模拟沉积环境下的温度、湿度对叶片DNA降解的影响

为了探讨自然环境下生物体内DNA的降解,残存规律,设计了模拟特殊自然沉积环境的实验装置以控制温度、湿度和含氧水平,采用Brassica chinensis叶片作为实验材料,从实验装置中定期采集叶片组织进行总DNA的提取与检测,然后采用定量PCR方法,对目标DNA片段(28S rDNA,630bp)进行特异扩增,依据PCR反应的强弱,描绘目标DNA的变化曲线。共报道了8种不同模拟条件下的DNA降解(残存)趋势。实验结果如下：1)环境温度升高,DNA的降解速率增加,如温度从10℃上升到30℃,DNA的降解速率最大可增加近300倍。环境含水量增加可明显促进DNA的降解,在本实验中潮湿状态(浸没在水中)与干燥状态的叶片相比。其DNA的残存量在相同的实验时间内可相差近700倍。初步的实验结果表明,环境温度和湿度均是影响DNA降解的重要因素。     

温度和水分状况对几种不同类型植物叶片水势和延伸生长的影响

在田间条件下研究了温度、相对湿度、土壤水分对玉米、高粱、茄子、豇豆、河北杨和泡桐六种植物LER2)和ψWL3)日变化的影响。结果表明,ψWL日变化呈正弦曲线,即早晨、晚上高,中午低;土壤水分亏缺,中午大气ψWV4)愈低,ψWL降低愈多。在土壤供水良好的条件下,玉米、高粱、河北杨、泡桐叶片生长与温度密切相关,因此白天生长快,晚上生长慢;若中午ψWV太低,生长减慢,使叶片生长呈双峰曲线,即午前及18:00左右生长快。若土壤水分亏缺,白天ψWV太低,白天生长慢,晚上生长快。茄子和豇豆叶片生长对水分亏缺更敏感,晚上生长快,白天生长慢,干旱处理叶片在白天中午有收缩现象。     

植物叶片和角果的碳酸酐酶与光合速率的关系研究

以3种植物为材料,对其叶片、角果的碳酸酐酶活性日变化和相应的净光合速率日变化以及不同叶位的叶片和不同长度角果的CA活性和净光合速率关系进行研究.结果表明,在日变化中,油菜和诸葛菜的CA活性与其净光合速率之间存在显著性正相关,羽衣甘蓝则不明显.但3种植物不同叶位的叶片和不同长度角果的CA活性与净光合速率之间都呈显著正相关,说明无论是植物的营养器官叶片,还是生殖器官角果,CA活性的高低对净光合速率都有较大的影响.     

树木叶片稳定碳同位素分馏对环境梯度的响应

除了自身的遗传因素外,植物对稳定碳同位素的分馏还受温度、水分状况、光照等多种环境因素的影响。通过对生长在中国北热带、亚热带和温带的13个气候区树木的稳定碳同位素分馏与环境要素的关系的研究得出,不同气候条件下树木叶片稳定碳同位素比率(δ13C)和稳定碳同位素分辨率(Δ)差异明显,分别在-23.759‰--33.914‰和14.581‰-24.354‰的范围内。且由南向北,δ13C值呈现逐渐加重的趋势、而Δ值逐渐减小。年均温度、相对湿度、降雨量及无霜期等与δ13C值呈显著负相关、与Δ值显著正相关;年均日照时数、气温年较差、蒸发量、纬度及海拔等与δ13C值呈显著正相关、而与Δ值显著负相关;而经度、年极端最高气温等与δ13C和Δ值的相关性较弱。δ13C和Δ值的变化幅度和趋势在年均温度、年较差、无霜期、活动积温分别达到约19℃、23℃、309d、6000℃出现转折,这些指标在此基础上继续增加反而使叶片δ13C值增大、Δ值减小。而当年均降雨量和相对湿度分别超过1105mm、75%以及蒸发量小于约1700mm后,δ13C和Δ值随之变化的幅度也变小。结果表明在亚热带和温带的分界线以南,水热条件均能满足植物正常生理活动的需要,环境条件的相对改变对植物生理活动及叶片稳定碳同位素分馏的影响较小;而在北方,干旱、低温等极端的外界环境条件加剧了对植物生长和生理指标的影响、造成了不同环境梯度下叶片稳定碳同位素分馏的差异。     

