UV-B辐射对南亚热带森林木本植物幼苗生长的影响

研究了UV -B辐射对广东省南亚热带森林木本植物九节、鸭脚木、猴耳环、半枫荷、山乌桕和绿化树种大叶合欢幼苗生长的影响。实验结果表明 ,UV -B辐射降低叶片光合色素的含量 ;显著降低幼苗的净光合速率、蒸腾速率和气孔导度 ;降低干物质的增长 ;抑制大叶合欢幼苗根瘤的形成     

高CO2浓度下4种豆科乔木种子萌发和幼苗生长

 本文研究了高CO2浓度(550×10-6±50×10-6)对4种豆科乔木的种子萌发和幼苗生长的影响,结果如下：(1)高CO2浓度能使光叶红豆种子萌发率提高12％,对其它种的萌发没有明显影响。(2)高CO2环境能增加4种幼苗根瘤数量,提高根瘤的固氮活性和根瘤中可溶性糖的含量。(3)在高CO2环境下生长的幼苗叶片净光合速率比对照CO2环境(约350×10-6)下生长的幼苗提高66.7％～105.9％。在高CO2浓度和对照CO2浓度下生长的幼苗,移至相同C02浓度下测定时,光合速率无明显的差异。高CO2环境下生长并测定的幼苗叶片暗呼吸速率和对照CO2浓度下生长并测定的幼苗的测值差异不大,前者较后者低5.58％～l0.55％。(4)在高CO2环境下生长的4种幼苗干物质比对照的增加29.79％～50.30％,根系增加量较大,根冠比略上升。幼苗的相对生长速率和单位叶率上升,而叶面积比率下降。(5)幼苗对高CO2环境的反应和种的生态特性有关。喜光的大叶合欢幼苗对高CO2环境的反应较大,喜光而具一定耐荫性的猴耳环幼苗次之,而耐荫的光叶红豆和茸荚红豆幼苗则较小。     

Effect of Light on Scavenging Capacity for Organic Free Radical in Leaves of Four Woody Plants

Change of antioxidant capacity of the organic-free-radical scavengers to 1.1-diphenyl-2-picrylhydrazyl (DPPH·) reagent in the leaf extracts of the seedlings and young trees of four woody species (Schima superba Gardn. et Champ., Castanopsis fissa (Champ. ex Benth.) Rehd. et Wils., Psychotria rubra (Lour.) Poir., Ardisia quinquegona Bl.) in exposureto different light intensities was investigated. The organic free radical scavenging capacity (ORSC) expressed as the percentage of decreasing DPPH· was 16%-59% (pot seedlings) or 48%-88% (young trees in the forest). The highest ORSC was observed in plants grown under natural light, and the ORSC reduced with the decreasing light intensity. Similar trend was observed through the assay of inhibition to linoleic acid oxidation. The ORSC of P. rufra, an understory shrub, was more sensitive to the change of light intensity. A linear relationship was found between ORSC and AsA (ascorbic acid) content (r=0.92) or the absorption around the wavelength of 204-227 nm. It is proposed that ORSC of leaf was regulated by incident light intensity, and the contents of AsA and, flavonoid phenolics might be the important components contributed to ORSC and total antioxidant activity of leaves. The increasing ORSC is likely to be a protective strategy of plant in response to strong light.     

