981 resultados para math.GR


Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文新种部分,记述了分布在横断山地区、台湾以及苏门答腊、菲律宾等地果蝇科的新种55种,异物同名3种。在果蝇属果蝇亚属的伊米果蝇种组建立了一个新的种复组-弯头果蝇种亚组(Drosophila curviceps species subgroup);在quadrilineata种亚组内建立了一个新的种复组-背条果蝇种复组(Drosophila notostriata species-complex)。对横断山地区的果蝇进行研究,计有119个种,主要由东洋种、古北种、特有种和广布种组成;对其渊源关系进行分析。运用分支分类学的观点和方法对伊米果蝇种组中5个种亚组间的系统发育进行研究显示,hypocausta种亚组最原始,位地分支图的最底部,是外群向伊米果蝇种组过渡的一个类群,进化中心在热带的苏门答腊及其附近;其次分化的immigrans种亚组其进化中心仍在热带的苏门答腊及其附近;但该亚组的特种逐渐向北扩散,在中国云南的西双版纳及其附近地区形成次级进化中心。伊米果蝇种组总的进化方向是从热带向温带的逐渐演化。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

报道了用MBE生长轻掺Si高迁移率GaAs材料的杂质补偿特性实验研究。已得到77K温度下迁移率为16.2×10~4cm~2/(V·s)的GaAs材料。样品的Hall测量结果表明:在较低的杂质浓度范围(1×10~(13)cm~(-3)<n<1×10~(15)cm~(-3))内,在大体相同的生长温度(590℃左右)下,选择适当的生长速率Gr会增强对浅受主杂质的抑制作用,同时也会一致Si的自补偿效应,减小杂质的补偿度N_a/N_d之值,从而提高MBE外延GaAs材料的迁移率。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this work, The TBS glass microspheres doped with Er3+ for morphology-dependent resonances of upconversion emission were designed. The glass sample components are 25TiO(2)-27BaCO(3)-8Ba(NO3)(2)-6ZnO(2)-9CaCO(3)-5H(3)BO(3)-10SiO(2)-7water glass-3Er(2)O(3) (wt%), and the emission spectra of TBS glass and a TBS glass microsphere (about 48 mum in diameter) were measured under 633 nm excitation and discussed. The strong morphology-dependent resonances of upconversion luminescences in the microsphere were observed. The observed resonances could be assigned by using the well-known Lorenz-Mie Formalism. (C) 2003 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文以开顶箱法分别控制CO2、O3浓度,在CO2、O3浓度升高及其二者相互作用条件下,分析沈阳城市森林主要树种油松、银杏活性氧水平,抗氧化系统活性以及膜脂过氧化程度动态变化,揭示城市油松、银杏抗氧化系统对全球气候变化的响应规律。 1. 在短期(60天)内CO2浓度倍增(700µmol mol-1)使油松、银杏超氧自由基(O2-.) 产生速率与过氧化氢(H2O2)含量减少,而抗坏血酸(ASA)含量与超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDAR)、脱氢抗坏血酸还原酶(GR)活性升高,丙二醛(MDA)含量下降。与对照相比,大多数测定显示出显著差别。植株抗氧化能力增强,对活性氧清除能力提高。但长期(70天以上)CO2浓度倍增处理则使试验结果发生逆转。 2. 高浓度O3(80nmol mol-1)使O2-. 产生速率提高,H2O2 含量增加,MDA含量也随之增加。ASA含量与SOD、APX及GR活性在高浓度臭氧熏蒸的前期升高,但随着臭氧暴露时间的延长ASA含量与保护酶活性均变得低于对照。因此,在高浓度臭氧熏蒸的前期(30天以内),抗氧化酶能够在一定程度上调节自身的活性适应环境变化。但连续的高浓度臭氧胁迫导致活性氧含量升高,抗氧化酶活性下降。在试验后期, 虽然肉眼可见的伤害尚未观察到,但丙二醛含量显著升高,膜脂过氧化程度加深,油松、银杏的抗氧化系统已经不能抵抗长期臭氧胁迫所带来的氧化伤害。 3. 高浓度O3熏蒸初期,经倍增浓度CO2预处理的油松、银杏O2-.产生速率与H2O2含量,SOD、APX、MDAR、GR活性与自然O3浓度条件下植株无显著差异,表明高浓度CO2预处理银杏、油松对O3的抵抗能力增强。但随着高O3曝露时间的延长,O2-.产生速率与H2O2含量增加,SOD、APX、MDAR与GR活性低于对照,而且(经高CO2预处理后移入自然CO2、O3浓度中的植株)之差异逐渐增大,在试验末期达到差异显著水平,表明高CO2诱导油松、银杏产生的对O3胁迫的高抗性是不稳定的。 4.高浓度O3预处理(50天)使油松、银杏的抗氧化系统活性下降,已如前述。将经高浓度O3预处理的油松、银杏分别置入倍增浓度CO2与自然CO2环境中,随后的20天高CO2处理使活性氧水平低于自然CO2环境,而抗氧化酶活性高于自然CO2环境。这表明倍增CO2浓度能有效的恢复高浓度O3处理对油松、银杏的氧化胁迫。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在人类活动导致全球变暖的前提下,由于全球气温的升高,地表水分加速向空中蒸发。从20世纪70年代至今,地球上严重干旱地区的面积几乎扩大了一倍。这一增长的一半可归因于气温升高而不是降雨量下降,因为实际上同期全球平均降水量还略有增长。干旱对陆地植物和农林生态系统产生深远影响,并已成为全球变化研究的一个重要方面。位于青藏高原东部的川西亚高山针叶林是研究气候变暖对陆地生态系统影响的重要森林类型。森林采伐迹地、人工林下和林窗环境作为目前该区人工造林和森林更新的重要生境,其截然不同的光环境对亚高山针叶林更新和森林动态有非常重要的影响。凋落物产生的化感物质可通过影响种子萌发和早期幼苗的定居而影响种群的建立和更新,而人工林和自然林物种以及更新速度的差异性也都受凋落物的影响。 云杉是川西亚高山针叶林群落的重要树种之一,在维持亚高山森林的景观格局和区域生态安全方面具有十分重要的作用,其自然更新能力及其影响机制一直是研究的热点问题。本试验以云杉种子和2年生幼苗为研究对象,从萌发、根尖形态、幼苗生长、光合作用、渗透调节和抗氧化能力等方面研究了不同光环境下水分亏缺和凋落物水浸液对云杉种子和幼苗生长的影响。旨在从更新的角度探讨亚高山针叶林自然更新的过程,其研究成果可在一定程度上为川西亚高山针叶林更新提供科学依据,同时也可为林业生产管理提供科学指导。主要研究结论如下: 水分亏缺在生长形态、光合作用、抗氧化能力、活性氧化对云杉幼苗都有显著影响。总体表现为,水分亏缺导致了云杉幼苗的高度、地径、单株总生物量降低,增加了地下部分的生长;水分亏缺显著降低了云杉叶片中相对含水量、光合色素、叶氮含量,净光合速率和最大量子产量(Fv/Fm),提高了幼苗叶片中膜脂过氧化产物(MDA)的含量;水分亏缺提高了幼苗叶片中过氧化氢(H2O2)含量,超氧荫离子(O2-)生成速率以及脯氨酸和抗氧化系统的活性(ASA, SOD, CAT, POD, APX和GR)。从这些结果可知,植物在遭受水分亏缺导致的伤害时,其自身会形成防御策略,并通过改变形态和生理方面的特性以减轻害。但是,这种自我保护机制依然不能抵抗严重水分亏缺对植物的伤害。 模拟林下低光照条件显著增加单株植物的地上部分生长,尤其是其叶片的比叶面积(叶面积/叶干重),同时其光合色素含量和叶片相对含水量也显著增加,这些改变直接导致植株光合速率和生物量的增加。同时,与高光照水平相比,低光照幼苗的膜脂过氧化产物(MDA)和活性氧物质均较低,显示出低光照比高光照水平对植物的更低的氧化伤害。尽管低光照也导致大部分抗氧化酶活性降低,但这正显示出植物遭受低的氧化伤害,更印证了前面的结论。 凋落物水浸液影响了云杉种子的萌发和根系的生长,更在形态、光合作用、抗氧化能力、活性氧物质以及叶氮水平上显著影响了云杉幼苗,其中,以人工纯林凋落物的影响更有强烈。具体表现在,种子萌发速率和萌发种子幼根的长度表现为对照>自然林处理>人工纯林;凋落物水浸液抑制种子分生区和伸长区的生长,人工林处理更降低了根毛区的生长,使根吸水分和养分困难。对2年生幼苗的影响主要表现在叶绿素含量、光合速率以及叶氮含量的降低;膜脂过氧化产物、活性氧物质和抗氧化酶系统的显著增加。同样的,人工纯林处理对云杉幼苗的影响显著于自然林处理。 在自然生态系统中,由于全球变暖气温升高导致的水分亏缺和森林凋落物都存在森林的砍伐迹地,林窗和林下环境中。我们的研究表明,与迹地或林窗强光照比较,林下的低光照环境由于为植物的生长营造了较为湿润的微环境,因此水分亏缺在林下对云杉幼苗造成的影响微弱。这可以从植物的形态、光合速率以及生物量积累,过氧化伤害和抗氧化酶系统表现出来。另一方面,凋落物水浸液在模拟林下低光照环境对植物的伤害也微弱于强光照环境,这与强光照环境高的水分散失导致环境水分亏缺有关;而人工纯林处理对云杉幼苗的伤害比对照和自然林处理显示出强烈的抑制作用。 Under the pre-condition of global warming resulted from intensive human activities, water in the earth’s surface rapidly evaporates due to the increase of global air temperature. From 1970s up to now, the area of serious drought in the world is almost twice as ever. This increase might be due to the increasing air temperature and not decreasing rainfall because global average rainfall in the corresponding period slightly is incremental. Drought will have profound impacts on terrestrial and agriculture-forest system and has also become the important issue of global change research. The subalpine coniferous forests in the eastern Qinghai-Tibet Plateau provide a natural laboratory for the studying the effects of global warming on terrestrial ecosystems. The light environment significantly differs among cutting blanks, forest gap and understory, which is particularly important for plant regeneration and forest dynamics in the subalpine coniferous forests. Picea asperata is one of the keystone species of subalpine coniferouis forests in western China, and it is very important in preserving landscape structure and regional ecological security of subalpine forests. The natural regeneration capacities and influence mechanism of Picea asperata are always the hot topics. In the present study, the short-term effects of two light levels (100% of full sunlight and 15% of full sunlight), two watering regimes (100% of field capacity and 30% of field capacity), two litter aqueous extracts (primitive forest and plantation aqueous extracts) on the seed germination, early growth and physiological traits of Picea asperata were determined in the laboratory and natural greenhouse. The present study was undertaken so as to give a better understanding of the regeneration progress affected by water deficit, low light and litter aqueous extracts. Our results could provide insights into the effects of climate warming on community composition and regeneration behavior for the subalpine coniferous forest ecosystem processes, and provide scientific direction for the forest production and management. Water deficit had significant effects on growth, morphological, physiological and biochemical traits of Picea asperata seedlings. Water deficit resulted in the decrease in height, basal diameter, total biomass and increase in under-ground development; water deficit significantly reduced the needle relative water content, photosynthetic pigments, needle nitrogen concentration, net photosynthetic rate and the maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA) in Picea asperata