香紫苏开花期蒸腾和光合作用日变化特征及其影响因子研究

对开花期香紫苏功能叶片的蒸腾作用、光合作用日变化规律以及二者与环境因子之间的相互作用进行了研究.结果表明:处于花期的香紫苏蒸腾速率和气孔导度的日变化总体趋势是先升高后降低;不同花期净光合速率的日变化之间则存在明显的差别,初花期的净光合速率明显高于盛花期和终花期;湿度和光合有效辐射是影响香紫苏蒸腾作用的最主要因素,而光合有效辐射和CO2浓度变化则对香紫苏的净光合速率影响最大.     

长白山树木蒸腾和气孔阻力的日变化

1.多种树木蒸腾在清晨上升过程中有一个小的下降,而在傍晚蒸腾下降过程中又有一个小的回升;2.和低海拔处的同属树种相比,高山树种蒸腾强烈而气孔阻力终日低下,且此低气孔阻力与高光合能力相联系;3.叶片离体几分钟内蒸腾强度持续下降而看不到突然上升现象。     

田间小麦叶片光合效率日变化与光合“午睡”的关系

小麦灌浆初期叶片(旗叶)晴天中午光合速率下降(“午睡”)伴随了气孔导度、胞间CO_2浓度下降,而气孔限制值中午升高,进一步证实气孑L中午关闭是光合“午睡”的一个重要原因。叶片光合效率的中午下降并非都伴随着光合“午睡”现象。当两者同时发生时,胞间CO_2浓度降低,而光合速率与气孔导度、胞间CO_2浓度之间的相关性高于光合速率与光合效率之间的相关性。这些事实表明。即使光合效率中午下降是光合“午睡”的部分原因,但较之气孔中午关闭只是一个次要原因。     

半干旱雨养区小麦叶片光合生理生态特征及其对环境的响应

分析了黄土高原半干旱雨养农业区田间春小麦叶片光合生理生态特征及其对环境因子的响应。结果表明,天气晴朗时,净光合速率日变化呈典型的双峰曲线,有“午休”现象,上午明显高于下午,且不同生育期峰值出现的迟早不同。蒸腾速率日变化呈不明显的双峰型,其出现最大值的时间晚于净光合速率出现最大值的时间。在生长季节,叶片净光合速率、蒸腾速率和气孔导度均受到多个环境因子的共同影响。不同时期,起主导作用的环境因子不同,且同一个因子对几个生理指标的影响程度和强度都有差异,其中,光合有效辐射是对蒸腾速率影响最强烈的环境因子,湿度对光合作用的影响大于温度。受环境因子制约最为显著的生理指标是叶片的蒸腾速率和气孔导度。     

大豆光合日变化过程中气孔限制和非气孔限制的研究

研究了在典型高温低湿天气下大豆光合日变化过程中气孔限制和非气孔限制的效应。大豆叶片在中午表现出严重的气孔关闭伴随着光合速率的大幅度下降,但中午光合速率下降期间,大豆叶片细胞间隙的CO_2浓度不但没有下降反而有所增加,同时气孔限制值也在下降。实验结果表明,大豆叶片的光合午休现象主要是因为大豆叶片的羧化效率、光合能力,RUBP再生能力的下降以及CO_2补偿点升高造成的。大豆叶片在中午时气孔导度的下降不是造成光合午休的原因,而是在特定环境中实现水分利用最优的一种对策。     

光合作用-蒸腾作用-气孔导度的耦合模型及C_3植物叶片对环境因子的生理响应(英文)

以叶片的气体传输过程为基础,将蒸腾作用包括在以往光合作用气孔导度的耦合模型中,建立了光合作用蒸腾作用气孔导度的耦合模型。该模型可以模拟边界层导度对生理过程的影响。模拟了Ｃ３植物叶片对环境因子,如光照、温度、湿度、边界层导度和ＣＯ２浓度等的生理响应（光合作用、蒸腾作用、气孔导度）以及Ｃｉ和水分利用效率的变化。在环境因子变化于较大范围的情况下,模拟结果符合许多实验结论。     

