Comparative Studies on Water Relations and Xeromorphic Structures of Some Plant Species in the Middle Part of the Desert Zone in China

The mean value of leaf water potential (LWP) of the mesophytes, the less-succulent xerophytes and the succulent xerephytes was –13.5, –18.09 and –26.09 bars respectively. The bound water content (BWC), and the ratio of bound water content to free water content (B/E ratio) for the succulent xerophytes (174.0% and 4.8) were higher than those for the mesophytes (52.5% and 0.37) and the less-succulent xerophytes (76.8% and 1.0). The transpiration rate of the mesophytes, less-succulent xerophytes and succulent xerophytes was 1146.5, 866.3 and 422.8 mg/g. fw. h respectively. The water holding capacity (WHC) of the succulent xerophytes was the strongest among those of the three types, while that of the mesophytes was the weakest. The xerophytes, both the succulent and the less-succulent, have the following xeromorphic structures: thick cuticle, sundan stomata, dense epidermal hairs, well-developed palisade tissue and degenerated spongy tissue, the high ratio of palisade tissue to spongy tissue, and equilateral leaves. Besides, succulent xerophytes possess other xeromorphic structures: thick leaves, well-developed water storing tissue, high ratio of water tissue to leaf thickness, and the succulent leaves. The mesophytes exhibit the following mesophilous structures, thin cuticle, levelling or arching up stomata, low ratio of palisade tissue to spongy tissue, and back-belly leaves.     

我国荒漠不同生态类型植物的旱生结构

本文研究了我国荒漠15种不同类型植物的解剖结构。结果表明,超旱生和旱生植物具有典型的旱生结构,尤以超旱生植物明显,例如沙冬青、梭梭。 旱生结构的基本特征是：叶片及角质层厚,具表皮毛、腺毛、瘤状或乳状突起,气孔下陷,栅栏组织及贮水组织发达,构成等面叶及肉质叶,具含晶细胞和粘液细胞;维管束鞘、维管束帽及纤维细胞的存在,增强了植株的坚固性。中生植物叶片及角质层较薄：气孔平置或拱起,栅栏组织及海绵组织同等发育,胞间隙大,为背腹叶,这是典型的中生结构。     

A Preliminary Study of Xeromorphism of Some Important Xerophytes Growing in Tungeli Desert

In the present paper, using photo-microscopic method, the xeromorphism of some important xerophytes growing in south-east edge of Tungeli desert were determined. The xerophytes appeared to be different from mesophytes at common characteristics, lower in ratio between superficial area and mesophyll tissue volume and higher in ratio between palisade tissue and parenehyma. The xerophytes may be divided into two major groups; selerophylous xerophytes are characterized by a lot of small stomata, a large number of epidermal hair and developed conducting tissue and succulent xerophytes are characterized by a few of big stomata, thickness cuticle and developed water storage tissue. The role of xeromorphism in drought-resistance was also discussed.     

内蒙古锡林河流域植物功能群组成及其水分利用效率的变化--依水分生态类群划分

依照植物水分生态类群,将锡林河流域主要植物种划分为6个植物功能群:呈生植物、中旱生植物、旱中生植物、中生植物、湿中生植物和湿生植物.沿土壤水分梯度,我们调查了8个植物群落的功能群组成及其δ13C值.结果表明:1)在水分状况不同的8个群落中,植物功能群的组成有很大差异.在较湿润生境中(沼泽化草甸和盐化草甸),湿中生和湿生植物成为优势种并构成地上生物量的主要部分;在干旱生境中(草甸草原、典型草原和退化草原),旱生和中旱生植物占绝对优势并构成群落生物量的90%以上;2)不同功能群δ13C值表现为:旱生植物(26.38‰)=中旱生植物(26.51‰)＞旱中生植物(-27.02‰)＞中生植物(-27.56‰)=湿中生和湿生植物(-27.80‰),表明随着不同水分生态类群所适应生境从干旱到湿润逐渐转变,植物的水分利用效率显著降低;3)在土壤水分状况不同的生境下,旱生植物始终维持相对较高的δ13C值和水分利用效率;而中旱生植物的δ13C值表现出较大的变化幅度,表明其对土壤水分的改变更敏感;4)旱生植物叶片脯氨酸含量最高;旱中生、中旱生和中生植物次之;湿中生和湿生植物脯氨酸含量最低.不同水分生态类群脯氨酸含量与其δ13C值和地上生物量呈显著正相关关系.     