seedlings; water deficit also increased the rate of superoxide radical (O2-) production, hydrogen peroxide (H2O2) content, free proline content and the activities of antioxidant systems (ASA, SOD, POD, CAT, APX and GR) in Picea asperata seedlings. These results indicated that some protective mechanism was formed when plants suffered from drought stress, but the protection could not counteract the harm resulting from the serious drought stress on them. Low light in the understory significantly increased seedling above-ground development, especially the species leaf area (SLA), and photosynthetic pigments and relative needle content. These changes resulted in the increase in net photosynthetic rate and total biomass. Moreover, the lower MDA content and active oxygen species (AOS) (H2O2 and O2-) in low light seedlings suggested that low light had weaker oxidative damage as compared to high light. Lower antioxidant enzymes activities in low light seedlings indicated the weaker oxidative damage on Picea asperata seedlings than high light seedlings, which was correlative with the changes in MDA and AOS. Litter aqueous extracts affected seed germination and root system of Picea asperata seedlings. Significant changes in growth, photosynthesis, antioxidant activities, active oxygen species and leaf nitrogen concentration were also found in Picea asperata seedlings, and plantation treatment showed the stronger effects on these traits than those in control and primitive forest treatment. The present results indicated that seed germination and radicle length parameters in control were superior to those in primitive forest treatment, and those of primitive forest treatment were superior to plantation treatment; litter aqueous extracts inhibited the meristematic and elongation zone, and plantation treatment caused a decrease in root hairs so as to be difficult in absorbing water and nutrient in root system. On the other hand, litter aqueous extracts significantly decreased chlorophyll content, net photosynthetic rate and leaf nitrogen concentration of Picea asperata seedlings; MDA, AOS and antioxidant system activities were significantly increased in Picea asperata seedlings. Similarly, plantation treatment had more significant effect on Picea asperata seedlings as compared to primitive forest treatment. In the nature ecosystem, water deficit resulted from elevating air temperature and litter aqueous extract may probably coexist in the cutting blank, forest gap and understory. Our present study showed that water deficit had weaker effects on low light seedlings in the understory as compared to high light seedlings in the cutting blank and forest gap. The fact was confirmed from seedlings growth, gas exchange and biomass accumulation, peroxidation and antioxidant systems. This might be due to that low light-reduced leaf and air temperatures, vapour-pressure deficit, and the oxidative stresses can aggravate the impact of drought under higher light. On the other hand, litter aqueous extracts in the low light had weaker effects on the Picea asperata seedlings than those at high light level, which might be correlative to the water evapotranspiration under high light. Moreover, plantation litter aqueous extracts showed stronger inhibition for seed germination and seedling growth than control and primitive forest treatments.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

大气臭氧的损耗导致了地球表面具有生物学效应的紫外线-B(UV-B)辐射增强。同时,大气成分变化中除了UV-B辐射增强外,氮沉降是一个新近出现而又令人担忧的环境问题,其来源和分布正在迅速扩展到全球范围,并不断向陆地和水生生态系统沉降。本试验在四川省境内的中国科学院茂县生态站内进行,以云山、冷杉、色木槭和红椋子幼苗为模式植物,从生长形态、光合作用、抗氧化能力和矿质营养等方面研究了青藏高原东缘4种树苗对全球变化-增强UV-B辐射和氮供应(氮沉降)的响应。该试验为室外盆栽试验,包括四个处理:(1)大气UV-B辐射+无额外的氮供应(C);(2)大气UV-B辐射+额外的氮供应(N);(3)增强UV-B辐射+无额外的氮供应(UV-B);(4)增强UV-B辐射+额外的氮供应(UV-B+N)。其目的:一方面有助于丰富我国对全球变化及区域响应研究的全面认识,进一步完善在全球气候变化条件下臭氧层削减和氮沉降对陆地生态系统影响的内容;另一方面,在一定程度上有助于我们更好的理解在全球变化下森林更新的早期过程。具体结果如下: 增强的UV-B辐射在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有显著的影响。UV-B辐射增强对幼苗的影响不仅与物种有关,而且,还与氮营养水平相关。总体表现为,高的UV-B辐射导致了色木槭和红椋子幼苗叶片的皱缩和卷曲,并降低了色木槭幼苗的叶片数和叶重,在额外的氮供应下,云杉、冷杉和红椋子的叶重也显著地降低了;色木槭和红椋子幼苗叶片的解剖结构受到了增强的UV-B辐射的影响,增强的UV-B辐射显著地降低了色木槭叶片的栅栏组织厚度,提高了红椋子叶片的厚度;增强的UV-B辐射显著地降低了4种幼苗的单株总生物量、植物地下部分的生长、总叶绿素含量 [Chl (a + b)]、净光合速率和最大量子产量(Fv/Fm),提高了4种幼苗叶片的膜脂过氧化(MDA含量),改变了植物体不同器官中的矿质元素含量;增强的UV-B辐射提高了冷杉、色木槭和红椋子叶片中的过氧化氢含量(H2O2)、超氧负离子(O2-)生成速率,在额外的氮供应下,云杉叶片中的活性氧含量也显著地提高了;在无额外的氮供应条件下,增强的UV-B辐射显著地提高了4种幼苗叶片中的UV-B吸收物质、脯氨酸含量和抗氧化酶的活性(SOD、POD、CAT、GR和APX)。在额外的氮供应条件下,UV-B辐射的增强却显著地降低了冷杉叶片中脯氨酸含量和红椋子叶片中UV-B吸收物质含量,但是,在4种幼苗叶片中,5种抗氧化酶的活性对UV-B辐射的增强没有明显的规律性,增强的UV-B辐射显著地提高了云杉叶片中的POD、SOD和GR的活性,提高了冷杉叶片中的POD和GR活性,提高了色木槭叶片中的POD、SOD和CAT活性和红椋子幼苗叶片中的POD和SOD活性。从这些结果可知,植物在遭受高的UV-B辐射导致的过氧化胁迫时,植物体内形成了一定的保护机制,但是,这种保护不能抵抗高的UV-B辐射对植物的伤害。 额外的氮供应在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有一定的影响,不同幼苗对额外的氮供应响应不同,并且受到UV-B辐射水平的影响。在当地现有的UV-B辐射水平下,额外的氮供应显著地提高了幼苗的单株总生物量、植物地下部分的生长、Chl (a + b)、净光合速率(红椋子除外)、UV-B吸收物质(冷杉除外)、脯氨酸含量(红椋子除外)和部分抗氧化酶的活性,降低了H2O2的含量、O2-的生成速率和MDA含量(红椋子除外),改变了植物体内部分矿质元素含量,显著地提高了云杉和冷杉叶片中的Fv/Fm。这些指标总体表明,在当地现有大气UV-B辐射水平下,额外的氮供应对植物的生长和发育是有利的。在增强的UV-B辐射水平下,4种幼苗的生长形态和光合大部分指标都没有受到额外氮供应的影响,额外的氮供应提高了红椋子幼苗的单株总生物量和Chl (a + b)含量,提高了冷杉和色木槭叶片中的活性氧含量和MDA含量,却降低了红椋子叶片中的活性氧含量;额外的氮供应也提高了云杉、色木槭和红椋子叶片中UV-B吸收物质和脯氨酸含量,降低了冷杉叶片中UV-B吸收物质和脯氨酸含量;在抗氧化酶活性方面,额外的氮供应降低了云杉、冷杉叶片中5种抗氧化酶的活性和红椋子叶片中POD和GR的活性,提高了色木槭叶片中的POD和SOD的活性;4种幼苗植物体内的矿质元素含量对额外的氮供应没有显著的规律性。从这些结果可知,在高的UV-B辐射下,额外的氮供应提高了云杉、冷杉和色木槭幼苗对高的UV-B辐射的敏感性,然而,额外的氮供应却促进了红椋子幼苗的生长,原因可能是,在高的UV-B辐射下,额外的氮供应增加了红椋子叶片的厚度、叶重和叶片数,降低了叶片中活性氧含量的结果。表明在高的UV-B辐射水平下,额外的氮供应降低了红椋子幼苗对高的UV-B辐射的敏感性。 在全球变化的趋势下,UV-B辐射增强和氮沉降可能同时存在,我们的研究表明,与大气UV-B辐射+无额外的氮供应处理相比,增强UV-B辐射+额外的氮供应处理显著地降低了幼苗的单株总生物量(红椋子除外)、Chl (a + b)、净光合速率、Fv/Fm(冷杉除外)和MDA含量(红椋子除外),提高了活性氧含量 (云杉除外)、UV-B紫外吸收物质含量(冷杉除外)、脯氨酸含量和部分抗氧化酶的活性,改变了植物体不同器官中的矿质元素含量。结果表明,在当地现有条件下,全球变化(UV-B辐射增强和氮沉降)对云杉、冷杉和色木槭幼苗的生长是不利,尽管植物体内一些抗氧化性指标提高了,然而,却对红椋子幼苗的单株总生物量的累积没有显著的影响。 The depletion of the ozone led to the increase of ultraviolet-B (UV-B) with biological effects in the earth’s surface. At the same time, except for enhanced UV-B radiation, nitrogen deposition was an anxious environmental problem at present, rapidly expanding to the global scope and continuously depositing to land and aquatic ecosystem. The experiment was conducted in Maoxian Ecological Station of Chinese Academy of Sciences, Sichuan province, China. Picea asperata, Abies faxoniana, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings were selected as model plants to assess the effects of enhanced UV-B radiation and supplemental nitrogen supply on growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings in east Qinghai-Tibetan Plateau. The experiment was potted outdoor, including 4 treatments: (1) ambient UV-B without supplemental nitrogen (control, C); (2) ambient UV-B with supplemental nitrogen (N); (3) enhanced UV-B without supplemental nitrogen (UV-B); (4) enhanced UV-B with supplemental nitrogen (UV-B+N). One hand, it was helpful for