不同时期毛乌素沙区主要植物种光合作用和蒸腾作用的变化

 采用LI—6000便携式光合分析系统对毛乌素沙区主要植物种油蒿、中间锦鸡儿、旱柳进行了不同时期光合作用,蒸腾作用日进程的测定,并同步测定有效光辐射、空气相对湿度、叶温、气温、胞间CO2浓度、气孔阻力、叶片水势及土壤水势等因子;结果表明：不同时期、不同植物种其光合、蒸腾特征各异;植物的光合、蒸腾与环境因子和植物内部因子之间有密切关系,其中有效光辐射是影响光合作用、蒸腾作用诸因子中的主导因子,而气孔阻力变化则在调节光合和蒸腾中起着重要作用;不同植物种间气孔对环境条件变化的响应程度不同,以中间锦鸡儿最为灵敏;3种植物的水分利用效率表明,中间锦鸡儿的水分利用效率较油蒿、旱柳为高。     

珍稀药用植物白及光合与蒸腾生理生态及抗旱特性

以珍稀濒危药用植物白及(Bletilla striata)叶片为研究对象,应用Li-6400XT便携式光合仪分别在晴天和阴天进行光合生理生态特性研究。结果显示晴天Gs、Pn、Tr日变化呈现双峰型,阴天为单峰型;光合-蒸腾具有极显著线性正相关关系与良好的线性耦合关系(晴天和阴天的相关系数分别为0.883^**、0.954^**,回归直线斜率分别为2.38、3.78);PAR-Pn与PAR-Tr、Tl-Pn与Tl-Tr、Gs-Pn与Gs-Tr 的回归直线形态非常相似,除晴天Tl与Pn外,其余两两相关关系均达到了显著水平;PAR、Tl和Gs三个因子与Pn、Tr均表现为正相关关系,其中Gs是调控Pn与Tr的最主要因子。进行聚乙二醇6000(PEG6000) 渗透胁迫实验以评价白及抗旱能力,分析不同质量分数PEG6000(0、5、20、40、60g/L)下的白及幼苗叶绿素含量、叶片含水量、相对电导率3个生理指标,结果表明叶绿素含量与与胁迫浓度呈负相关(R²=0.7854),随着PEG质量分数的增加,叶片的叶绿素含量持续显著下降;叶片含水量与胁迫浓度呈负相关(R²=0.9936);相对电导率与与胁迫浓度呈正相关(R²=0.8755),相对电导率会随着PEG质量分数的增加而显著增加。试验结果综合分析显示白及为耐荫植物,抗旱能力不强。白及进行人工栽培应适当遮阴保持土壤与空气湿度。     

水分胁迫下植物叶片光合的气孔和非气孔限制

评述了水分胁迫下植物叶片光合的气孔和非气限制研究的进展,提出了一个判别水分胁迫下气孔和非气孔限制的方法。     

Effects of potassium deficiency on water relations and photosynthesis of the tomato plant

Potassium deficient (−K) and potassium sufficient (+K) plants were exposed to four days of water stress. Well watered −K and +K plants had comparable rates of transpiration. But +K plants had a larger leaf area and depleted the soil moisture to a greater extent on day 1 of stress. For days 2 and 3 their transpiration rate, leaf water potential and relative water content fell below those of −K plants. Well watered −K plants had a significantly lower rate of photosynthesis than +K plants. Photosynthesis of −K plants was more sensitive to reduction in plant water potential than that of +K plants. Reduction of photosythesis in −K leaves was due to impairment of photosynthetic capacity and not to stomatal closure. Growth was significantly reduced in −K plants.     