内蒙古锡林河流域植物功能群组成及其水分利用效率的变化——依水分生态类群划分

依照植物水分生态类群,将锡林河流域主要植物种划分为6个植物功能群:旱生植物、中旱生植物、旱中生植物、中生植物、湿中生植物和湿生植物。沿土壤水分梯度,我们调查了8个植物群落的功能群组成及其d13C值。结果表明:1)在水分状况不同的8个群落中,植物功能群的组成有很大差异。在较湿润生境中(沼泽化草甸和盐化草甸),湿中生和湿生植物成为优势种并构成地上生物量的主要部分;在干旱生境中(草甸草原、典型草原和退化草原),旱生和中旱生植物占绝对优势并构成群落生物量的90%以上;2)不同功能群d13C值表现为:旱生植物(-26.38) = 中旱生植物(-26.51) > 旱中生植物(-27.02) > 中生植物(-27.56) = 湿中生和湿生植物(-27.80),表明随着不同水分生态类群所适应生境从干旱到湿润逐渐转变,植物的水分利用效率显著降低;3)在土壤水分状况不同的生境下,旱生植物始终维持相对较高的d13C值和水分利用效率;而中旱生植物的d13C值表现出较大的变化幅度,表明其对土壤水分的改变更敏感;4)旱生植物叶片脯氨酸含量最高;旱中生、中旱生和中生植物次之;湿中生和湿生植物脯氨酸含量最低。不同水分生态类群脯氨酸含量与其d13C值和地上生物量呈显著正相关关系。     

Response of photosynthesis and respiration of resurrection plants to desiccation and rehydration

Using non-invasive techniques (CO₂ gas exchange, light scattering, light absorption, chlorophyll fluorescence, chlorophyll luminescence), we have analysed the response of respiration and photosynthesis to dehydration and rehydration of leaves of the resurrection plants Craterostigma plantagineum Hochst., Ramonda mykoni Reichb. and Ceterach officinarum Lam. et DC. and of the drought-sensitive mesophyte spinach (Spinacia oleracea L.). The following observations were made: (i) The rate of water loss during wilting of detached leaves of drought-tolerant resurrection plants was similar to that for leaves of the sensitive mesophyte, spinach. Leaves of Mediterranean xerophytes lost water much more slowly. (ii) Below a residual water content of about 20%, leaves of spinach did not recover turgor on rewatering, whereas leaves of the resurrection plants did. (iii) Respiration was less sensitive to the loss of water during wilting in the resurrection plants than in spinach. (iv) The sensitivity of photosynthesis to dehydration was similar in spinach and the resurrection plants. Up to a water loss of 50% from the leaves, photosynthesis was limited by stomatal closure, not by inhibition of reactions of the photosynthetic apparatus. Photosynthesis was inhibited and stomates reopened when loss of water became excessive. (v) After the leaves had lost 80% of their water or more, the light-dependent reactions of photosynthetic membranes were further inhibited by rewatering in spinach; they recovered in the resurrection plants. (vi) In desiccated leaves of the resurrection plants, slow rehydration reactivated mitochondrial gas exchange faster than photosynthetic membrane reactions. Photosynthetic carbon assimilation recovered only slowly.     