enriching our country to comprehensive understanding of the researches in the global change and the region response, further perfecting the effects of the depleted ozone layer and nitrogen deposition on land ecosystem under the global change; the other hand, it was favorable for us to better understanding of the early process of forest renews under the global change. The results were as follows: Enhanced UV-B radiation had significant effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings. The effects of enhanced UV-B on plants were not only related with species, but also related with nitrogen nutrient level. Generally, the increase of UV-B radiation led to the shrinkage and curl of leaves in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, and reduced the number of leaf and leaf weight of Acer mono Maxim seedlings, under supplemental nitrogen supply, leaf weight of Picea asperata, Abies faxoniana and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings significantly also reduced; the anatomical features of leaf in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings affected by enhanced UV-B radiation, the increase of UV-B radiation markedly reduced the palisade tissue thickness of Acer mono Maxim leaf and enhanced the leaf thickness of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings; the enhanced UV-B radiation significantly reduced total biomass per plant of 4 species seedlings, the growth of the underground parts, Chl (a + b), net photosynthetic rate and maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA content) and changed the content of mineral elements in different parts of plants; the enhanced UV-B radiation also increased the rate of superoxide radical (O2-) production and hydrogen peroxide (H2O2) content in leaves of Abies faxoniana, Acer mono Maxim, Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, under supplemental nitrogen supply, the reactive oxygen species in leaves of Picea asperata seedlings also significantly increased by enhanced UV-B radiation; under without supplemental nitrogen supply, enhanced UV-B radiation evidently induced an increase in UV-B absorbing compounds, proline content and the activities of antioxidant enzymes (SOD, POD, CAT, GR and APX) of leaves in 4 species seedlings. Under supplemental nitrogen supply, enhanced UV-B radiation induced a decrease in proline content of leaves in Abies faxoniana seedlings and UV-B absorbing compounds of leaves in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, but, there were no obvious rules in the activities of five antioxidant enzymes of 4 species seedling leaves to enhanced UV-B radiation, enhanced UV-B radiation significantly increased the activities of POD, SOD and GR in Picea asperata leaves, the activities of POD and GR in Abies faxoniana leaves and the activities of POD, SOD and CAT in Acer mono Maxim leaves. The results indicated that some protective mechanism was formed when plants were exposed to enhanced UV-B radiation, but the protection could not counteract the harm of high UV-B radiation on plants. Supplemental nitrogen supply had some effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits. The response of 4 species seedlings was different to supplemental nitrogen supply, and was affected by UV-B levels. Under local ambient UV-B radiation, supplemental nitrogen supply significantly increased the total biomass per plant, the growth of underground parts, Chl (a + b), net photosynthetic rate (except for Acer mono Maxim seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and the activities of some antioxidant enzymes, and reduced H2O2 content, the rate of O2- production and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and changed the content of mineral elemental in different parts; supplemental nitrogen supply also evidently increased Fv/Fm in Picea asperata and Abies faxoniana seedlings. These results indicated that supplemental nitrogen supply was favorable for the growth of plants under local ambient UV-B radiation. Under enhanced UV-B radiation, mostly parameters in growth and morphology of 4 species seedlings were not affected by supplemental nitrogen supply. Supplemental nitrogen supply increased the total biomass per plant and Chl (a + b) of Swida hemsleyi (Schneid. et Wanger.) Sojak seedling, increased the reactive oxygen species and MDA content in Abies faxoniana and Acer mono Maxim leaves, and reduced the reactive oxygen species in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves; supplemental nitrogen supply also increased UV-B absorbing compounds and proline content in Picea asperata, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, decreased UV-B absorbing compounds and proline content in Abies faxoniana leaves; in the activities of antioxidant enzymes, supplemental nitrogen supply significantly reduced the activities of antioxidant enzymes in Picea asperata and Abies faxoniana leaves and the activities of POD and GR in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, and increased the activities of POD and SOD in Acer mono Maxim leaves; the content of mineral elements in 4 species seedlings was no significantly rule to supplemental nitrogen supply. We knew from the results, under enhanced UV-B radiation, supplemental nitrogen supply made Picea asperata, Acer faxoniana and Acer mono Maxim seedlings more sensitivity to enhanced UV-B radiation, however, accelerated the growth of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings. The reason was probably that supplemental nitrogen supply increased the leaf thickness, leaf weight and leaf number, reduced the reactive oxygen content of leaf in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings grown under high UV-B radiation. This showed that supplemental nitrogen supply reduced the sensitivity of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings to high UV-B radiation. Under the tendency of the global change, enhanced UV-B radiation and nitrogen deposition may probably coexist. The results showed, compared with the treatment of ambient UV-B radiation without supplemental nitrogen supply, the treatment of enhanced UV-B radiation with supplemental nitrogen supply significantly reduced the total biomass per plants (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), Chl (a + b), net photosynthetic rate, Fv/Fm and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), and increased reactive oxygen content (except for Picea asperata seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content and part antioxidant enzymes, and changed the content of mineral elements of different parts. The results indicated that the global change (enhanced UV-B and nitrogen deposition) were not favorable for the growth of plants under local ambient UV-B radiation and nitrogen nutrient level,, though increased some antioxidant indexes, however, the treatment of enhanced UV-B with supplement nitrogen supply did not significantly affect on the biomass accumulation of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

