紫外辐射增强对4个甘蔗割手密无性系根际真菌数量和优势种群的影响

采用大田试验方法,研究了模拟紫外辐射(UV-B,280 nm～310 nm)增强对4个UV-B辐射敏感性不同的割手密无性系根际真菌数量和优势种群的影响.结果表明:UV-B辐射增强不改变割手密根际真菌的数量在分蘖期最大、幼苗期次之、伸长期和成熟期较少的规律性:UV-B辐射增强条件下,割手密耐性无性系根际真菌数量显著增加,并显著多于敏感无性系,但UV-B辐射使割手密无性系根际真菌的优势种群组成减少,优势种群以青霉属真菌为主.     

不同氮供应下增强UV-B辐射对谷子叶片重要生理指标的影响

以谷子(Setaria italica(L.)Beauv.)为研究材料,从拔节期开始持续浇灌1.88、15mmol·L-12种氮供应水平营养液,从抽穗期开始对材料进行增强UV-B辐射处理(14.7μW·cm-2),研究了谷子叶片中总叶绿素、可溶性物质及紫外吸收物质的含量在开花期期间的变化。结果表明:与较高氮供应水平相比,无论是否进行增强UV-B辐射,较低氮供应水平明显降低了谷子叶中总叶绿素、可溶性蛋白的含量,但提高了其紫外吸收物质的含量;与较低氮供应水平相比,较高氮供应水平下的谷子叶中总叶绿素含量在开花期初期和中期,可溶性蛋白含量在开花期中期对增强UV-B辐射处理更敏感;氮供应水平虽然对开花期中期至末期的谷子叶片可溶性糖含量有显著影响,但在整个增强UV-B辐射处理期间,该指标对增强UV-B辐射并不敏感。上述结果表明,较低氮供应水平可促进谷子叶片在开花期期间紫外吸收物质的积累,有利于增强其抵抗UV-B辐射能力,但仍应寻求一个合理范围的氮供应水平,以平衡谷子生殖生长和提高对UV-B辐射抗性的需求。     

UV-B辐射对报春花的生理生化效应

通过室内模拟试验,研究不同强度的UV-B辐射(10μW/cm2和20μW/cm2)对报春花生理代谢的影响,结果表明:(1)增强UV-B辐射下,报春花叶片叶绿素含量降低,且随UV-B辐射时间的延长,降低程度加大;(2)随UV-B辐射强度的增加,叶片质膜透性增加;(3)叶片类黄酮含量随着UV-B辐射强度的增加而增加,在辐射至40 d时,叶片类黄酮含量达到最大值;(4)增强UV-B辐射下,报春花花瓣中花青素含量增加.     

不同小麦品种对UV-B辐射增强响应的生理特性差异

研究了大田条件下模拟增强UV-B辐射（500 KJ·m^-2,相当于昆明地区臭氧层减少20%）对10个小麦品种生理指标的影响以及小麦对UV B辐射响应的种内差异.结果表明,10个供试小麦品种中有6个品种的叶绿素含量显著下降,叶绿素a降低的程度大于叶绿素b,从而导致叶绿素a/b的比率下降.UV-B对小麦叶片内MDA和类黄酮的影响也具有种内差异,有5个品种的MDA含量显著上升, 2个品种的MDA含量显著下降;4个品种的类黄酮含量显著增加,2个品种的类黄酮含量显著减少.叶绿素和类黄酮含量变化与MDA含量均呈显著负相关关系,类黄酮与小麦UV-B抗性之间存在密切联系.     

滤减UV-B辐射对烟叶可溶性蛋白、光合色素和类黄酮的影响

在云南玉溪烟区种植烤烟海拔最高(1806.0m)的通海县,通过盆栽烤烟K326试验,研究了在滤减自然的太阳UV-B辐射强度25%、50%和65%条件下,UV-B辐射对烟叶发育过程中可溶性蛋白、光合色素和类黄酮的影响。结果表明:随叶龄增加,可溶性蛋白含量下降,光合色素降解,类黄酮在老叶中积累,蛋白质在生理成熟期对UV-B辐射最敏感。与对照相比,减弱UV-B辐射处理降低了烟叶类黄酮和可溶性蛋白含量,但光合色素含量上升;较低的UV-B辐射降低了叶绿素的降解速度。结果从一侧面说明UV-B辐射对烟叶蛋白质的合成是有益的,类黄酮和叶绿素的变化是对UV-B辐射变化的适应性反应,类黄酮与蛋白质之间可能存在一定的偶联关系。     