沙柳光合作用和蒸腾作用日动态变化的初步研究

沙柳是毛乌素沙地流动沙丘和固定沙丘上广泛分布的重要固沙植物。叶片的光合速率呈现出不规则的日动态变化 ,在 1 0 :0 0～ 1 1 :0 0及 1 4 :0 0出现光合午休现象。蒸腾速率呈现出单峰型的日动态变化 ,蒸腾在午后 1 5:0 0达到最大。水分利用效率在早晨 9:0 0后保持在 2～ 2 .5μmol CO2 · mmol-1 H2 O左右。叶片水分亏缺也表现出规律性的变化。从早晨开始 ,叶片水分亏缺逐渐增大 ,在 1 8:0 0达到最大值。比较生长季节的不同时期环境因子的变化情况表明 ,春末的光照强度和气温比夏末高 ,但土壤水分含量则相反。沙柳在春末的光合速率、蒸腾速率分别是夏末的 79%和 72 .4% ,表明水分亏缺是影响沙柳生长发育的主要限制因素。沙柳在不同季节对水分的不同利用特点是对环境胁迫的弹性适应     

The adaptive significance of amphistomatic leaves

Abstract A clear correlation between the presence of stomata on both surfaces and factors such as habitat, growth form, and physiology has yet to emerge in the literature. However, certain loose trends with these factors are evident, and these are reviewed along with evidence for hypostomaty as the primitive form. It is proposed that the effect of developing stomata on the upper surface as well as the lower is to increase maximum leaf conductance to CO₂. Plants with a high photosynthetic capacity, living in full-sun environments, and experiencing rapidly fluctuating or continuously available soil water (as opposed to seasonal or long-term soil water depletion), are identified as deriving an adaptive advantage from a high maximum leaf conductance. The correlation between groups of plants fitting the above conditions and those noted to be amphistomatic is remarkable. Plants not fitting the conditions are found to be largely hypostomatic.     

Isolation and characterization of variant wheat cultivars for ABA sensitivity

Genetic variants for abscisic acid (ABA) sensitivity are important for investigating the role of ABA sensitivity in conditioning plant response to environmental stress, and especially to those soil conditions that may elicit a root-mediated hormonal signal. This study was performed in order to isolate variation in ABA sensitivity among wheat (Triticum aestivum and T. durum) cultivars, as characterized by two plant responses: (i) shoot growth reduction in response to 5×10^?2mol m^?3 ABA (racemic) in the root medium of hydroponically grown plants, and (ii) changes in transpiration and gas exchange in a bioassay of detached leaves (leaflaminac) infused with 10^?4mol m^?3 ABA. Very significant (P≤0.01) and repeatable differences were found among 36 wheat cultivars and 19 landraces in the growth rate in ABA-containing nutrient solutions, expressed as a percentage of the growth rate in control nutrient solutions (ABA/control ratio). In duplicate experiments, the ABA/control ratio ranged between 60 and 83% for the least sensitive cultivars (V2151-3, Bethlehem, K1056 and Sunstar) and between 9 and 19% for the most sensitive cultivars (Sundor, Comet, Barkaec and V5). In the transpiration bioassay, performed with seven selected cultivars, it was found that the reductions in transpiration of ABA-infused leaves corresponded very well with the reductions in growth in response to ABA in the root media. Measurement of gas exchange in the detached leaves of two cultivars differing in ABA sensitivity (Bethlehem and Sundor) showed that variable ABA sensitivity was expressed very well in the stomatal conductance, carbon exchange rate (CER) and photosynthetic capacity (CER/C_i ratio) of the leaf. These results therefore allowed us to isolate wheat variants for ABA sensitivity and to conclude that, while ABA sensitivity is expressed in the growth of plants challenged by ABA in the root medium, the control of sensitivity resides, at least partly, in the leaf.     