大气CO2浓度的增加已经成为不可争议的事实。预计本世纪末大气CO2浓度将增加到约700µmol mol-1。森林年光合产量约占陆地生态系统年光合产量的70%。森林树木是一个巨大的生物碳库,约占全球陆地生物碳库的85%。森林树木对CO2的固定潜力是缓解由大气CO2浓度升高引起的未来全球气候变化问题的决定性因子之一。红桦(Betula albosinensis Burk.)是川西亚高山采伐迹地自然或人工恢复的重要树种。本研究以1a红桦幼苗为模式植物,采用人工模拟的方法,研究CO2浓度升高对不同种内竞争强度(种群水平)下红桦幼苗的生理特征、生长、干物质积累及其分配的影响,探讨在种内竞争生长条件下红桦幼苗的“光合适应机理”与生长特征,为西南亚高山森林生产力对未来全球变化的预测提供重要参考。 本研究的主要结果如下: 1)在种内竞争生长条件下红桦幼苗经过CO2浓度升高熏蒸4个月后,叶片出现“光合适应”现象。与对照相比,低种植密度(28株m-2)和高种植密度(84株m-2)条件下的红桦幼苗净光合速率(A)、气孔导度(gs)、蒸腾速率(E)、表观量子产量(AQY)和羧化速率(CE)显著降低,而水分利用效率(WUE)则显著提高。CO2浓度升高处理的红桦幼苗叶片Rubisco活性、单位叶面积N浓度、叶绿素a、叶绿素b和类胡萝卜素浓度都显著降低。但CO2浓度对红桦幼苗的叶绿素a与叶绿素b的比值没有显著影响。CO2浓度升高显著增加红桦幼苗单位叶面积的非结构性碳水化合物(TNC)浓度,结果是红桦幼苗的比叶面积(SLA,cm2 g-1)显著降低。 2)与对照相比,CO2浓度升高处理的红桦幼苗高、基径、单叶面积和侧枝的相对生长速率(R GR)显著提高,尤其在试验处理的早期。CO2浓度升高既增加单株红桦幼苗总叶片数量又增加单叶面积,结果是单株红桦幼苗的总叶面积比对照显著增加。 3)CO2浓度升高处理显著增加红桦幼苗干物质积累(尤其是细根生物量),改变了红桦幼苗生物量的分配格局。与对照相比,CO2浓度升高处理的红桦幼苗叶重比(LWR)、叶面积比(LAR)、叶根重比(Wl/Wr)和源汇重比(leaf weight to non-leaf weight ratio, Wsource/Wsink)显著下降(高种植密度的LWR除外),而根冠比(R/S)则显著增加。在两种种植密度条件下,CO2浓度升高显著增加红桦幼苗根生物量的分配比率,显著降低叶片的生物量分配比率,对主茎、侧枝以及地上生物量的分配比率不变或约有下降。 总之,长期生长在CO2浓度升高条件下的红桦幼苗光合能力下降,并伴随Rubisco活性、叶N浓度、光合色素浓度的显著降低以及TNC浓度的显著增加。支持树木光合速率下降与Rubisco活性、叶N浓度下降以及TNC浓度增加紧密相关的假设。CO2浓度升高处理红桦幼苗的早期相对生长速率大大高于对照,而后期迅速下降,说明红桦幼苗生物量的显著增加主要归功于CO2浓度升高的早期促进作用和叶面积的显著增加。CO2浓度升高显著增加红桦幼苗根系生物量和根冠比,表明红桦幼苗“额外”固定的C向根系转移。 The steady increae of atmospheric CO2 concentration([CO2])has been inevitable fact. Models predict that the atmospheric [CO2] will increase to about 700µmol mol-1 at the end of the twenty-first century. As trees constitute a majoor carbon reservoir–85% of total plant carbon is found in forest, and their ability to sequester carbon is a key determinant of future global change problems caused by increases in atmospheric CO2. In addition to the role of forests in the global carbon cycle, inceased growth could be of economic benefit, for example, offsetting deleterious effects of climatic changes. Betula albosinensis (Burk.) usually emerges as the pioneer species in initial stage and as constructive species in later stages of forest community succession of mountain forest area, and also is one of important tree species for afforestation in logged area, in southwesten China. In this experinment, Betula albosinensis seedling (one-year-old) was used as the model plant. B. albosinensis seedlings were grown under two all-day [CO2], ambient (about 350 µmol·mol-1) and elevated [CO2] (about 700 µmol·mol-1), and two planting densities of 28 plants per m2 and 84 plants per m2. The objectives were to characterize birch mature leaf photosynthesis, growth, mass accumulation and allocation responses to long-tern elevated growth [CO2] under the influences of neighbouring plants, and to assess whether elevated [CO2] regulated birch mature leaf photosynthetic capacity, in terms of leaf nitrogen concentration (leaf [N]), activity of ribulose bisphosphate carboxygenase (Rubisco), Rubisco photosynthetic efficiency, and total nonstructural carbohydrates (TNC) concentration, and also to provide a strong reference to predict the productivity of subalpine forests under the future global changes. The results are as follows: 1) B.albosinensis seedlings exposed to elevated [CO2] for 120 days, photosynthetic acclimation phenomena occurred. At two planting densities, leaves of birch seedlings grown under elevated [CO2] had lower net photosynthetic rate (A), stomatal conductance (gs), transpiration (E), apparent quantum yield (AQY) and carboxylated efficiency (CE) and higher water use efficiency (WUE), compared to those of B.albosinensis seedlings grown under ambient [CO2]. Based on the leaf area, leaf [N], Rubisco activity and photosynthetic pigments concentrations of B. albosinensis seedlings grown under elevated [CO2] were significantly lower than those grown under ambient [CO2]. The ratio of chlorophyll a to chlorophyll b concentration was not affected by elevated [CO2]. Under elevated [CO2], the TNC concentration per unit leaf area significantly increased, resulting in significant decrease in specific leaf area. Thus leaf photosynthetic capacity of B. albosinensis seedlings would perform worse under rising atmospheric [CO2] and the influences of neighbouring plants. 2) Under elevated [CO2], the relative growth rate (RGR) of B. albosinensis seedlings height, basal diameter, a leaf area and branch length significantly increased, especially at the initial stage of exposure to elevated [CO2], and a leaf area and leaf numbers per B. albosinensis seedling also significantly increased. Thus the total leaf area per B. albosinensis seedling was significantly increased under elevated [CO2]. 3) As the increase of RGR and total leaf area, biomass of B. albosinensis seedling grown elevated [CO2] was higher, compared to that of B.albosinensis seedlings grown at ambient [CO2]. Elevated [CO2] changed the biomass allocation pattern of B. albosinensis seedling. At two planting densities, B. albosinensis seedlings grown elevated [CO2] had lower leaf weight to total weight ratio (LWR), leaf area to total weight ratio (LAR) and leaf weight to non-leaf weight ratio (Wsource/Wsink), but higher root weight to shoot weight ratio (R/S), compared to those of B.albosinensis seedlings grown at ambient [CO2]. Under elevated [CO2], roots biomass to total biomass ratio was signigicantly increased, leaves biomass to total biomass ratio was significantly decreased. The main stem and branch biomass to total biomass ratio were not affected by elevated [CO2]. In conclusion, our results supported the hypothesis that the decline in photosynthetic capacity of C3 plants will appear after long-term exposure to elevated [CO2], accompanying with the significant decrease in Rubisco activity, leaf N concentration, photosynthetic pigments concentration, and significant increase in total non-structural carbohydrates concentration. Our results also have shown that the increase of biomass of B. albosinensis seedlings should be attributed to initial stimulation on RGR and total leaf area resulted from elevated [CO2]. Under elevated [CO2], the extra carbon sequestered by B.albosinensis seedlings transferred into under-ground part because of increase in root biomass and R/S.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