滤减UV B辐射对烟叶可溶性蛋白、〖HJ*3〗〖HJ*2〗光合色素和类黄酮的影响

在云南玉溪烟区种植烤烟海拔最高(1806.0m)的通海县,通过盆栽烤烟K326试验,研究了在滤减自然的太阳UV-B辐射强度25%、50%和65%条件下,UV-B辐射对烟叶发育过程中可溶性蛋白、光合色素和类黄酮的影响。结果表明:随叶龄增加,可溶性蛋白含量下降,光合色素降解,类黄酮在老叶中积累,蛋白质在生理成熟期对UV-B辐射最敏感。与对照相比,减弱UV-B辐射处理降低了烟叶类黄酮和可溶性蛋白含量,但光合色素含量上升;较低的UV-B辐射降低了叶绿素的降解速度。结果从一侧面说明UV-B辐射对烟叶蛋白质的合成是有益的,类黄酮和叶绿素的变化是对UV-B辐射变化的适应性反应,类黄酮与蛋白质之间可能存在一定的偶联关系。     

UV-B辐射胁迫下杨梅幼苗的高光谱响应

设置UV-B滤光减弱、UV-B辐射增强和自然光(对照)3组模拟大田试验,比较了不同UV-B辐射处理下,亚热带典型木本植物杨梅幼苗的叶绿素含量、光谱反射率及光谱特征参数,研究UV-B辐射变化对亚热带森林树种的影响.结果表明:增强UV-B辐射可降低杨梅幼苗的叶绿素含量,而降低辐射则会显著促进叶绿素的增加,并且这种胁迫反应于光谱反射率中.3种不同梯度UV-B辐射作用下,可见光部分光谱反射率间的差异主要集中在绿光反射峰及红边附近,同时红边所在波长位置“红移”.UV-B辐射对杨梅的胁迫在时间上具有积累性.用反高斯模型参数R0、λ0、λp、Rs、6指示杨梅受UV-B胁迫,以Rs最显著.不同UV-B辐射水平下植物叶片光谱反射率上的差异,可通过较窄波段光谱反射率或特定波长光谱反射率所构建的植被指数加以有效区分.     

异质性UV-B辐射下NO在活血丹光合特性中的作用研究

我们前期研究发现异质性UV-B辐射下NO参与克隆植物紫外吸收物和抗氧化酶活力的整合过程。光合作用在植物生长过程中十分重要,但异质性UV-B辐射下NO在克隆植物光合特性中是否发挥作用仍不清楚。本研究模拟同质(克隆分株片段均处于自然背景辐射)和异质(克隆分株一端处于自然背景辐射,另一端处于补加的UV-B辐射)UV-B辐射,以克隆植物活血丹为材料,研究异质性UV-B辐射下,NO清除剂在克隆整合提高活血丹气体交换参数和叶绿素含量中的作用。结果表明:与处于同质UV-B辐射环境相比,异质UV-B辐射下连接处理中的活血丹UV-B辐射端气体交换参数和叶绿素含量显著增加,但NO清除剂改变了这一趋势,说明NO作为信号分子在克隆植物生理整合提高了活血丹光合生理特性中发挥重要作用,有助于全面认识UV-B辐射在克隆植物生长调控中的作用,为了解异质性UV-B环境下克隆植物生理整合的机理提供理论依据。     

增强UV-B辐射对作物生理代谢、DNA和蛋白质的影响研究进展

大气平流层的臭氧层逐渐破坏导致太阳辐射中抵达地球表面的UV-B辐射增加,对作物产生不同程度的影响.本文讨论了UV-B辐射增强对作物生理代谢、DNA损伤和蛋白质含量的影响.UV-B辐射增强,作物叶片类黄酮含量增加、叶绿素含量降低、光合作用减弱,同时UV-B辐射诱致基因活性变化,导致DNA损伤和蛋白质含量的改变.     