不同遮阴环境下木奶果幼苗生长与生理生化的响应

木奶果是一种在幼苗期和成熟期对光适应性不同的热带乔木树种。研究不同遮阴环境下木奶果幼苗的生长及生理响应机制,以明确木奶果幼苗生长的适宜光照环境范围,对木奶果的苗木栽培及生态应用意义重大。本试验设置了5个处理,即CK(无遮阴),S3(遮光率45.3%)、S4(遮光率69.2%)、S6(遮光率80.0%)和S8(遮光率90.2%),观测停扣山和谢鞋山种源的木奶果幼苗4个月后的生长生理变化情况。结果显示:随着遮阴强度的加大,木奶果幼苗的叶面积与光合色素含量一直上升;叶绿素a/b值和过氧化氢酶(CAT)活性一直下降;丙二醛含量在S6前先呈下降趋势,而后稍有上升;株高和地径增长量先升后降,相对电导率、脯氨酸(Pro)与可溶性糖(Ss)含量则表现为先降后升。强光环境下,木奶果幼苗通过增加类胡萝卜素相对含量与CAT活性,以减缓膜脂过氧化损害;弱光环境下,木奶果幼苗通过增加叶面积与光合色素含量提高光能利用率。Pro与Ss则作为综合调节物,调节渗透压,以减轻强光与弱光带来的细胞膜胁迫压力。其中,停扣山与谢鞋山种源分别在S6与S4处理下Pro与Ss含量达最低值且株高与地径增长量达最高值。表明幼苗期的木奶果具有阴生植物的特性,强光或重度遮阴都会在一定程度上抑制其生长。停扣山种源木奶果幼苗比谢鞋山种源更耐阴,反映了其种源地长期光强环境差异的影响。     

岳桦幼苗光合特性和非结构性碳水化合物积累对干旱胁迫的响应

以长白山林线树种岳桦为对象,利用生长控制试验进行干旱处理,研究干旱对岳桦幼苗光合特性及非结构性碳水化合物(NSC)积累的影响.结果表明:干旱显著降低了岳桦幼苗的净光合速率和气孔导度,提高了其水分利用效率;干旱显著增加了岳桦幼苗叶、皮、干和根中的可溶性糖和总NSC的含量,但显著降低了淀粉含量;随着干旱的持续,叶片的气孔导...     

基于天然更新性能筛选海南岛木麻黄海防林混交树种

基于对海南木麻黄(Casuarina equisetifolia L.)海防林天然更新情况的实地调查,采用更新数量、更新分布范围和更新结构3项单目标评价方法和熵权综合评价方法,对不同树种在木麻黄林下的天然更新性能进行评价和排序,据此筛选出适宜在木麻黄林下天然更新的树种。结果显示,更新能力较强的树种有:乔木树种潺槁木姜子(Litsea glutinosa(Lour.)C.B.Rob.)、大叶相思(Acacia auriculiformis A.Cunn.ex Benth)、苦楝(Melia azedarace L.)和鹊肾树(Streblus asper Lour.);小乔木鸦胆子(Brucea javanica(Linn.)Merr.)、露兜树(Pandanus tectorius Sol.)和暗罗(Polyalthia suberosa(Roxb.)Thw.);灌木酒饼簕(Atalantia buxifolia(Poir.)Oliv.)、调料九里香(Murraya koenigii(L.)Spreng.)、刺篱木(Flacourtia indica(Burm.F.)Merr.)和基及树(Carmona microphylla(lam.)G.Don)。具有一定更新潜力的树种有:乔木树种榄仁树(Terminalia catappa L.)、红厚壳(Calophyllum inophyllum L.)等;小乔木粗糠柴(Mallotus philippensis(Lam.)Muell.Arg.)、八脉臭黄荆(Premna octonervia Merr.et Metc.)等;灌木苦郎树(Clerodendrum inerme(L.)Gaertn.)、九节(Psychotria rubra(Lour.)Poir.)等。小乔木和灌木是海防林的伴生树种,适当保留和种植可提高木麻黄林的物种多样性和层次结构。选用天然更新良好的树种与木麻黄混交,最终可实现海防林由人工林向“近自然”林的转化。     

紫外线-B辐射与3种植物幼苗的光合作用——光合作用对紫外线-B敏感性的比较

紫外线 - B辐射降低豌豆、大豆和黄瓜 3种植物幼苗的净光合作用速率 ( Pn)和表观量子效率 ( AQE) ,Pn和 AQE的减少幅度随紫外线 - B辐射时间的延长逐渐增大。 3种植物的光合作用对紫外线 - B辐射的敏感性依次为 :豌豆 >黄瓜 >大豆 ,光合作用光抑制的发生程度与光合作用对 UV- B辐射敏感性有内在联系。定量分析显示 ,光合作用光抑制的发生程度随UV- B辐射时间增加 ,是 UV- B辐射剂量的累积效应。     

Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation

Seedlings of two late-successional tropical rainforest tree species, Tetragastris panamensis (Engler) O. Kuntze and Calophyllum longifolium (Willd.), were field grown for 3-4 months at an open site near Panama City (9 degrees N), Panama, under plastic films that either transmitted or excluded most solar UV-B radiation. Experiments were designed to test whether leaves developing under bright sunlight with strongly reduced UV-B are capable of acclimating to near-ambient UV-B conditions. Leaves of T. panamensis that developed under near-ambient UV-B contained higher amounts of UV-absorbing substances than leaves of seedlings grown under reduced UV-B. Photosynthetic pigment composition, content of alpha-tocopherol, CO(2) assimilation, potential photosystem II (PSII) efficiency (evaluated by F(v)/F(m) ratios) and growth of T. panamensis and C. longifolium did not differ between seedlings developed under near-ambient and reduced solar UV-B. When seedlings were transferred from the reduced UV-B treatment to the near-ambient UV-B treatment, a pronounced inhibition of photosynthetic capacity was observed initially in both species. UV-B-mediated inhibition of photosynthetic capacity nearly fully recovered within 1 week of the transfer in C. longifolium, whereas in T. panamensis an about 35% reduced capacity of CO(2) uptake was maintained. A marked increase in UV-absorbing substances was observed in foliage of transferred T. panamensis seedlings. Both species exhibited enhanced mid-day photoinhibition of PSII immediately after being transferred from the reduced UV-B to the near-ambient UV-B treatment. This effect was fully reversible within 1d in T. panamensis and within a few days in C. longifolium. The data show that leaves of these tropical tree seedlings, when developing in full-spectrum sunlight, are effectively protected against high solar UV-B radiation. In contrast, leaves developing under conditions of low UV-B lacked sufficient UV protection. They experienced a decline in photosynthetic competence when suddenly exposed to near-ambient UV-B levels, but exhibited pronounced acclimative responses.     

木犀属新资料(Ⅱ)

运用经典分类方法,在对木犀属进行系统研究的基础上,归并了总状桂花Osmanthus racemosus X.H.Song,将其作为厚叶木犀O.marginatus(Champ.ex Benth.)Hemsl.var.pachyphyllus(H.T.Chang)R.L.Lu的一个新异名;将大果桂花O.macrocarpus P.Y.Bai转移到野桂花O.yunnanensis(Franchet)P.S.Green下作为其异名,从而给出了木犀属的两个新异名。     

不同光质对桑树幼苗生长和光合特性的影响

光质可影响植物光合特性、形态以及生理过程。本试验研究了不同光质(白光W、红光R、红蓝混合光RB、蓝光B)对桑树植株生长、形态和光合作用的影响。结果表明:与白光对照相比,红光、蓝光和红蓝混合光处理下植株的生长、干物质积累受到抑制;红光处理下植株的株高、叶面积显著高于白光、红蓝混合光、蓝光处理;而白光、红蓝混合光、蓝光处理下植株的LMA、叶绿素a/b比值、可溶性蛋白含量、蔗糖、淀粉含量和叶片总N含量显著高于红光处理;红蓝混合光处理下植株的Pn、Gs、ΦPSⅡ与白光处理相近,红光、蓝光处理下植株的Pn、ΦPSⅡ低于白光、红蓝混合光处理,同时红光、红蓝混合光、蓝光处理下植株的抗氧化酶活性高于白光处理,而MDA含量低于白光处理;红光处理下植株的叶片厚度、栅栏组织和海绵组织厚度显著小于白光处理。因此,一定比例的红蓝混合光可以使桑树植株的生长、光合特性、生理特征和叶片解剖结构与白光下生长植株相近,并减少单质红光、单质蓝光对植株生长发育的不利影响。     