近二十多年来,基于对臭氧层衰减、紫外线B(UV-B)增强的担心,研究者希望了解到紫外线辐射对不同作物的影响情况,增强UV-B辐射条件下是否对作物的生长发育、产量质量构成威胁。在本试验中,我们首先探讨了双子叶作物黄瓜(Cucumis sativus)和大豆(Glycine max)对不同紫外波段的生物效应[分别为B-UVA(315-400 nm),N-UVA(315-340 nm),B-UVB(275-400 nm)和N-UVB(290-340 nm),UV-(>400nm)作对照]。我们观察到所有的UV波段处理都使黄瓜和大豆的生长受到抑制,并且细胞受到不同程度的氧化伤害;UV波段处理的作用效果与不同波段的紫外有效生物辐射剂量有关。处理差异在UV-B波段内部和UV-A波段内部同样存在。植物生长UV辐射公式(BSWF)能很好的预测本试验UV-B波段内的平均植物效应,但不能预测UV-A波段的植物效应。短波UV-A的生物作用强于长波UV-A。光合色素的变化与UV波谱差异和种间差异有关。在高的紫外/可见光背景下,UV-A处理同UV-B同样导致光合色素的降低,但黄瓜类胡萝卜素/叶绿素比例升高。与其他研究者的试验结果比较后,我们认为紫外线B辐射的生物效应一致性很高,但紫外线A波段的生物学效应存在较大争议。因此我们在本试验的基础上仅进行荞麦[苦荞(Fagopyrum tataricum Gaertn.)和甜荞(Fagopyrum esculentum Moench.)]对紫外线B波段的响应研究。 我们对苦荞品种-圆籽荞进行了连续两个生长季节的大田半控制试验以观察UV-B辐射对苦荞生长、发育、产量及叶片色素的影响;试验小区进行降低UV-B、近充足UV-B和增强UV-B辐射处理。我们的试验表明在不同强度UV-B辐射下苦荞的生长、地上部生物量积累及最终产量都有所下降,但苦荞的发育加快;当前条件下的日光紫外线B辐射对植物生长和产量也造成负面影响。植物光合色素被日光及增强UV-B辐射降低;UV化合物及卢丁含量在中低剂量的UV-B辐射强度下显著升高,但在高剂量的增强UV-B辐射下短期升高后迅速下降。我们的试验表明苦荞是一个对UV-B高度敏感的作物。苦荞对UV-B的敏感性与UV-B剂量、外界环境因素及生长季节有关。 单个苦荞品种的试验结果使我们认识到外界UV-B辐射已经对苦荞生长发育构成逆境条件,未来全球气候变化条件下增强紫外线B辐射可能使其处于更不利的生长环境中。因此我们有进行了多个种群进行UV-B响应观察并筛选耐性种群。我们对15个苦荞种群进行增强UV-B辐射处理(6.30 kJ m2 UV-BBE,模拟当地25%的臭氧衰减),我们观察苦荞UV-B辐射效应存在显著的种内差异,UV-B辐射对多数种群具有抑制作用,但对一些种群还有刺激作用。我们采用主成分分析方法与作物UV-B响应指数(RI)来评价苦荞作物UV-B辐射耐性。我们发现作物的UV-B耐性不仅与其原产地背景UV-B强度有关,而且与作物相对生长效率、次生代谢产物含量(如卢丁)及其他因素有关。我们观察到苦荞伸展叶总叶绿素变化与UV-B耐性成正相关;室内苦荞幼苗的UV-B辐射致死试验表明:苦荞种群死亡率与其UV-B耐性成负相关。 此外,我们对甜荞的UV-B辐射响应也进行了初步研究。选取美姑甜荞、巧家甜荞和云龙甜荞进行5个梯度的增强UV-B辐射室外模拟试验。我们观察到UV-B辐射显著降低了甜荞的生长、生物量及产量;并严重影响了甜荞的生殖生长,降低了花序数、种子数和结实率;并且UV-B辐射对甜荞的抑制作用存在显著的剂量效应。三种甜荞品种存在显著的种内差异,其中美姑品种UV-B耐性最强,且膜脂受UV-B辐射氧化伤害最小,这与该品种UV-B辐射下较高的GR酶活性、APX酶活性和PPO酶活性、以及含量更高的抗坏血酸有关。甜荞的次生代谢也受到增强UV-B辐射的影响,其香豆酰类化合物在UV-B辐射下升高显著,而槲皮素含量也在高剂量UV-B辐射下有所增加;卢丁含量依赖UV-B辐射剂量而变化,中低剂量UV-B辐射下其卢丁含量逐渐升高,但在高剂量辐射下逐渐下降。 通过对生长在高海拔地区的荞麦作物(苦荞和甜荞)进行的室外研究,我们认识到作物不同品种存在很大的耐性差异,这就为UV-B耐性育种创造了有利条件。进一步加大荞麦种质资源筛选力度并深入认识荞麦抗性机理,在此基础上通过杂交或其他基因融合手段培育抗性品种,对高剂量UV-B辐射地区的荞麦产量的提高将起到重要推动作用,并使荞麦生产能有效应对未来全球气候变化条件下UV-B辐射可能升高的威胁。 During last few decades, due to concern of ozone layer depletion and enhancement of ultraviolet B radiation(UV-B, 280-315 nm), the agronomist want to know the responses of different crop species to UV-B. In the first experiment of our study, the effect of different UV band [B-UVA(315-400 nm), N-UVA(315-340 nm), B-UVB(275-400 nm), N-UVB(290-340 nm)and UV-(>400nm, as control)] on the cucumber(Cucumis sativus)and soybean(Glycine max)were investigated in growth room. Spectra-dependent differences in growth and oxidation indices existed within UV-A bands as well as UV-B bands. The general biological effects of different band were UV- < B-UVA< N-UVA<N-UVB<B-UVB. The plant growth biologically spectra weighting function(BSWF)matched well with average plant response in UV-B region, but not in UV-A region. Shorter UV-A wavelength imposed more negative impact than longer UV-A wavelength did in both species. The effect on photosynthetic pigment was related to different UV bands and different species. The photosynthetic pigment content was decreased by UV-A spectra as well as UV-B spectra. In comparison with the results of previous studies, we found that the wavelength-dependent biological effect of ultraviolet B radiation has high consistency, but the biological effect of ultraviolet-A radiation was inconsistent. We narrow our following study on the effect of ultraviolet B radiation on the buckwheat(tartary buckwheat and common buckwheat). The tartary buckwheat(Fagopyrum tataricum Gaertn.)cultivars Yuanziqiao was grown in the sheltered field plots for two consecutive seasons under reduced, near-ambient and two supplemental levels of UV-B radiation. The crop growth, photosynthetic pigments, total biomass, final seed yield and thousand-grain weight were decreased by near-ambient and enhanced UV-B radiation, while crop development was promoted by enhanced UV-B radiation. Leaf rutin concentration and UV-B absorbing compound was generally increased by UV-B with the exception of 8.50 kJ m-2 day-1 supplemental levels. Our results showed that tartary buckwheat is a potentially UV-B sensitive species. Study on one cultivars showed that ambient solar radiation had present a stress to tartary buckwheat. This makes it necessary to observe the UV-B response of many cultivars and screen tolerant cultivars. Fifteen populations of tartary buckwheat were experienced enhanced UV-B radiation simulating 25% depletion of the stratospheric ozone layer in Kunming region, and plant responses in growth, morphology and productivity were observed. Principal components analysis(PCA)was used to evaluate overall sensitivity of plant response to UV-B as well as response index. The different populations exhibited significant differences in responses to UV-B. The photosynthetic pigments of young seedlings were also affected significantly under field condition. On the other hand, the healthy seedlings of different populations were exposed to the high level of UV-B radiation in growth chambers to determine the plant lethality rate. The plant tolerance evaluated by multivariate analysis was positively related to total plant chlorophyll change, but negatively related to lethality rate. In other hand, the UV-B responses of the other important cultivated buckwheat species, common buckwheat(Fagopyrum esculentum Moench.), were also studied preliminarily. Three widespread cultivated variety(Meigu, Qiaojia and Yunlong cultivars)were provided with five level of enhanced UV-B radiation outdoors. We observed that the crop growth, development and production were significantly decreased, and reproductive production, like anthotaxy number, seed number and seed setting ratio, was also decreased. Dose-dependent inhibition effect caused by enhanced UV-B radiation also existed in common buckwheat. Significant intraspecific difference existed in those three cultivars. The Meigu cultivars with dwarfed growth and lower production have highest UV-B tolerance as well as lowest damage in cell membrane, this could be associated with profound enhancements of glutathione reductase(GR)activity, ascorbate peroxidase activity and polyphenol oxidase activity as well as higher ascorbic acid concentration. The secondary metabolism was also affected by UV-B radiation, with profound elevation of coumarin compound and moderate increase of quercetin concentration. Rutin concentration was peaked in 5kJ m-2 UV-B. The contrasting effect of UV-B radiation on different populations indicated that there existed abundant genetic resources for selecting tolerant populations of common and tartary buckwheat. Much effort needed be pose on screening of buckwheat germplasm and clarification of mechanism of buckwheat tolerance to UV-B. On this base the tolerant cultivars could be bred by hybridization and other gene transfusion method, this would help increase buckwheat yield in high ambient UV-B region and counteract the effect of possible enhanced UV-B radiation in future.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