干旱区叶片形态特征与植物响应和适应的关系

叶片形态是指示植物适应特定环境的重要指标。由于植物叶片形态不仅对时空环境变化具有极强的敏感性和可塑性, 而且能够通过叶片形态的调整调节自身的生存适应能力, 所以叶片形态学研究一直是植物生理及植物生态学研究中的热点。该文在总结前人叶片形态学研究成果的基础上, 探索建立了简单的叶片形态指标分类体系; 结合物质能量交换的物理学原理, 回顾总结了叶片表观形态变化与叶片物质能量交换之间的相关关系; 应用叶片形态影响物质能量交换的物理学原理, 重点分析了干旱区植物叶片表观形态对低水分环境、高辐射(或高温)的响应与适应特征; 最后, 在回顾分析的基础上, 对叶片形态研究中存在的几个问题进行了讨论。     

植物叶片最大羧化速率与叶氮含量关系的变异性

叶片最大羧化速率是表征植物光合能力的关键参数, 受到光照、温度、水分、CO₂浓度、叶片氮含量等多个要素的控制。准确地模拟植物叶片最大羧化速率对环境因子的响应是预测未来植被生产力和碳循环过程的前提。目前大多数陆地碳循环过程模型以Farqhuar光合作用模型为基础模拟植物的光合作用, 关于植物叶片的最大羧化速率与叶氮含量关系的模拟方法却各不相同。该文汇总了1990-2013年国内外植物叶片光合速率观测研究文献中叶片最大羧化速率与叶氮含量的关系式及相关数据, 分析了叶片最大羧化速率与叶氮含量关系随不同植被功能型和时间的变化特征, 以及环境因子变化条件下最大羧化速率与叶氮含量关系的变化特征, 探讨了二者关系变异性的可能原因以及影响因子。结果表明: 1)不同功能型植物叶片的最大羧化速率和叶氮含量的关系存在较大差异, 二者线性关系式的斜率平均值变化范围为16.29-50.25 μmol CO₂·g N^-1·s^-1。落叶植被叶片的最大羧化速率随叶氮含量的变化率和光合氮利用效率一般都高于常绿植被, 其变异主要源于植物的比叶重和叶片内部氮素分配的差异。2)叶片最大羧化速率随叶氮含量的变化存在季节和年际变异。在没有受到水分胁迫的年份中, 叶片最大羧化速率随叶氮含量变化的速率一般在春季或夏季最高, 其季节变异与比叶重和叶氮在Rubisco的分配比例的季节变化有关。受到干旱的影响, 叶片最大羧化速率随叶氮含量的变化率会升高。3)当大气CO₂浓度增加时, 由于叶片中Rubisco含量的降低, 多年生针叶叶片最大羧化速率和叶氮关系斜率值会出现降低; 当供氮水平增加时, 叶片最大羧化速率和叶片氮含量均表现出增加趋势, 二者线性关系的斜率也相应增加。在此基础上, 该文指出在模拟叶片最大羧化速率与叶氮含量的关系时, 应考虑叶片比叶重和叶氮在Rubisco中的分配比例的季节变异、水分胁迫、大气CO₂浓度和供氮水平变化对二者关系的影响。囿于数据的有限性, 今后应进一步加强多因子控制实验研究, 深入探讨叶片最大羧化速率与叶氮含量关系的变异性机理, 并获得更系统的观测数据, 以助生态系统过程模型的改进, 提高模型的模拟精度。     