骆驼蓬营养器官的旱生结构

 骆驼蓬是生长在荒漠或盐碱地区的旱生植物,具有显著的旱生结构特征。主根粗壮,其中柱周围产生2或3轮呈同心环状排列的异常维管束。这种异常结构对旱生植物具有重要的生态学意义。茎肉质,其皮层、韧皮部,尤其是髓内具有发达的贮水薄壁组织细胞。叶片肉质,光滑无毛。其表皮细胞的外切向壁有较厚的角质层,表面具皱纹状突起。气孔器与表皮细胞平齐,面积较大,而密度较小。栅栏组织发达,为环栅型,包围着发达的贮水组织。叶脉维管束不发达。其叶表面积与体积之比远比中生植物小。根据以上营养器官形态结构特征,可以认为骆驼蓬是典型的多浆汁旱生植物。     

麻栎成熟合子胚外植体体胚发生和植株再生

为探索麻栎快速繁殖技术新途径,以成熟合子胚为外植体诱导体胚发生,进一步培养形成幼苗。结果表明:体胚诱导以MS+1.0mg.L-1 6-BA+1.0mg.L-1 IBA+1.0g.L-1谷氨酰胺+0.5g.L-1脯氨酸为最优,培养30d诱导率达70.0%;体胚成熟以1/2MS+2.0mg.L-1 6-BA+0.5mg.L-1 IBA+2.0mg.L-1 ABA+4.0g.L-1谷氨酰胺+2.0g.L-1脯氨酸为佳,培养60d,体胚完全成熟;体胚萌发最适培养基为1/2MS+0.2mg.L-1 6-BA+10g.L-1山梨醇,且冷处理有利于体胚的萌发,萌发率高达100%,萌发培养80d,形成再生植株。     

锦鸡儿属7种植物叶的生理生化分析

对锦鸡儿属7种植物的叶片进行了生理生化指标测定,包括游离脯氨酸、丙二醛和保护酶（过氧化物酶POD、过氧化氢酶CAT）等的含量,并对同一地区引种的不同种及分布于不同地区的同一植物进行了对比分析。结果表明：同一地区引种的不同植物的生理特征表现出明显的趋同,旱生植物趋于中生化,中生植物趋于旱生化以此共同适应相同的环境;不同地区的同一植物表现出一定适应性分化,说明植物为适应不同的生态环境进行着相应的生理调节。     

草毡寒冻雏形土CO2释放特征

研究了植物生长季节海北高寒草甸生态系统高寒嵩草草甸覆被下草毡寒冻雏形土的 CO2 释放速率。其结果表明 :CO2 释放速率有明显的日变化和季节动态。日最大排放速率多出现在 1 4 :0 0～ 1 6:0 0时 ,最小排放速率在 6:0 0～ 8:0 0时。植物生长季日最大振幅为 797.75mg/m2·h,最小振幅 1 97.33mg/m2·h。CO2 排放白天大于夜晚。不同物候期 CO2 释放速率不同 ,其顺序为草盛期 >枯黄期 >返青期。生长季土壤 CO2 释放速率的范围是 4 41 .72 mg/m2 · h± 1 55.2 9mg/m2· h,最大日均值为 681 .0 6mg/m2 · h( 7月 1 6日 ) ,最低值 1 76.65mg/m2 · h ( 6月 1日 )。退化草地土壤 CO2 释放速率明显低于未退化草地 ,生长季平均日均值低 1 37.4 7mg/m2·h。相关分析表明 :土壤 CO2 排放速率与气温、地表温度、土壤5cm、1 0 cm、1 5cm、2 0 cm、30 cm地温均呈显著和极显著相关关系。温度是影响土壤 CO2 释放速率的主要因子。     

Ecologically based differences in the structure of grass stem

A quantitative anatomical study of the stem structure of grasses of various ecological groups: xerophytes, mespohytes, ephemers, hydrophytes and psammophytes (a total of 30 species) was carried out. The proportions of the various tissues in the stem were expressed as a percentage of the cross-sectional area of the stem. Stems of hydrophytes were found to have only small proportion of mechanical (4-8%) and conducting (2-5%) tissues but a large pro. portion of parenchyma (85-93% - primary cortex and basic parenchyma) and air system (38-40% - parenchyma channels or specialized aerenchyma). The stems of xerophytes possess a highly developed sclerenchyma (30-50%) and vessel bundles (6-13%) while the parenchyma is less developed (36-60%). The cells of the stems of hydrophytes are larger than those of xerophytes, but the cell membranes are thinner. The structure of mesophytes is intermediate between that of hydrophytes and xerophytes and the structure of ephemers is very similar to that of mesophytes. Psammophytes differ from xerophytes in having more mesomorphous features.     