土壤是人类赖以生存的自然环境和农业生产的重要资源,世界面临的粮食、资源和环境问题与土壤密切相关,目前危害土壤的主要因素是干旱和重金属污染。杨树具有适应性强、生长快和丰产等特性,本论文以青杨组杨树为模式植物,采用植物生态、生理及生物化学等方法,研究杨树对土壤干旱和锰胁迫的生态生理反应以及种群间差异,研究成果可为我国干旱半干旱地区营造人工林、防止沙漠化提供理论依据,也为恢复与重建重金属污染地区退化生态系统提供科学指导。主要研究结果如下: 1. 青海杨不同种群对干旱胁迫的响应差异 干旱胁迫显著降低了两个青海杨种群(干旱种群和湿润种群)生物量积累,包括株高、基径、干物质积累等,通过植物结构的调整,有更多的生物量向根部分配。干旱胁迫还显著降低了叶绿素和类胡萝卜素含量,增加了游离脯氨酸和总氨基酸含量。另一方面,干旱胁迫诱导了活性氧的积累,作为第二信使,激活了抗氧化系统,包括抗坏血酸(ASA)含量和酶系统如超氧化物歧化酶(SOD),愈创木酚过氧化物酶(GPX),抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)。这样,杨树既有避旱机制又有耐旱机制,使其在干旱胁迫下有相当程度的可塑性。与湿润种群相比,干旱种群杨树有更多的生物量分配到根部,积累了更多的游离脯氨酸和总氨基酸来进行渗透调节,并且有更有效的抗氧化系统,包括更高含量的ASA 和更高活性的APX 和GR,这些使得干旱种群杨树比湿润种群杨树对干旱有更好的耐性。 2. 喷施硝普钠(SNP)对青海杨阿坝种群干旱胁迫耐性的影响 干旱胁迫显著的降低了青海杨阿坝种群的生长和生物量积累以及叶片相对含水量,还诱导了脯氨酸的合成以进行渗透调节。干旱胁迫下过氧化氢(H2O2)显著累积从而造成对膜脂和蛋白的伤害,使得丙二醛和蛋白羰基含量升高。干旱胁迫下喷施SNP可以减轻干旱胁迫造成的伤害,包括增加叶片的相对含水量,增加脯氨酸和总氨基酸的积累,并激活抗氧化酶系统如SOD,GPX和APX,从而减少丙二醛(MDA)和蛋白羰基(C=O)的积累,但是在水分良好情况下SNP的效果不显著。 3. 青杨不同种群对锰胁迫的生长与形态响应差异 在同一锰浓度下,干旱种群的耐性指数都要高于湿润种群,这表明青杨对干旱和高锰胁迫具有交叉耐性。两个种群的株高,生物量和叶绿素含量都随锰浓度的升高而逐渐下降。就累积浓度而言,0 和0.1 mM 锰胁迫下,干旱种群积累的锰浓度要高于湿润种群,而在高浓度锰胁迫下(0.5 和1 mM),湿润种群要高于干旱种群。在0,0.1 和0.5 mM下,锰大多积累在根中,叶片次之,茎中最少。而在1 mM,锰更多的积累在叶片中。就累积总量而言,在各个锰浓度胁迫下,根,茎和叶相比,两个种群青杨都是叶片累积的锰总量要高于根和茎。两个种群间比较,对照中没有显著区别,0.1 mM 锰胁迫下,湿润种群根中累积的锰要高于干旱种群,而在地上部中,干旱种群要高于湿润种群。而0.5 和1 mM 锰胁迫下,根、叶、茎+叶、根+茎+叶中,锰累积总量都是湿润种群高于干旱种群。锰胁迫下,青杨叶片数和叶面积包括总叶面积和平均叶面积都显著降低。叶片横切面的光学显微观察结果表明未经锰胁迫的栅栏组织的细胞饱满,海绵组织发达、清晰;胁迫后杨树叶片栅栏组织细胞出现不同程度的皱缩,海绵组织几乎不可见,此外还发现输导组织在胁迫下密度变小和分生组织严重割裂等现象。 4. 青杨不同种群对锰胁迫的生理与生化响应差异 青杨两个种群脱落酸(ABA)含量在锰胁迫下都显著增加,干旱种群的增幅更大。三种多胺含量在锰胁迫下显示了不同的响应趋势:腐胺在两个种群的各个锰处理下都增加,亚精胺只在干旱种群中显著增加,而精胺除了干旱种群在1 mM 下有所增加外,在锰胁迫下变化很小。谷胱甘肽含量随锰浓度升高而增加,在0.5 mM 锰时达到最高值,1mM 时有所下降。植物络合素(PCs)含量与非蛋白巯基(NP-SH)趋势相似,随锰浓度的升高而增加,且干旱种群中含量要高于湿润种群。锰处理还引起氧化胁迫,表现为过氧化氢和丙二醛含量增加。SOD 活性在湿润种群中,在0 到0.5 mM 锰胁迫下活性升高,但在1 mM 锰胁迫时,其活性有所下降。而在干旱种群中,SOD 活性变化较小,并始终维持在一个较高的水平。APX 活性在两个种群中都随锰浓度的升高而增加,干旱种群活性要高于湿润种群。锰胁迫还显著增加了酚类物质的含量,同时GPX 和多酚氧化酶(PPO)活性也随锰浓度的升高而增加。干旱种群的酚类含量和GPX 与PPO 活性都要高于湿润种群。锰胁迫还改变了氨基酸的含量和构成,根据锰胁迫下浓度变化的不同,可以将游离氨基酸分为三组:第一组包括,谷氨酸,丙氨酸和天门冬氨酸,这一组氨基酸含量在锰胁迫下有所下降。第二组包括缬氨酸,亮氨酸和苏氨酸含量在锰胁迫下基本不变化或变化很小。剩下的氨基酸为第三组,这组氨基酸含量在锰胁迫下显著增加,而根据增加的幅度又可以将它们分为两个亚组,丝氨酸,酪氨酸,苯丙氨酸,组氨酸和脯氨酸,在1 mM 下的含量是对照的4 倍以上。异亮氨酸,赖氨酸,精氨酸和甘氨酸含量在1 mM 下是对照含量的2 倍以下。同时,同一锰浓度下,干旱种群比湿润种群积累的氨基酸含量要高。 Soil is the indispensable environment for human survival and important resource foragriculture development. Food and environmental problems facing the world are all closelyrelated to soil and nowadays it is threatened by many factors, among which drought stress andheavy metal pollution are the most serious ones. Poplars (Populus spp.) are importantcomponents of ecosystem and suitable as a source of fuel, fiber and lumber due to their fastgrowth. In this study, different populations of Section Tacamahaca spach were used as modelplants to investigate the adaptability to drought stress and manganese toxicity and differencesbetween populations from dry and wet climate regions. Our results can provide theoreticalevidence for the afforestation and prevention of desertification in the arid and semi-arid areas,and also can supply scientific direction for the reconstruction and rehalibitation of ecosystemscontaminated by heavy metals. The results are as follows: 1. Differences in ecophysiological responses to drought stress in two contrastingpopulations of Populus przewalskii Drought stress not only significantly affected dry mass accumulation and allocation, butalso significantly decreased chlorophyll pigment contents and accumulated free proline andtotal amino acids. On the other hand, drought also significantly increased the levels ofabscisic acid and reactive oxygen species, as secondary messengers, to induce the entire set ofantioxidative systems including the increase of reduced ascorbic acid content and the activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and glutathioneredutase. Thus the combination of drought avoidance and tolerance mechanisms conferredpoplar a high degree of plasticity in response to drought stress. Compared with the wetclimate population, the dry climate population showed lower dry matter accumulation andallocated more biomass to root systems, and accumulated more free proline and total aminoacids for osmotic adjustment. The dry climate population also showed more efficientantioxidant systems with higher content of ascorbic acid and higher activities of ascorbateperoxidase and glutathione redutase than the wet climate population. All these made the dryclimate population superior in adaptation to drought stress than the wet climate population. 2. Effect of exogenous applied SNP on drought tolerance in Populus przewalskii Drought stress significantly increased hydrogen peroxide content and caused oxidativestress to lipids and proteins assessed by the increase in malondialdehyde and total carbonylcontents, respectively. The cuttings of P. przewalskii accumulated proline and other aminoacids for osmotic adjustment to lower water potential, and activated the antioxidant enzymes such as superoxide dismutase, guaiacol peroxidase and ascorbate peroxidase to maintain thebalance of generation and quenching of reactive oxygen species. Moreover, exogenous SNPapplication significantly heightened the growth performance of P. przewalskii cuttings underdrought treatment by promotion of proline accumulation and activation of antioxidant enzymeactivities, while under well-watered treatment the effect of SNP application was very little. 3. Morphological responses to manganese toxicity in the two contrasting populations ofPopulus cathayana High concentration of manganese caused significant decrease in shoot height andbiomass accumulation. The tolerance index of the dry climate population was significantlyhigher than that of the wet climate population, suggesting the superior Mn tolerance in theformer and the existence of cross-tolerance of drought stress and high Mn toxicity. Injuries tothe leaf anatomical features were also found as the reduced thickness in palisade and spongyparenchyma, the decreased density in the conducting tissue and the collapse and split in themeristematic tissue in the central vein. As for the Mn concentrations in the plant tissues, under0, 0.1 and 0.5 mM, most of the Mn accumulated in the roots, then leaves, and stem the least, while under 1 mM, most of the Mn accumulated in the leaves. As far as the total amounts ofMn extraction are concerned, the leaf extracted more Mn than the root and stem in the twopopulations under various Mn concentrations. There is no difference between the twopopulations under control. Under 0.1 mM, the wet climate population extracted higher Mn inthe root than the dry climate population, while in the shoot, the dry climate populationextracted much more Mn. Under 0.5 and 1 mM, the wet climate population translocated moreMn both in the root and the shoot than the dry climate population. 4. Physiological and biochemical responses to manganese toxicity in the two contrastingpopulations of Populus cathayana Mn treatment resulted in oxidative stress indicated by the oxidation to lipids, proteinsand DNA. A regulated network of defence strategies was employed for the chelation,detoxification and tolerance of Mn including the enhanced synthesis of ABA and polyamines,the accumulation of free amino acids, especially His and Pro, and the activation of theenzymes superoxide dismutase and guaiacol peroxidase. Contents of non-protein thiol,reduced glutathione, phytochelatins and phenolics compounds and activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase also increased significantly forantioxidant or chelation functions. The wet climate population not only accumulated lessabscisic acid, free amino acids, phytochelatins and phenolics compounds, but also exhibitedlower activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase thusresulting in more serious oxidative damage and more curtained growth.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