木兰科植物叶片光合系统耐热性与叶片形态及温度生态位的关系

全球气候变化背景下,极端高温事件日益频繁,对植物的生长、存活造成严重威胁,准确评估植物的耐热性,对物种保育和适应性预测具有重要作用。木兰科是中国亚热带常绿阔叶林的标志类群,也是被子植物基部类群,具有重要的生态价值和演化生物学地位,然而目前对其耐热性尚缺乏了解。该研究以种植于同质园的23种木兰科植物为研究对象,利用叶绿素荧光技术研究了叶片光合系统的耐热性,同时测定了叶片形态性状,并基于这些物种在全球的分布地气候数据,分析了叶片光合系统耐热性与叶片形态及温度生态位的关系。发现木兰科植物光系统II最大光化学效率降低50%时的温度(T50)范围在46.1–56.7℃之间,且常绿物种的T50显著高于落叶物种。叶片形态方面, T50与叶面积显著正相关,与叶片厚度无显著相关关系。温度生态位方面, T50与年平均气温、最冷月最低气温呈显著正相关关系,但与最暖月最高气温无显著相关关系。T50具有较弱的系统发育信号,暗示T50受系统发育影响较小,受叶片形态与环境气候的影响较大。研究结果说明木兰科植物的叶片光合系统耐热性较强,但耐热性的气候适应可能并不受高温环境驱动,未来的高温事件对生活于更炎热地区的木兰科...     

树木叶片面积与叶柄长、节间长和叶倾角的关系初探

树木的叶片面积与叶柄长、节间长之间有着明显的内在联系．本文分析研究了这个联系,在适当的理想假设下通过数学建模得到了反映树木叶片面积与叶柄长、节间长和叶倾角之间的关系模型．接着,文章对模型的不合理之处进行了分析与改进,并得到叶片面积与节间长、心茎距之间的关系表达式．最后,本文利用分别采集到的13种互生和对生树木叶子上的相关数据对模型进行了检验．检验结果表明建立的模型是正确的,能够反映树木的叶片面积与叶柄长、节间长和叶倾角之间的相互数量关系．     

红树林植物叶片形态和解剖特征对叶肉导度、叶片导水率的影响

叶肉导度和叶片导水率是影响光合作用的两个重要过程,叶肉导度通过影响从气孔下腔到Rubisco酶位点的二氧化碳浓度梯度直接影响光合作用,而叶片导水率则通过影响水分供应或气孔行为来影响光合作用,然而对这两个生理过程之间的协同性研究较少。本研究选择9种红树林植物为研究对象,探讨盐生环境下植物叶肉导度和叶片导水率的协同性及其与叶片解剖结构特征之间的相关性。结果表明,9种红树林植物叶片导水率(0.78~5.83 mmol·m~(-2)·s~(-1)·MPa-1)、叶肉导度(0.06~0.36 mol·m~(-2)·s~(-1))、最大光合速率(7.23~23.71μmol·m~(-2)·s~(-1))等特征的差别较大;叶肉导度与最大光合速率呈显著正相关,而与比叶重无显著相关性,其原因是由于比叶重与叶片厚度、叶片密度不存在相关性;叶脉密度与气孔密度呈较强的相关性,说明红树林植物叶片水分运输与散失相关的叶片结构之间存在协同关系;叶片导水率不受叶脉密度影响,并且与叶肉导度、最大光合速率也不存在相关性,这很可能与红树林植物叶片的肉质化、有发达的储水组织有关,体现了红树林植物叶片结构和功能的特殊性。     

Self-propulsion of dew drops on lotus leaves: a potential mechanism for self cleaning

This study shows that condensation on the hierarchically structured lotus leaf can facilitate self-propulsion of water droplets off the surface. Droplets on leaves inclined at high angles can be completely removed from the surface by self-propulsion with the assistance of gravity. Due to the small size of mobile droplets, light breezes may also fully remove the propelled droplets, which are typically projected beyond the boundary layer of the leaf cuticle. Moreover the self-propelled droplets/condensate were able to remove contaminants (eg silica particles) from the leaf surface. The biological significance of this process may be associated with maintaining a healthy cuticle surface when the action of rain to clean the surface via the lotus effect is not possible (due to no precipitation). Indeed, the native lotus plants in this study were located in a region with extended time periods (several months) without rain. Thus, dew formation on the leaf may provide an alternative self-cleaning mechanism during times of drought and optimise the functional efficiency of the leaf surface as well as protecting the surface from long term exposure to pathogens such as bacteria and fungi.     