不同环境条件下沙生植物的CO2气体交换研究

对腾格里沙坡头地区两种沙生植物：油蒿（ＡｒｔｅｍｉｓｉｓａｏｒｄｏｓｉｃａＫｒａｓｃｈ．）和柠条（ＣａｒａｇａｎａｋｏｒｓｈｉｎｓｋｉｉＫｏｍ）。在旱季和雨季时ＣＯ２气体交换特点及其动态变化进行了研究,结果表明：在干旱条件下,油蒿（Ａ）和柠条（Ｃ）的光合作用均受到严重影响,其光合率率日变化日出后（７：００－９：ａ．ｍ．）有一较小高峰外,基本处于很低水平。降水后,Ａ和Ｃ的光合作用均明显提高,但Ｐｎ     

Study on Leaf Anatomy and Photosynthesis of Cymbidium sinense

The leaf surface of Cymbidium sinense(Andr.) Willd was covered with cuticle and wax. The stomata were distributed in the dorsum of the leaf, the density being 100–130 mm-2 There was a stomatal cover on each stoma. The mesophyll was not differentiated into spongy tissue and palisade tissue. No chloroplast was observed in the vascular bundle sheath cells. The chloroplast in the mesophyll cells had well developed grana, with lightly stacked thylakoids and osmiophilic granules. The highest quantum yield of functional leaf was 0.082. The light compensation point of photosynthesis was about 5 μE·m-2·s-1, the light saturation point was about 200 μE·m-2·s-1. The photosynthetic ra,e of Cymbidium sinense was very low, generally 2.0–2.6 μmol CO2· m-2·s-1. The optimum temperature of photosynthesis of one-year-old leaf was 25℃. The photosynthe,ic rate of the three-year-old leaf declined with temperature rise. The ratio of chlorophyll a/b was about 2.7. The CO2 compensation point of photosynthesis was 105–220 ppm. All these data show that Cymbidium sinense belongs to the typical shade plants with low photosynthetic rate and high CO2 compensation point that explains that the growth of Cymbidium sinense is slow in nature.     

Accumulation of Natural Growth Inhibiting Substances under Stress Conditions and Its Relation to Adaptation of Plants to Unfavorable Environments

Changes of levels of growth inhibiting substances under drought, salinity, chilling and heat stress in different types of plants were investigated. The presence of ABA in leaf extracts of several plants was identified. Levels of ABA and other inhibitors were increased under stress to different extents, depending on species of the plant and the nature of the stress. The inhibitor contents of two xerophytes, Hedysarum scoparium and Haloxylon ammoderdron, from desert region were also increased by 11.6-fold and 5.2-fold respectively when subjected to water stress, whereas that of mesophyte Robinia pseudoacacia increased 4.5-fold. Correlation between inhibitor level and drought resistance of different wheat cultivars was also noted, The resistant cv. “Hongnong No. 1” accumulated 2–3-fold more inhibitors than the nonresistant cv. “Gansu No.8” when subjected to water or saline stress. The role of growth inhibitors is the adaptation of plants to unfavorable environments was discussed.     