UV-B辐射对仙客来的生理效应

通过室内模拟试验,研究了不同强度UV-B辐射(10μW/cm2和20μW/cm2)对仙客来(Cyclamen persicum Mill)生理的影响。结果表明:(1)UV-B辐射的增加对仙客来叶片光合色素的含量具有影响;(2)叶片质膜透性随UV-B辐射强度的增加而增加,随UV-B辐射时间的延长而增加;(3)叶片类黄酮含量随UV-B辐射强度的增加而增加,且在40d时达到最大值;(4)增强UV-B辐射下,仙客来花瓣中的花青素含量增加。     

增强UV-B辐射和氮对谷子叶光合色素及非酶促保护物质的影响

以谷子(Setaria italica(L)Beauv.)为对象,从拔节期开始持续给予低氮(1.875 mmol/L)和高氮(15 mmol/L)两种氮供应条件并从抽穗期开始进行26 d两种强度(4.29、7.12 kJ·m-2·d-1)的增强UV-B辐射处理,研究了谷子叶中光合色素含量、类黄酮含量和苯丙氨酸解氨酶(PAL)活性的变化.结果表明:与高氮供应条件相比,低氮供应条件明显降低了谷子叶中光合色素含量但提高了类胡萝卜素/叶绿素含量比值;在开花期中段和灌浆期中段,高氮供应条件下谷子叶中光合色素含量对增强UV-B辐射比低氮供应条件下的谷子更敏感.从灌浆期开始到处理结束,两种影响因子对谷子叶中类黄酮含量均有显著影响,增强UV-B辐射导致谷子叶中类黄酮含量逐渐升高,且相同增强UV-B辐射强度下低氮供应条件下的谷子叶中类黄酮含量明显高于高氮供应条件下的谷子.谷子叶中PAL活性对两种影响因子的响应较类黄酮含量更加敏感,低氮供应条件使谷子叶中PAL活性明显提高.结合上述指标的相关性分析结果可知,低氮供应条件加强了处于繁殖期主要阶段的谷子叶中类黄酮的积累,并使谷子叶中的类胡萝卜素/叶绿素含量比值明显提高,进而有助于维持谷子叶中光合色素含量在增强UV-B辐射条件下的相对稳定性,对植株抵抗UV-B辐射伤害有利.     

自然条件下滤减UV-B辐射对烤烟光合色素含量的影响

在自然环境中,以烟草栽培品种K326为材料,通过覆盖不同透明薄膜滤减UV—B辐射,研究100％（CK）、75％（T1）、50％（T2）、35％（T3）UV—B辐射透过率处理下,不同强度UV—B辐射对烟草光合色素含量的影响。结果表明：烤烟三类光合色素对UV—B辐射有不同响应。类胡萝卜素对UV—B辐射响应较敏感。成熟初期,类胡萝卜素含量与UV—B辐射强度变化具有较好的正相关性,而chl a和chl b含量基本与UV—B辐射强度呈反向变化关系。成熟后期,由于UV—B辐射累积效应,光合色素含量变化没有明显规律。现蕾期至成熟采烤烟初期,chl a：chl b与UV—B辐射的反向变化关系较明显,后期则无明显规律,其含量的下降与UV—B辐射的累积效应有关。     

杂种杨无性系的光系统Ⅱ放氧活性、光合色素及叶绿体超微结构对光胁迫的响应

 用氧电极仪、红外CO2气体分析仪及叶绿素荧光仪,结合透射电镜技术对几个杂种杨无性系在光胁迫下的光系统Ⅱ活性、光合色素及叶绿体超微结构进行了测定。随着预处理光强的增加,各无性系叶片的净光合速率和光系统Ⅱ放氧活性明显下降。二倍体无性系B11的光系统Ⅱ最大光化学效率（Fv/Fm）及实际光化学效率［(Fm′-F)/Fm′］高于两个三倍体无性系B346和B342。强光下三倍体无性系B346的非光化学淬灭远高于B342和二倍体无性系B11。叶绿素含量和光合速率没有明显的线性关系,叶绿素a/b含量在自然光胁迫下存在季节变化,受强光胁迫2个三倍体无性系的叶绿素a/b增大。预处理光强PFD超过3 000 μmol photons·m-2·s-1,各无性系的基粒类囊体片层结构遭到破坏,但二倍体无性系的类囊体片层结构受破坏程度较三倍体无性系轻。叶绿体蛋白合成抑制剂（硫酸链霉素,SM）可加剧叶绿体超微结构的破坏。     