短期增强UV-B辐射对青榨槭幼苗生理特性的影响

在中国科学院茂县生态站选择2年生青榨槭幼苗进行室外盆栽实验,以人工增强0.27 W·m^-2(7.7kJ·m^-2·d^-1)的UV-B辐射剂量,研究模拟当地平流层臭氧削减1%时近地面太阳UV-B的增强对木本植物幼苗生理生态适应性的影响.处理0 d后,移除UV-B处理装置,就地测定气体交换参数和叶绿素荧光参数,并取样测定叶绿素及UV吸收物质含量.结果表明,增强UV-B辐射显著降低了青榨槭幼苗叶片最大净光合速率P_max(对照为6.214,处理为4.42),显著增加叶片暗呼吸速率Rd(对照为0.413,处理为1.29)和光补偿点LCP(对照为21.629,处理为9.861),但对表观量子速率a(对照为0.021,处理为0.032)影响不明显;它降低青榨槭幼苗每日净光合速率和水分利用效率,以及原初光化学效率(F_v/F_m)和实际光化学量子产量(ΦPS∏).此外,增强UV-B辐射使叶片叶绿素a、b含量降低(对照为16.23,.39,处理为13.17,4.93),但对叶绿素b含量影响未达显著水平.增强UV-B处理降低了青榨槭幼苗UV吸收物质含量(对照为0.87,处理为0.79).光合指标、叶绿素荧光指标和叶绿素含量的变化有较好的一致性,表明增强UV-B对青榨槭幼苗的光合作用可能有一定的抑制作用.     

氯化钠胁迫对嫁接茄子生长、抗氧化酶活性和活性氧代谢的影响

以日本引进的茄子设施栽培专用耐盐品种‘Torvum Vigor’为砧木,栽培品种‘苏崎茄’为接穗,在营养液栽培条件下,对80 mmol·L^-1 NaCl胁迫下茄子嫁接苗和自根苗的光合特性、叶片抗氧化酶活性、活性氧代谢进行了比较.结果表明：NaCl胁迫下,茄子嫁接苗的干质量、叶绿素含量和光合速率分别比苏崎茄自根苗高67。8％、8。8％和31。1％,均有显著差异;抗氧化酶活性均显著高于苏崎茄自根苗,而O₂^-_·生成速率、H₂O₂和MDA含量则显著低于苏崎茄自根苗.NaCl胁迫明显降低了叶片叶绿素含量和光合速率,显著增加了O₂^-_·生成速率、H₂O₂和MDA含量,但嫁接苗受NaCl胁迫的影响小于苏崎茄自根苗,嫁接苗较强的耐盐性与NaCl胁迫下较高的抗氧化酶活性和较低的氧化损伤有关.     

木犀属新资料(Ⅱ)

运用经典分类方法,在对木犀属进行系统研究的基础上,归并了总状桂花Osmanthus racemosus X.H.Song,将其作为厚叶木犀O.marginatus(Champ.ex Benth.)Hemsl.var.pachyphyllus(H.T.Chang)R.L.Lu的一个新异名;将大果桂花O.macrocarpus P.Y.Bai转移到野桂花O.yunnanensis(Franchet)P.S.Green下作为其异名,从而给出了木犀属的两个新异名。     

遮光条件下不同种源土沉香幼苗的光合特性与生长速率分析

以3个来源于广东茂名的土沉香[ Aquilaria sinensis (Lour.) Spreng.]种源(大白、小白和大黄)和1个来源于云南的土沉香种源的1年生幼苗为研究对象,对不同遮光条件下[相对光强100％(对照,自然光强)、50％、25％和5％]4个种源幼苗叶片的净光合速率(Pn)的光响应和CO2响应曲线、光合和气体交换参数、叶绿素含量和叶绿素a/b( Chla/b)值进行了分析,并比较了4个种源幼苗的相对生长速率(RGR).结果表明:4个种源的Pn均随光合光量子通量密度的增加而上升,且对照组各种源的Pn值均明显高于各处理组;4个种源的Pn值均随胞间CO2浓度的升高或相对光强的增大逐渐提高.随相对光强的降低,4个种源的最大光合速率、光补偿点、光饱和点、暗呼吸速率、最大电子传递速率、最大羧化速率和磷酸丙糖利用速率均下降或显著下降(P＜0.05),而表观量子效率则略有升高.在相对光强100％ ～ 25％条件下,随相对光强降低,4个种源的叶绿素含量显著提高、Chla/b值显著减小;大白和小白种源的RGR逐渐增大,大黄种源的RGR差异不显著,而云南种源的RGR显著减小.而在相对光强5％条件下,大黄和云南种源的叶绿素含量显著降低,Chla/b值显著增大,RGR显著减小;大白和小白种源幼苗全部死亡.由种源间的比较可见:4个种源的各项光合参数以及叶绿素含量、相对生长速率均有一定的差异,其中云南种源的各项指标总体上均最低.综合来看,土沉香为半阳生植物,对不同的光环境表现出相对较强的适应性.     

