of drought treatments. Assays were conducted on the leaf tissue to determine the activities of the following antioxidant enzymes:superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione peroxidase (GPX, EC 1.11.1.9). In addition, we determined the contents of hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), reduced glutathione (GSH), reduced ascorbic acid (AsA) and carotenoid (Car) in the leaves. The results showed that the MDA and H 2 O 2 contents in the leaves of the four grasses increased with increasing levels of drought stress. These results suggested that all the grasses suffered oxidative damage under different levels of drought stress and that the oxidative damage became more serious with increasing levels of drought stress. According to their MDA and H 2 O 2 contents, the magnitude of oxidative damage was greatest in S. bungeana , followed by B. ischaemum, then C. genessongorica , and then A. cristatum . The four grasses enhanced their antioxidant capacity by increasing activities of antioxidant enzymes and the contents of antioxidant substances under different levels of drought stress. The four grasses all belong to the Gramineae family and inhabit the same ecological environment. Therefore, they showed some similarities in their antioxidant responses to drought stress. At both 60% and 45% FC levels, all four grasses protected themselves against drought-induced oxidative damage by increasing the activities of SOD, CAT, APX, GR, DHAR, MDHAR, and GPX, and their AsA content. However, since the four grasses were all different species, there were also some differences in their antioxidant responses. At both 60% and 45% FC levels, A. cristatum , C. genessongorica, and B. ischaemum protected themselves by increasing their Car content, while S. bungeana and B. ischaemum protected themselves by increasing POD activity. At the 60% FC level, A. cristatum showed an increase in GSH content. The overall trend in antioxidant capacity for the four grasses was as follows: A. cristatum > C. genessongorica > B. ischaemum > S. bungeana , as determined by comprehensive evaluation using the subject function method. Above results suggested that A. cristatum is the most drought-resistant, followed by C. genessongorica and B. ischaemum, while S. bungeana is the least drought-resistant. Thus, A. cristatum , C. genessongorica, and B. ischaemum are suitable grasses for vegetation/ecological restoration on the Loess Plateau.

采用盆栽实验,对干旱胁迫下黄土高原4种乡土禾草冰草、长芒草、无芒隐子草和白羊草叶片过氧化氢(H 2 O 2 )、丙二醛(MDA)含量、抗氧化酶超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDHAR)、谷胱甘肽过氧化物酶(GPX)活性和非酶抗氧化物质还原型抗坏血酸(AsA)、还原型谷胱甘肽(GSH)、类胡萝卜素(Car)含量进行了测定。 结果表明:随着干旱胁迫程度的加剧,4种乡土禾草叶片H 2 O 2 、MDA含量均呈增加趋势,这说明它们均遭受了干旱所造成的氧化胁迫,且干旱程度越大其遭受的氧化胁迫也越大。由于4种乡土禾草均为禾本科植物并生存于相同的生态环境中,它们在抗氧化特性上具有一定共性。在60%FC和45%FC干旱胁迫下,4种乡土禾草均可以通过增加抗氧化酶SOD、CAT、APX、GR、DHAR、MDHAR、GPX活性和非酶抗氧化物质AsA含量来抵御干旱所造成的氧化胁迫。由于种属差异,4种乡土禾草的抗氧化特性也存在差异。在60%FC和45%FC干旱胁迫下,冰草、无芒隐子草和白羊草还通过增加非酶抗氧化物质Car含量增强抗氧化能力,长芒草和白羊草则还可通过增加POD活性抵御干旱。在60%FC干旱胁迫下,冰草还可通过增加非酶抗氧化物质GSH含量提高其抗氧化性。采用隶属函数法对4种乡土草种抗氧化能力的综合评价表明,冰草的抗氧化能力最强,其次为无芒隐子草和白羊草,长芒草的抗氧化能力最差。