基于冠层温湿度模型的日光温室黄瓜霜霉病预警方法

利用温室环境参数构建室内微环境模拟模型,并结合温室病害模型进行预警,便于开展病害生态防治,以减少农药使用,从而保护温室生态环境和保证农产品质量安全.本文利用温室内能量守恒原理和水分平衡原理,构建了日光温室冠层叶片温度和空气相对湿度模拟模型.叶片温度模拟模型考虑了温室内植物与墙体、土壤、覆盖物之间的辐射热交换,以及室内净辐射、叶片蒸腾作用引起的能量变化;相对湿度模拟模型综合了温室内叶片蒸腾、土壤蒸发、覆盖物与叶面的水汽凝结引起的水分变化.将温湿度估计模型输出值作为参数,输入黄瓜霜霉病初侵染和潜育期预警模型中,估计黄瓜霜霉病发病日期,并与田间观测的实际发病日期比较.试验选取2014年9月和10月的温湿度监测数据进行模型验证,冠层叶片温度实际值与模拟值的均方根偏差（RMSD)分别为0.016和0.024 ℃,空气相对湿度实际值与模拟值的RMSD分别为0.15%和0.13%.结合温湿度估计模型结果表明,黄瓜病害预警系统预测黄瓜霜霉病发病日期与田间调查发病日期相吻合.本研究可为黄瓜日光温室病害预警模型及系统构建提供微环境数据支持.     

湿度对柑桔潜叶蛾存活的影响

湿度对柑桔潜叶蛾存活的影响王联德尤民生（福建农业大学植保系,福州３５０００２）ＩｎｆｌｕｅｎｃｅｏｆＨｕｍｉｄｉｔｙｏｎｔｈｅＳｕｒｖｉｖａｌｏｆＣｉｔｒｕｓＬｅａｆＭｉｎｅｒ．ＷａｎｇＬｉａｎｄｅ,ＹｏｕＭｉｎｓｈｅｎｇ（ＦｕｊｉａｎＡｇｒｉｃｕｌ...     

不同形状城市湿地对周边环境温湿度的影响

2015年春、夏、秋季选择大庆市区5种不同形状特征的城市湿地及周边环境作为研究对象,利用小尺度定量测定的方法,分析城市湿地形状特征对周边环境温、湿效益的影响.结果表明: 不同形状特征的城市湿地均具有增湿降温效应.其中,夏季的增湿降温效应最强,春季其次,秋节最差.形状特征对湿地的降温增湿能力具有显著影响,不规则形状湿地>规则形状湿地(近圆形湿地、近矩形湿地)>长条形状湿地;增湿降温日变化受环境温度影响较大,即早晚弱、中午强,春、秋季增湿降温幅度最大的时段为12:00—14:00,夏季增湿降温幅度最大的时段为14:00—16:00.     

XET-related genes and growth kinematics in barley leaves

DV, displacement velocity
GA₃, gibberellic acid
REGR, relative elemental growth rate
XET, xyloglucan-endotransglycosylase

Recently Schünmann et al. (1997 ; Plant, Cell and Environment 20, 1439–1450) investigated the correlation of spatial patterns of xyloglucan-endotransglycosylase (XET) activity, XET-related mRNAs, and growth in elongating barley ( Hordeum vulgare L.) leaves. Here, methodological difficulties in the kinematic growth analysis are discussed, and it is concluded that the role that XET-related gene activity plays in the control of spatial growth patterns remains undetermined.     

苍耳柄锈菌三裂叶豚草专化型冬孢子萌发过程及萌发条件的研究

本文采用光学显微镜和扫描电子显微镜技术及荧光染色技术,对苍耳柄锈菌三裂叶豚草专化型Puccinia xanthii sp.ambrosiae-trifidae冬孢子的萌发过程和萌发条件进行了研究。结果表明:冬孢子堆成熟时突破寄主表皮外露;在寄主上冬孢子萌发时由上细胞顶部出现皱褶和帽状物,由帽状物下伸出担子。冬孢子的上细胞和下细胞都可萌发;冬孢子在水中于25℃2h即可萌发,24h后达到萌发高峰,萌发率为12%;温度20-25℃、相对湿度97%以上、pH5-7的条件利于冬孢子萌发,光照对冬孢子萌发没有影响,木糖和乳糖对冬孢子萌发有促进作用;无机氮源营养对冬孢子萌发有抑制作用。肌醇、烟酸、核黄素及三裂叶豚草叶汁对冬孢子萌发有促进作用。     