田间增加紫外线（UV）辐射对大豆幼苗生长和光合作用的影响

 两个增加的UV(UV-AB,280～400nm)辐射强度分别相当于大气臭氧减少3.6％和5.1％时增加的UV-B辐射。UV辐射增强明显降低大豆的株高、叶面积、干重、水分含量和叶绿素含量,大豆生长受抑程度随人工UV光源照射时间和强度增加而增强,是增加UV辐射剂量的累积效应,叶绿素b的降幅大于叶绿素a,表明UV辐射对大豆幼苗捕光色素的破坏较严重。同时,增加UV辐射还使大豆幼苗的表观光合速率、蒸腾速率、水分利用效率、气孔导度下降,作用效果与辐射强度正相关。与生长等比较,UV辐射条件下,冠／根比值减少幅度不大。分析认为,大豆幼苗生长和光合能力的下降可以使植物避免或减轻UV辐射的进一步伤害,对植物适应UV辐射有利。     

Effect of 2,4-dichlorophenoxyacetic acid on the structure and function of developing chloroplasts

Dark-grown radish seedlings (Raphanus sativus L.) were sprayed with 10^-3 mol·l^-1 2,4-dichlorophenoxyacetic acid and then were exposed to a 14:10 light: dark cycle. Cotyledon samples from these seedlings and unsprayed controls were taken for electron microscopy, chlorophyll determinations, and photosynthetic rate measurements at regular intervals for 72 h. A normal development of etioplasts to chloroplasts with formation of typical grana-fret work system was observed in the control cotyledons. The chloroplasts in the 2,4-D-treated cotyledons showed changes in the organization of the grana thylakoids; these thylakoids being more appressed to each other than in the controls. The chlorophyll content of treated plants was less than that of controls but the rate of chlorophyll biosynthesis was unaffected. The photosynthetic rate/mg chlorophyll was considerably higher for treated plants suggesting that 2,4-D treatment resulted in decreased size of the photosynthetic unit.     

Non-geotropic Growth Curvatures in the Striga Radicle

When seedlings of the root parasite Striga asiatica Benth. (=S. lutea Lour.) are grown in0 the absence of the host the radiclegrows to a length of about 4 mm. On emergence the radicle showsa strong curvature which is brought about by a failure of cellextension on one side. The inhibited cells generally remainun-extended throughout the life of the seedling. Neither thesodium salt of indole-3-acetic acid nor Inhibitor-ß(which is present in the seeds), induced permanent inhibitionsto the radicle cells when applied externally, as did the endogenouscurvature factor. 2: 3: 5-tri-iodobenzoic acid reduced curvatureby promoting extension of the normally inhibited cells.     

Effects of solar ultraviolet-B radiation,temperature and CO2 on growth and physiology of sunflower and maize seedlings

The effects of solar UV-B radiation, in combination with elevated temperature (4 °C ) and CO₂ (680 L L^-1 concentration, on sunflower and maize seedlings were studied from May to August in 1991 at the research station Quinta de São Pedro in Portugal (38.7°N). The ambient solar radiation of Portugal was reduced to levels of Central European latitudes by using the ozone filter technique. This radiation served as control, while the ambient solar radiation of Portugal was to simulate intense UV-B treatment (+30%). All plants were grown up to 18 days in 4 climate controlled growth chambers simulating a daily course of temperature with T_max=28 °C or 32 °C , resp., and ambient CO₂ concentrations (340 L L^-1); in one chamber the CO₂ concentration was twice as high (680 L L^-1). Under intense UV-B and at 28 °C (T_max) all growth parameters (height, leaf area, fresh and dry weight, stem elongation rate, relative growth rate) of sunflower and maize seedlings were reduced down to 35% as compared to controls. An increase in growing temperature by 4 °C , alone or in combination with doubled CO₂, compensated or even overcompensated the UV-B effect so that the treated plants were comparable to controls. Chlorophyll content, on a leaf area basis, increased under intense UV-B radiation. This increase was compensated by lower leaf areas, resulting in comparable chlorophyll contents. Similar to growth, also the net photosynthetic rates of sunflower and maize seedlings were reduced down to 29% by intense UV-B calculated on a chlorophyll basis. This reduction was compensated by an increased temperature. Doubling of CO₂ concentration had effects only on sunflower seedlings in which the photosynthetic rates were higher than in the controls. Dark respiration rates of the seedlings were not influenced by any experimental condition. Transpiration and water use efficiency (wue) were not influenced by intense UV-B. Higher temperatures led to higher transpiration rates and lower water use efficiencies, resp.. Doubling of CO₂ reduced the transpiration rate drastically while for wue maximum values were recorded.     