辽河口湿地植物多样性及物种功能型空间分布格局

辽河口湿地是我国典型的滨海湿地, 在过去几十年受人为过度干扰, 植被变化明显。本研究拟通过野外实地调查揭示辽河口湿地植物多样性及功能型的空间格局。结果表明, 潮上带的物种丰富度和Shannon-Wiener指数均高于潮间带。与潮上带相比, 潮间带的盐生植物与湿生植物比例较高, 而中性植物、甜土植物、中生植物与旱生植物的比例较低。物种丰富度、Shannon-Wiener指数以及中性植物、甜土植物、中生植物、旱生植物的比例均随着与海岸线距离的增加而增加, 盐生植物、湿生植物比例则与之相反。对所调查样地与植物物种的主成分分析(PCA)表明, 潮上带主要为芦苇(Phragmites australis)、刺儿菜(Cirsium setosum)、山莴苣(Lagedium sibiricum)等中性和甜土植物, 潮间带为盐地碱蓬(Suaeda salsa)、扁秆藨草(Scirpus planiculmis)、水烛(Typha angustifolia)等盐生植物。可见, 盐度与水位是决定辽河口湿地植物多样性及物种功能型的关键生态因子。     

Quantum yield variation across the three pathways of photosynthesis: not yet out of the dark

The convergent quantum yield hypothesis (CQY) assumes that thermodynamics and natural selection jointly limit variation in the maximum energetic efficiency of photosynthesis in low light under otherwise specified conditions (e.g. temperature and CO(2) concentration). A literature survey of photosynthetic quantum yield (phi) studies in terrestrial plants from C(3), C(4), and CAM photosynthetic types was conducted to test the CQY hypothesis. Broad variation in phi values from C(3) plants could partially be explained by accounting for whether the measuring conditions were permissive or restrictive for photorespiration. Assimilatory quotients (AQ), calculated from the CO(2) phi:O(2) phi ratios, indicated that 49% and 29% of absorbed light energy was allocated to carbon fixation and photorespiration in C(3) plants, respectively. The unexplained remainder (22%) may represent diversion to various other energy-demanding processes (e.g. starch synthesis, nitrogen assimilation). Individual and cumulative effects of these other processes on photosynthetic efficiency are poorly quantified. In C(4) plants, little variation in phi values was observed, consistent with the fact that C(4) plants exhibit little photorespiration. As before, AQ values indicate that 22% of absorbed light energy cannot be accounted for by carbon fixation in C(4) plants. Among all three photosynthetic types, the phi of photosynthesis in CAM plants is the least studied, appears to be highly variable, and may present the greatest challenge to the CQY hypothesis. The high amount of energy diverted to processes other than carbon fixation in C(3) and C(4) plants and the poor characterization of photosynthetic efficiency in CAM plants are significant deficiencies in our otherwise robust understanding of the energetics of terrestrial photoautotrophy.     

崖爬藤的生态生物学特征及其扦插繁殖技术

崖爬藤为葡萄科常绿或半常绿藤本,具有重要园林绿化价值。该研究采用叶片离析法和石蜡切片法研究其叶片的形态结构。结果表明:崖爬藤平均叶面积(23.1 cm~2)较大,单位叶面积干重(4.4 mg·cm~(-2))较小,成熟叶厚约为195.5μm,栅栏组织不发达,胞间隙大。利用便携式LI-6400光合测定仪、PAM-2100荧光测定仪对崖爬藤光合生理生态指标进行研究。结果表明:其PSⅡ的最大光化学效率Fv/Fm(0.818)较高;叶片的净光合速率日变化呈单峰型,没有明显的光合午休现象,最大净光合速率Pn为3.691μmol·m~(-2)·s~(-1),出现在14:00时,变化趋势与光合有效辐射Par、大气温度T、蒸腾速率Tr、气孔导度Gs等因子相同,与胞间CO_2浓度Ci相反,同时具有较高的水分利用效率(3.056μmol·mmol~(-1))。这都显示了崖爬藤喜阴湿环境,不耐寒且具有一定的耐旱特性,适合栽植于我国温度较高的南方地区。此外,以崖爬藤1~2年生老枝和当年生嫩枝为材料,经梯度溶液IBA处理进行扦插生根实验,结果表明,崖爬藤扦插繁殖迅速,生根率较高,以当年生嫩枝不经IBA处理直接扦插为最佳。该研究结果将为崖爬藤的栽培及开发利用提供重要的理论和技术指导。     