杨树具有分布广、适应性强,在生态环境治理和解决木材短缺方面均占有重要位置。青杨(Populus cathayana Rehd.)是青杨派树种的重要成员之一,也是我国的特有种。本研究通过对不同水分梯度的干旱胁迫下青杨形态和生理生化的反应,不同pH值盐碱胁迫下不同海拔和不同气候地区的四个青杨种群在生理生态上的反应差异,以及在干旱和低温胁迫下青杨lea2, lea3组基因表达差异的研究,从形态、生理、生化和分子生物学水平系统地研究了青杨在不同逆境胁迫下的反应和青杨不同种群在盐碱胁迫下的反应差异。主要研究结果如下: 1. 青杨在干旱胁迫下的反应机制:中度和重度干旱胁迫下植株的生长受到明显抑制。表现在光合系统上青杨的净光合同化速率(A)下降,主要原因是气孔导度(gs),胞间二氧化碳浓度(Ci)下降。另外最大量子产量(Fv/Fm)、光化学猝灭效率(qP)降低反应了干旱胁迫下光合系统II(PSII)受到严重损伤, 而且非光化学猝灭效率(qN)上升,导致可利用化学能产量下降,叶绿体产生淀粉的量减少。qP降低qN上升导致产生的过量电子对光合系统的伤害造成活性氧以及丙二醛(MDA)的含量增加。超微解剖结构显示,干旱胁迫增强时,叶绿体内淀粉粒的数目减少,而且叶绿体、线粒体等细胞器中嗜锇颗粒的数目增加。为清除细胞内的活性氧,植物一般的反应是抗氧化系统酶活性增加,对青杨来讲超氧化物歧化酶(SOD), 抗坏血酸过氧化物酶(APx)活性的增加远大于过氧化物酶(POD),这显示了在青杨中SOD、APx酶在清除活性氧的作用上大于POD。另外同工酶研究结果显示这些酶活性的升高主要是由于各条同工酶带表达量的增加,而不是诱导新酶带的产生。另外,75% FC水分处理下有些指标非但没有下降,像A和有效光量子产量(Y)的值都略有增加,而且gs同时增加。另外,100% FC比75% FC细胞内淀粉粒的数目少一些,但有少量的嗜锇颗粒。这证明100% FC土壤水分也许并非最适合青杨生长。 2. 盐碱胁迫对不同海拔地区青杨种群的反应差异:青杨高海拔和低海拔种群的各种生理特性随着pH值上升都受到了很大的影响。两种群叶和根中Na+、K+ 含量, Na+/K+比率随着pH值的上升影响显著。在pH值高于10.4时高海拔种群叶和根中Na+/K+比率急剧下降但是低海拔种群中却一直维持在较高水平。两种群中MDA、脯氨酸(Proline)的含量,抗氧化系统酶的活性都受到了严重的影响,证明两个种群都属于盐碱胁迫敏感类型但是高海拔的种群对盐碱胁迫的耐性要高于低海拔。这主要是由于高海拔种群一般具有耐干旱、低温胁迫的能力,而植物的抗逆机制一般都有共通之处。 3. 盐碱胁迫对不同气候地区青杨种群的反应差异:盐碱胁迫下两种群的光合作用受到明显的抑制,具体表现在叶绿素的含量和A 显著下降。净光合速率的下降主要是由于叶片gs,Ci 值降低引起的。与湿润地区的种群相比盐碱胁迫增强时,干旱地区的种群叶绿素含量和光合能力的升高与K+离子含量增加有关。植物维持细胞质高K+/Na+值对植物的抗盐性有很重要的作用。为清除盐碱胁迫产生的活性氧,抗氧化系统酶活性增加。盐碱胁迫下干旱地区的种群在SOD、CAT 和谷胱甘肽还原酶(GR)等酶的活性均显著上升,而湿润地区种群只有谷胱甘肽氧化酶(GST)的活性明显增加,说明干旱种群的抗氧化酶系统在较高盐碱胁迫下的保护作用要强于湿润种群。这主要是由于植物抗盐碱胁迫与抗干旱胁迫在一些方面的机制是一致的,抗旱种群一般也能抵抗一定程度的盐碱胁迫。 4. 青杨lea2、lea3 基因在干旱和低温胁迫下的表达差异:通过荧光定量PCR 分析,lea2、lea3 组基因在干旱和低温胁迫下在mRNA 水平的瞬时表达量明显升高,说明了两基因在青杨耐干旱和低温胁迫上都起显著的作用。而且两基因在干旱胁迫下,表达量的升高和降低的时间近乎同步,表明两基因在干旱胁迫下对植物应急保护机制的启动都发挥着重要的作用。低温胁迫下lea3 基因在mRNA 水平上表达量显著上升的时间要早于lea2,而且lea3 基因的持续作用时间明显长于lea2 组基因,说明了低温胁迫开始时lea3基因在植物应对逆境的作用上要大于lea2 基因。 Poplars play an important role in lumber supply, and are important components of ecosystems due to their wide distribution and well adaptation. Populus cathayana Rehd., which belongs to Populus Sect. Tacamahaca Spach, is one of the most important resources of poplars and is specialist to china. In this study, different altitudes and climates populations of P. cathayana were used as experiment materials to investigate the adaptability to drought and salt-alkali stresses. And the cultures of P. cathayana were used to analyze the lea2 and 3 group genes expression when exposed to drought and low temperature stresses. The results are as follows: 1. A large set of parallel responses to drought stress: Drought stress caused pronounced growth inhibition. A decreased significantly and was mainly the result of gs and Ci down. Besides, Fv/Fm, qP decreased and that reflected the harmful effects to PSII of drought stress. In accordance with qN increasing, decreased useful energy production caused the starch numbers reduction in chloroplast. The qP up and qN down improved the levels of ROS and MDA. Starch numbers in chloroplast reduced and plastoglobuli numbers increased when soil water content decreased. To reduce ROS, the activities of SOD, APX, CAT and PPO were activated. The isozymes results show that the rising activities of the antioxidant enzymes resulted from certain isoform content increased, and not from the new band produced. Interestingly, morphological results show 100%FC maybe wasn’t the favorite water content for P. cathayana growth. 2. Effect of salt-alkali stress on morphological and physiological changes in two different altitudes populations of P. cathayana: We compared the physiological responses of two populations of Populus cathayana Rehder, originating from altitudes 2,840 m and 1,450 m. Our results demonstated that Na+ and K+ contents, and Na+/K+ ratios in leaves and roots are greatly affected by pH values. At pH 10.4, the Na+/K+ ratios in both leaves and roots sharply dropped in the higher altitude population but were always maintained at higher levels in the lower altitude population. The pH values causing maximum malondialdehyde (MDA) level, free proline content and antioxidant enzyme activities were significantly different in two populations. These results indicated that the higher altitude population exhibits greater tolerance to alkalinity stress than does the lower altitude population. 3. Morphological and physiological changes in two different climates populations of P. cathayana when exposed to salt-alkali stress. Salt-alkali stress caused pronounced inhibition of the growth and especially in photosystem. Pigments content and A decreased significantly and at the same time gs and Ci decreased too. Compared with wet climate population, the Chlorophyll content and A increased in drought climate population as pH value rising was related to the K+ content increasing. It is important to resist salt-alkali stress that the K+/Na+ ratio matained at high level in cytoplasm. To reduce ROS content, the SOD, CAT and GR activities rised significantly in drought population but only GST increased in wet population. The drought population showed higher salt-alkali tolerance than the wet population mainly resulted from the fact that drought tolerance was in accordance with salt-alkali tolerance to some extent. 4. The different expressional model of lea2 and lea3 gene when P. cathayana was exposed to drought and cold stress. RT-PCR results show both lea2 and lea3 suddenly expressed significantly in mRNA level under drought and cold stress. The expression level of two genes reached optimal level at the same time. But under cold stress, the earlier significantly rising expressional time and the longer maintained higher level time in lea3 than lea2 elucidated that lea3 may be more important than lea2 in resisting cold stress in short time in P. cathayana.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