亚高温下不同空气湿度对番茄光合作用和物质积累的影响

为了研究亚高温下不同空气湿度对番茄植株光合作用及物质积累的影响,本试验利用人工气候室,在11:00—15:00平均温度为33℃的亚高温条件下,设置3个空气相对湿度处理,分别为70%～80%(高湿)、50%～60%(中湿)和不加湿的30%～40%(低湿)。结果表明:在处理25d时,高湿处理番茄叶片叶绿素含量、净光合速率显著高于低湿处理,而低湿处理果实空洞率比高湿处理高18.4%(P<0.05);在33℃亚高温条件下,70%～80%的相对湿度有利于光合作用的增强和果实品质的提高。     

Measuring dew formation and its threshold value for net radiation loss on top leaves in a paddy rice crop by using the dewball: a new and simple instrument

In a field experiment on dew formation in tropical paddy rice, the threshold value for the nocturnal net radiative loss required for dew formation was investigated during 23 nights from February to April 1994. The onset and cessation of dew were visually observed on both the top leaves of a rice crop and on a glass sphere, the ”dewball”, installed in the field 1.0 m above the ground. The threshold value for the nocturnal net radiative loss (R _n,thresh) necessary for dew formation on the ball was deduced from the maximum zenith angle on the ball surface reached by the dew formed. R _n,thresh was found to be linearly related to the nightly minimum vapour-pressure deficit. This linear relationship as well as the Penman-Monteith equation (an energy-balance approach) were used to predict both the time of dew onset and the duration of dew on the ball. These predicted values agreed well with the observed results. Dew duration and time of dew onset on the ball were well correlated. During most nights, dew began to form on the top leaf surfaces at almost the same time as it reached the zenith angle of 60° on the ball. A linear relationship was found between the observed daily duration of dew on the top leaf surfaces of the rice crop and the estimated time when dew reached the zenith angle of 60° on the ball. This relationship gave as accurate an estimation of dew duration on the top leaf surface of the rice crop as did the Penman-Monteith combination equation. This study showed that the dewball is a potentially useful device for observing dew formation. Received: 26 April 1999 / Revised: 8 May 2000 / Accepted: 9 May 2000     

The effect of gravity on surface temperatures of plant leaves

A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 degrees C, a relative humidity of 18% and an irradiance of 260 W m-2. Mean leaf temperatures increased by 0.9-1.0 degrees C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 degrees C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 degrees C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s-1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection.     

Manipulation of the hypocotyl sink activity by reciprocal grafting of two Raphanus sativus varieties: its effects on morphological and physiological traits of source leaves and whole‐plant growth

To reveal whether hypocotyl sink activities are regulated by the aboveground parts, and whether physiology and morphology of source leaves are affected by the hypocotyl sink activities, we conducted grafting experiments using two Raphanus sativus varieties with different hypocotyl sink activities. Comet (C) and Leafy (L) varieties with high and low hypocotyl sink activities were reciprocally grafted and resultant plants were called by their scion and stock such as CC, LC, CL and LL. Growth, leaf mass per area (LMA), total non‐structural carbohydrates (TNCs) and photosynthetic characteristics were compared among them. Comet hypocotyls in CC and LC grew well regardless of the scions, whereas Leafy hypocotyls in CL and LL did not. Relative growth rate was highest in LL and lowest in CC. Photosynthetic capacity was correlated with Rubisco (ribulose 1·5‐bisphosphate carboxylase/oxygenase) content but unaffected by TNC. High C/N ratio and accumulation of TNC led to high LMA and structural LMA. These results showed that the hypocotyl sink activity was autonomously regulated by hypocotyl and that the down‐regulation of photosynthesis was not induced by TNC. We conclude that the change in the sink activity alters whole‐plant growth through the changes in both biomass allocation and leaf morphological characteristics in R. sativus.