甜高粱再生体系的建立

利用甜高粱成熟种子和成熟胚作为外植体,通过愈伤组织再生途径建立了植株再生体系。结果表明,成熟种子在添加1.38 g·L^-1脯氨酸、500 mg·L^-1水解酪蛋白和3.0 mg·L^-1 2,4-D的MS培养基上可以较快地诱导出生长状态良好的愈伤组织;成熟胚在添加1.38 g·L^-1脯氨酸、500mg·L^-1水解酪蛋白、2.5 mg·L^-1 2,4-D和0.1 mg·L^-1KT的MS培养基上也能诱导出生长良好的愈伤组织。将愈伤组织转移到MS＋1 mg.L^-1 IAA＋0.5 mg·L^-1 6-BA培养基上诱导芽,然后再转移到MS＋3 mg·L^-1IBA培养基上生根后,可发育成为完整的植株。     

浙江天童常绿阔叶林藤本植物的适应生态学：Ⅰ、叶片解剖特征的比较

利用解剖学方法对浙江天童森林公园常绿阔叶林的１０属１１种木质藤本叶片的解剖特征进行了比较和因子分析,结果表明：藤本植物叶片结构在不同种类子之间具有明显的差异,同种藤本的不同植物的叶片也存在一定的差异;这些差异除受遗传因子控制外,环境因子（主要为光照和水分）也有重要作用;攀援方式对藤本叶片特征有一定影响,但未表现出规律性。尽管叶片的基本结构仍属中生类型,但也表现出一定的趋异适应,根据叶片适应特征的差异,１１种藤本植物可分为３种类型,即偏旱生或阳生叶类型（包括薜荔（Ｆicus pumila)、珍珠莲（Ficus sarmentosa var.henry)和藤构（Ｂroussonetia kaempferi)),偏阴生叶类型（羊角藤（Morinda umbellata)和昆明鸡血藤（Millettia reticulata）中和生叶类型（广东蛇葡萄（Ａmpelopsis cantoniensis)、中华常春藤（Hedera nepalensis var.sinensis)、短梗南蛇藤（Celastrus rosthoniauns)、暗色菝葜（Smilax lanceiofolia var.opaca）、薯莨（Ｄioscorea cirrhosa)和香港黄檀（Ｄalbergia millettii)。藤本叶片的各部分结构特征对生境条件的适应并未表现出一致的同步变化,存在着一定的差异或可塑性,这可能由藤本生长环境经常发生变动所致。     

Photosynthesis but not CAM responded flexibly to changes in irradiance in Plectranthus marrubioides (Lamiaceae)

Well-watered plants of Plectranthus marrubioides Benth., a crassulacean acid metabolism (CAM) species naturally inhabiting sun exposed succulent places, were grown at photosynthetically active photon flux densities (PPFD) of either 150 (LL) or 300 (HL) μmol m-2 s-1 in a controlled environment. Photosynthesis of LL plants was saturated by irradiance of ca. 500 μmol m-2 s-1 while in HL plants saturation was not reached up to 1200 μmol m-2 s-1 and photosynthetic capacity was nearly 50 % higher than in the LL plants. However, maximum photon yield was 55 % lower and compensation irradiance was 25 % higher in LL plants. The former also had larger, more succulent leaves, i.e., they were morphologically more sun adapted. On the other hand, nocturnal accumulation of malic and citric acid, nighttime CO2 gain, and the low relative carbon recycling were independent of the prevailing PPFD. Furthermore, photosynthetic performance was flexibly and reversibly adjusted in HL plants after transfer to 600 or 150 μmol m-2 s-1 while nocturnal CO2 uptake was not influenced. Photosynthesis showed a high acclimation potential to high PPFD and patterns of gas exchange became more C3-like the higher the irradiance was, without a direct effect on CAM in P. marrubioides.