穗状狐尾藻与不同生长期苦草种间竞争研究

水生植物之间的竞争作用在水体生态系统恢复过程中具有重要作用。本研究采用取代系列实验方法,对穗状狐尾藻(Myriophyllum spicatum L.)与不同生长期(幼苗期和成株期)苦草(Vallisneria natans(Lour.)Hara)的种间竞争进行了研究。结果显示,对于不同生长期的苦草,穗状狐尾藻均具有较强的竞争优势,成株期苦草的竞争能力强于其幼苗期;苦草成株组中的穗状狐尾藻平均株高比苦草幼苗组中的穗状狐尾藻平均株高增加了128.6%(P0.05),但苦草成株组中的穗状狐尾藻植株平均干重比苦草幼苗组中的穗状狐尾藻植株平均干重降低了62.8%(P0.05);苦草幼苗组中的穗状狐尾藻分枝较多、株丛大,对苦草幼苗形成了较大的遮光作用;苦草成株组中的穗状狐尾藻分枝少、植株较长,顶端漂浮于水面生长,表明受苦草的种间竞争压力增大,但仍小于穗状狐尾藻的种内竞争;另外,苦草幼苗组中的苦草根长比苦草成株组中的苦草根长平均长28.6%(P0.05),表明在与穗状狐尾藻竞争过程中,苦草幼苗更趋于竞争地下资源。本研究结果说明穗状狐尾藻竞争能力强于苦草,苦草幼苗受穗状狐尾藻的竞争影响较大。     

Elevated growth temperatures reduce the carbon gain of black spruce [Picea mariana (Mill.) B.S.P.]

We explored the effect of high‐growth temperatures on a dominant North American boreal tree, black spruce [Picea mariana (Mill.) B.S.P.]. In 2004 and 2005, we grew black spruce at either 22 °C/16 °C day/night temperatures [low temperature (LT)] or 30°/24 °C [high temperature (HT)] and determined how temperature affected growth, leaf morphology, photosynthesis, respiration and thermotolerance. HT spruce were 20% shorter, 58% lighter, and had a 58% lower root : shoot ratio than LT trees. Mortality was negligible in the LT treatment, but up to 14% of HT seedlings died by the end of the growing season. HT seedlings had a higher photosynthetic temperature optimum, but net photosynthesis at growth temperatures was 19–35% lower in HT than LT trees. HT seedlings had both a lower apparent maximum ribulose‐1,5‐bisphosphate carboxylation capacity (V_cmax) and a lower apparent maximum electron transport rate (J_max) than LT trees, indicating reduced allocation to photosynthetic components. Consistently, HT needles had 26% lower leaf nitrogen content than LT needles. At each measurement temperature, HT seedlings had 20–25% lower respiration rates than LT trees; however, this did not compensate for reduced photosynthetic rates at growth temperature, leading to a greater ratio of dark respiration to net carbon dioxide assimilation rate in HT trees. HT needles had 16% lower concentrations of soluble sugars than LT needles, but similar starch content. Growth at high temperatures increased the thermotolerance of black spruce. HT trees showed less PSII inhibition than LT seedlings and no increase in electrolyte leakage when briefly exposed to 40–57 °C. While trees that develop at high temperatures have enhanced tolerance for brief, extreme heat events, the reduction in root allocation indicates that seedlings will be more susceptible to episodic soil drying and less competitive for belowground resources in future climates of the boreal region.