UV-B辐射增强对两种不同抗性水稻叶片光合生理及超显微结构的影响

在UV-B辐射增强条件下,研究了两个不同水稻品种叶片光合作用系统的变化。结果表明：（1）UV-B辐射胁迫使两个水稻品种叶片总叶绿素含量,叶绿素a与叶绿素b（Chla／Chlb）比值下降,叶绿素a荧光诱导动力学参数改变,光系统Ⅱ活性受抑制,光合作用效率降低,其中Dular受抑制的程度较Lemont大。（2）利用扫描电镜（SEM）和透射电镜（TEM）进一步研究表明,UV-B辐射胁迫使水稻叶片气孔器受破坏,叶绿体结构变形,基粒片层排列稀疏紊乱,两个供试品种结构上受破坏的程度与它们光合生理受抑制的程度一致。（3）叶片边缘受破坏的程度较主脉两侧轻,这可能与硅质乳突密度较大有关。（4）两个供试品种叶片表面主脉两侧的硅质乳突数量及其受UV-B辐射影响的特性存在明显的差异,Lemont叶表面的乳突分布密度较大,且在UV-B辐射胁迫下有增加的趋势,而Dular则相反。这说明硅质体的累积特性可能是水稻对UV-B辐射胁迫的适应机制之一。     

Intraspecific differences in physiological response of 20 wheat cultivars to enhanced ultraviolet-B radiation under field conditions

Field studies were conducted to determine the potential for alterations in physiology and the intraspecific variation in sensitivity of 20 wheat (Triticum aestivum) cultivars to enhanced ultraviolet-B (UV-B, 280-315 nm) radiation. The supplemental UV-B radiation was 5 kJ m(-2), simulating a depletion of 20% stratospheric ozone. Out of 20 wheat cultivars (from South China, North China and Mexico) tested, 13 showed significant changes in total chlorophyll content. In most of these sensitive species, chlorophyll a content was strongly reduced, and chlorophyll b content decreased in a lesser extent, leading to a decrease in chlorophyll a/b ratio. However, some species had an increased chlorophyll a/b ratio under enhanced UV-B. The effect of UV-B on flavonoid content also showed intraspecific differences, a significant increase for one cultivar, decreases in 12 cultivars and no effect on the other seven cultivars. Superoxide dismutase (SOD) activity of five cultivars was significantly increased, and that of six cultivars significantly decreased. Membrane permeability of 12 cultivars significantly increased, while only that of Dali 905 was significantly decreased. Malonaldehyde (MDA) contents of eight cultivars were increased significantly, while that of three cultivars was significantly decreased. Although large intraspecific differences were found for the different parameters measured, there was no clear correlation between them under UV-B radiation.     

Response of photosynthesis to high light and drought for Arabidopsis thaliana grown under a UV-B enhanced light regime

Arabidopsis thaliana grown in a light regime that included ultraviolet-B (UV-B) radiation (6 kJ m⁻² d⁻¹) had similar light-saturated photosynthetic rates but up to 50% lower stomatal conductance rates, as compared to plants grown without UV-B radiation. Growth responses of Arabidopsis to UV-B radiation included lower leaf area (25%) and biomass (10%) and higher UV-B absorbing compounds (30%) and chlorophyll content (52%). Lower stomatal conductance rates for plants grown with UV-B radiation were, in part, due to lower stomatal density on the adaxial surface. Plants grown with UV-B radiation had more capacity to down regulate photochemical efficiency of photosystem II (PSII) as shown by up to 25% lower φ_PSII and 30% higher non-photochemical quenching of chlorophyll fluorescence under saturating light. These contributed to a smaller reduction in the maximum photochemical efficiency of PSII (F _v/F _m), greater dark-recovery of F _v/F _m, and higher light-saturated carbon assimilation and stomatal conductance and transpiration rates after a four-hour high light treatment for plants grown with UV-B radiation. Plants grown with UV-B were more tolerant to a 12 day drought treatment than plants grown without UV-B as indicated by two times higher photosynthetic rates and 12% higher relative water content. UV-B-grown plants also had three times higher proline content. Higher tolerance to drought stress for Arabidopsis plants grown under UV-B radiation may be attributed to both increased proline content and decreased stomatal conductance. Growth of Arabidopsis in a UV-B-enhanced light regime increased tolerance to high light exposure and drought stress.     