A hydromechanical and biochemical model of stomatal conductance

A mathematical model of stomatal conductance is presented. It is based on whole‐plant and epidermal hydromechanics, and on two hypotheses: (1) the osmotic gradient across guard cell membranes is proportional to the concentration of ATP in the guard cells; and (2) the osmotic gradient that can be sustained per unit of ATP is proportional to the turgor pressure of adjacent epidermal cells. In the present study, guard cell [ATP] is calculated using a previously published model that is based on a widely used biochemical model of C₃ mesophyll photosynthesis. The conductance model for Vicia faba L. is parameterized and tested As with most other stomatal models, the present model correctly predicts the stomatal responses to variations in transpiration rate, irradiance and intercellular CO₂. Unlike most other models, however, this model can predict the transient stomatal opening often observed before conductance declines in response to decreases in humidity, soil water potential, or xylem conductance. The model also explicitly accommodates the mechanical advantage of the epidermis and correctly predicts that stomata are relatively insensitive to the ambient partial pressure of oxygen, as a result of the assumed dependence on ATP concentration.     

Differential requirement for NO during ABA-induced stomatal closure in turgid and wilted leaves

Abscisic acid (ABA)-induced stomatal closure is mediated by a complex, guard cell signalling network involving nitric oxide (NO) as a key intermediate. However, there is a lack of information concerning the role of NO in the ABA-enhanced stomatal closure seen in dehydrated plants. The data herein demonstrate that, while nitrate reductase (NR)1-mediated NO generation is required for the ABA-induced closure of stomata in turgid leaves, it is not required for ABA-enhanced stomatal closure under conditions leading to rapid dehydration. The results also show that NO signalling in the guard cells of turgid leaves requires the ABA-signalling pathway to be both capable of function and active. The alignment of this NO signalling with guard cell Ca²⁺-dependent/independent ABA signalling is discussed. The data also highlight a physiological role for NO signalling in turgid leaves and show that stomatal closure during the light-to-dark transition requires NR1-mediated NO generation and signalling.     

不同生育期玉米叶片光合特性及水分利用效率对水分胁迫的响应

利用大型移动防雨棚开展了玉米水分胁迫及复水试验,通过分析玉米叶片光合数据,揭示了不同生育期水分胁迫及复水对玉米光合特性及水分利用效率的影响。结果表明:水分胁迫导致玉米叶片整体光合速率、蒸腾速率和气孔导度下降以及光合速率日变化的峰值提前;水分胁迫后的玉米叶片蒸腾速率、光合速率和气孔导度为适应干旱缺水均较对照显著下降,从而提高了水分利用效率,缩小了与水分充足条件下玉米叶片的水分利用效率差值;在中度和重度水分胁迫条件下,玉米叶片的水分利用效率降幅低于光合速率、蒸腾速率和气孔导度的降幅, 有时甚至高于正常供水条件下的水分利用效率;适度的水分胁迫能提高玉米叶片的水分利用效率,从而增强叶片对水分的利用能力,抵御干旱的逆境;水分亏缺对玉米光合速率、蒸腾速率及水分利用效率的影响具有较明显滞后效应,干旱后复水,光合作用受抑制仍然持续;水分胁迫时间越长、胁迫程度越重,叶片的光合作用越呈不可逆性;拔节-吐丝期水分胁迫对玉米叶片光合作用的逆制比三叶-拔节期更难恢复。     

气孔免疫的研究进展及展望

气孔长期以来被认为是植物病原菌入侵植物体内的被动通道,而最新的研究则表明气孔作为植物先天免疫的重要环节,在限制细菌入侵方面起到主动作用。这一发现也带动了植物免疫学,即植物气孔开合调控和植物免疫学交叉学科的快速发展。基于此,本文对气孔免疫的机制研究展开综述并对其对植物水分利用效率的影响进行展望。     

Stomatal Density and Bio-water Saving

Bio-water saving is to increase water use efficiency of crops or crop yield per unit of water input. Plant water use efficiency is determined by photosynthesis and transpiration, for both of which stomata are crucial. Stomata are pores on leaf epidermis for both water and carbon dioxide fluxes that are controlled by two major factors： stomatal behavior and density. Stomatal behavior has been the focus of intensive research, while less attention has been paid to stomatal density. Recently, a number of genes controlling stomatal development have been identified. This review summarizes the recent progress on the genes regulating stomatal density, and discusses the role of stomatal density in plant water use efficiency and the possibility to increase plant water use efficiency, hence bio-water saving by genetically manipulating stomatal density.