毛壳菌属很多种类具有重要生防价值,其生防机理包括对植物病原真菌的重寄生作用、诱导植物产生抗病性、产生抗真菌活性的次生代谢产物等。迄今,学界对毛壳菌的研究主要集中在毛壳菌的生防机理,毛壳菌活性次生代谢产物的分离等方面。本研究致力于产抗生素的毛壳菌的种间原生质体融合,从产抗生素毛壳菌菌株的筛选开始,进而对产抗生素的角毛壳菌进行诱变选育,最终用产不同抗生素的角毛壳菌与球毛壳菌进行种间原生质体融合。主要有以下五方面研究结果。 1、毛壳菌抗真菌活性物质产生菌株的筛选:不同毛壳菌菌株发酵液采用琼脂扩散法对植物病原真菌进行抑菌活性试验,结果显示,菌株CH08和CH23的发酵液对芒果炭疽、苹果炭疽和马铃薯晚疫菌具有抑制作用。菌株CH16和CH17的发酵液对芒果炭疽菌、苹果炭疽菌有抑制作用。菌株CH21发酵液对辣椒炭疽菌和西瓜枯萎菌有抑制作用。经形态学研究,菌株CH08、CH16、CH17和CH23鉴定为球毛壳菌,菌株CH21鉴定为角毛壳菌。对角毛壳菌与球毛壳菌菌株发酵液抑菌谱比较,发现角毛壳菌与球毛壳菌发酵液具有明显不同的抑菌谱,表明角毛壳菌与球毛壳菌产生不同的抗真菌活性物质。 2、角毛壳菌(CH21)和球毛壳菌(CH08)原生质体制备和再生条件研究:考察了菌龄、酶浓度、稳渗剂及其浓度、酶解温度、酶解时间及再生培养基对原生质体制备和再生的影响。用菌龄为生长54 h的角毛壳菌菌丝,以0.06 M磷酸缓冲液(pH6.0)配制成含蜗牛酶15 mg/ml、溶壁酶10 mg/ml、蔗糖0.6 mol/L的酶解液,30℃酶解1.5 h,原生质体释放量2.02×107个/g;以PDA为再生培养基,0.7 mol/L的蔗糖再生稳渗剂,再生率可达51.45%。用菌龄为生长48 h的球毛壳菌菌丝,以0.06 M磷酸缓冲液(pH6.0)配制成含蜗牛酶15 mg/ml、溶壁酶10 mg/ml、蔗糖0.6 mol/L的酶解液,30℃酶解1 h,原生质体释放量达1.57×108个/g;以PDA为再生培养基,0.7 mol/L的蔗糖为再生稳渗剂,再生率可达41.48%。 3、角毛壳菌(CH21)原生质体紫外诱变选育:以CH21为出发菌株,制备原生质体进行紫外诱变,诱变条件为:15 w紫外灯,距离30 cm,照射90 s,致死率80%~85%。建立了诱变菌株初筛的双层平板筛选模型。经平板初筛和摇瓶复筛,获得一株突变菌株CH21-I-402,其发酵液抑菌活性较出发菌株提高18.3%。 4、抗性标记菌株的获得:菌株CH21-I-402和CH08抗生素药敏试验表明, CH21-I-402菌株对潮霉素有抗性、对G418(Geneticin)敏感,菌株CH08对潮霉素和G418都敏感。根癌农杆菌EHA105介导的新霉素磷酸转移酶基因转化球毛壳菌,经PCR检测,新霉素磷酸转移酶基因成功转化进菌株CH08-GR70,CH08-GR120。转化子对G418抗性提高3~4倍,对潮霉素仍然比较敏感。 5、以G418和潮霉素抗性为筛选标记的原生质体融合与融合菌株AFLP分析:制备角毛壳菌CH21-I-402和球毛壳菌CH08-GR70原生质体,以35%的PEG6000为助融剂进行原生质体融合,以65 μg/ml的潮霉素和60 μg/ml G418为抗性筛选标记,获得46个再生菌株。再生菌株连续传代5代后,再生菌株表现出多种形态类型。利用AFLP技术对再生菌株及亲本菌株基因组DNA分析表明,再生菌株PF1、PF26为融合菌株。抑菌活性测试表明,融合菌株PF26发酵液对芒果炭疽菌和苹果轮纹菌有强的抑制作用,且抑菌活性比亲本球毛壳菌明显提高。 Chaetomium spp. have great potentials as biocontrol agents against a range of plant pathogens on the basis of its mycoparasitism, induced plant disease resistance, production of antifungal metabolites, and so on. Previous researches on C. spp. mostly focused on the mechanisms of its biocontrol and the isolation of secondary metabolites. In this study, screening antifungal C. spp., mutation breeding of C. cupreum and interspecies protoplast fusion between C. cupreum and C. globosum were carried out, respectively. The corresponding results are as follows: Firstly, among more than 40 C. spp., the strains produced anti-fungal antibiotics were screened by agar diffusion experiments. Results showed that both CH08 and CH23 had inhibition against Colletotrichum gloeosporioides, Cladosporium fulvum, and Phytophthora infestans. Both CH16 and CH17 had inhibition against Colletotrichum gloeosporioides and Cladosporium fulvum. In addition, CH21 exhibited anti-fungal activity against Fusarium oxysporum f. sp niveum and Colletotrichum capsici. Furthermore, CH08, CH16, CH17 and CH23 were identified as C. globosum, CH21 was proved to be C. cupreum based on morphology. The comparison of the anti-fungal spectrum between C. cupreum and C. globosum, showed they could produce different antibiotics. Secondly, specified protocols for preparing and regenerating protoplasts from mycelia of C. cupreum CH21 and C. globosum CH08 were studied. The effects of the age mycelia, the concentration of enzyme, digestion temperature and time, kinds of osmotic stabilizer and regeneration medium on protoplasts preparation and regeneration were all optimized, respectively. In one protocol, with 15 mg/mL snailase, 10 mg/mL lywallzyme, 0.6 M sucrose, in 0.06 M phosphate buffer (pH6.0), and digested for 1.5 h at 30 ºC, 2.02×107 protoplasts from each gram mycelia were obtained from cultures of C. cupreum CH21 grown in potato dextrose broth (PDB) medium for 54 h. And when 0.7 M sucrose was used as osmotic stabilizer in the regeneration medium OPDA (potato dextrose agar with osmotic stabilize), the regeneration efficiency of protoplasts was 51.45%. In another protocol, with 15 mg/mL snailase, 10 mg/mL lywallzyme, 0.6 M sucrose, in 0.06 M phosphate buffer (pH6.0), and digested for 1 h at 30 ºC, 1.57×108 protoplasts from each gram mycelia were obtained from cultures of C. globosum CH08 grown in PDB for 48 h. And when 0.7 M sucrose was used as osmotic stabilizer in the regeneration medium OPDA, the regeneration efficiency of protoplasts was 41.48%. Thirdly, the mutagenesis conditions and secondary screening model of C. cupreum CH21 were explored. An 80% to 85% death rate could be achieved when the protoplasts of C. cupreum CH21 were irradiated by 15 w UV lamp from 30 cm distance for 90 s. In addition, the doublelayer plate’s method for the primary screening of high-producing antibiotics strains was established. A high yielding antibiotic mutant CH21-I-402 was obtained through the primary screening on plate and the secondary selection in Erlenmeyer flask, compared to the original CH21 strain, the antifungal activity of the mutant CH21-I-402 was increased by 18.3%. Fourth, the sensitivity to antibiotics of both C. cupreum CH21-I-402 and C. globusm CH08 was detected. Results showed C. cupreum CH21-I-402 was sensitive to G418 (Geneticin) (Gs) and resistant to Hygromycin B(Hr), and C. globusm CH08 was sensitive to both G418 (Geneticin) (Gs) and Hygromycin B(Hs). At the same time, neomycin phosphotransferase II (npt II) gene was transformed into C. globusm CH08(Gs, Hs) mediated by Agrobacterium tumefaciens EHA105, and the npt II gene was verified by polymerase chain reaction in resistance to G418 strains CH08-GR70 and CH08-GR120. The transformants still showed sensitive to Hygromycin B(Hs). Finally, a selection system for hybrids was set up by interspecies protoplast fusion between C. cupreum and C. globusm using dominant selective drug resistance markers. At first, protoplasts of C. cupreum CH21-I-402 (Hr, Gs) and C. globusm CH08-GR70 (Hs, Gr) were prepared, then the protoplasts were fused in the presence of 35% polyethylene glycol 6000 and regenerated on OPDA medium with 65 μg/ml Hygromycin B and 60μg/ml G418, at last 46 colonies with Hr and Gr were obtained. Even after 5 generations’ subculture, most of the colonies displayed significant difference in taxonomic characteristics with their parental strains. Regenerated strains PF1 and PF26 were confirmed as fusants by amplified fragment length polymorphisms analysis with the genomic DNA as the model. PF26 showed higher inhibitory activity against Colletotrichum gloeosporioides and Macrophoma kuwatsukai than that of the parental strain C. globusm.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Deconfinement phase transition and neutrino trapping in (proto)neutron star matter are investigated in a chiral hadronic model (also referred to as the FST model) for the hadronic phase (HP) and in the color-flavor-locked (CFL) quark model for the deconfined quark phase. We include a perturbative QCD correction parameter alpha(s) in the CFL quark matter equation of states. It is shown that the CFL quark core with K-0 condensation forms in neutron star matter with the large value of alpha(s). If the small value of alpha(s) is taken, hyperons suppress the CFL quark phase and the HP is dominant in the high-density region of (proto)neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter alpha(s) or decreasing the bag constant B and the strange quark mass m(s) can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of (proto)neutron stars are not sensitive to the QCD correction parameter alpha(s).