Responses in ion leakage of wild sugarcane (Saccharum spontaneum L.) clones to enhanced ultraviolet-B radiation under field conditions

Field studies were conducted to determine the potential for alterations in ion leakage and the intraspecific variation in ion leakage sensitivity of 20 wild sugarcane clones (Saccharum spontaneum L.) to enhanced ultraviolet-B (UV-B, 280–315nm) radiation in two consecutive years. The clones were collected from original sites with different altitude (from 0 to 1650 m) and latitude (from 18–37 °N). The supplemental UV-B radiation was 5.00 kJ m⁻², simulating a depletion of 20 % stratospheric ozone. Across all clones tested in the present study, a significant change (P<0.01 or 0.05) in ion leakage for 11 in tillering, 14 in elongation and 15 in flowering in 2003, and for 9 in tillering, 5 in elongation and 5 in floweing in 2004 were observed. In general, intraspecific responses of ion leakage of wild sugarcane clones to enhanced UV-B radiation existed under field conditions for two consecutive years, although intraspecific difference in 2003 was more obvious than that in 2004. Wild sugarcane clones originating from lower latitude or high elevation were not necessarily the more tolerant to enhanced UV-B radiation.     

Seasonal accumulation of ultraviolet-B screening pigments in needles of Norway spruce (Picea abies (L.) Karst.)

Conifer needles are highly effective in screening ultraviolet-B radiation (280–320 nm). This ability is mainly attributed to the presence of flavonoids and hydroxycinnamic acids in the epidermal tissue. In two field cabinet experiments with two different clones of Norway spruce we assessed the seasonal accumulation of UV-B screening pigments under near-ambient, and close-to-zero UV-B irradiation. At the beginning of needle development, i.e. in June, kaempferol 3- O -glucoside was the dominant UV-B screening pigment. It was replaced during needle differentiation by the more effective diacylated flavonol glucosides, particulary kaempferol 3- O -(3",6"- O -di- p -coumaroyl)-glucoside, which reached highest concentrations in July. In addition to the soluble pool of diacylated flavonol glucoside derivatives, a cell wall-bound UV-B screen in the epidermal cell walls was formed during needle differentiation, consisting mainly of p -coumaric acid and kaempferol 3- O -glucoside. An effect of UV-B radiation on the accumulation of diacylated flavonol glucosides was only observed in 1996 with clone 2, when the concentrations of kaempferol 3- O -(3",6"- O -di- p -coumaroyl)-glucoside were significantly higher in July and August under field, and near-ambient than under close-to-zero UV-B irradiance. For wall-bound p -coumaric acid and kaempferol 3- O -glucoside UV-B radiation enhanced the concentrations of these compounds by approximately 20% in relation to the concentrations in close-to-zero UV-B-treated plants in both field cabinet experiments.     

Senescence and hyperspectral reflectance of cotton leaves exposed to ultraviolet-B radiation and carbon dioxide

The objectives of this study were to determine the effects of UV-B radiation and atmospheric carbon dioxide concentrations ([CO(2)]) on leaf senescence of cotton by measuring leaf photosynthesis and chlorophyll content and to identify changes in leaf hyperspectral reflectance occurring due to senescence and UV-B radiation. Plants were grown in controlled-environment growth chambers at two [CO(2)] (360 and 720 micro mol mol(-1)) and three levels of UV-B radiation (0, 7.7 and 15.1 kJ m(-2) day(-1)). Photosynthesis, chlorophyll, carotenoids and phenolic compounds along with leaf hyperspectral reflectance were measured on three leaves aged 12, 21 and 30 days in each of the treatments. No interaction was detected between [CO(2)] and UV-B for any of the measured parameters. Significant interactions were observed between UV-B and leaf age for photosynthesis and stomatal conductance. Elevated [CO(2)] enhanced leaf photosynthesis by 32%. On exposure to 0, 7.7 and 15.1 kJ of UV-B, the photosynthetic rates of 30-day-old leaves compared with 12-day-old leaves were reduced by 52, 76 and 86%, respectively. Chlorophyll pigments were not affected by leaf age at UV-B radiation of 0 and 7.7 kJ, but UV-B of 15.1 kJ reduced the chlorophylls by 20, 60 and 80% in 12, 21 and 30-day-old leaves, respectively. The hyperspectral reflectance between 726 and 1142 nm showed interaction for UV-B radiation and leaf age. In cotton, leaf photosynthesis can be used as an indicator of leaf senescence, as it is more sensitive than photosynthetic pigments on exposure to UV-B radiation. This study revealed that, cotton leaves senesced early on exposure to UV-B radiation as indicated by leaf photosynthesis, and leaf hyperspectral reflectance can be used to detect changes caused by UV-B and leaf ageing.