温室环境因子驱动甜瓜水分传输机理分析与模拟

利用人工气候室控制空气温度、相对湿度和光合有效辐射量,根据水量平衡法控制土壤含水率,按照四因素五水平的二次回归正交旋转组合设计,对甜瓜蒸腾量进行模拟,并探讨各因子调控水分传输的机制。基于Jarvis模型建立环境因素驱动的多元非线性气孔导度模型,结合水汽扩散原理建立蒸腾量模型,模型预测精度良好。探究因素交互作用及其耦合调控效应,结果表明:除相对湿度对蒸腾表现为抑制作用,土壤含水率、空气温度和光合有效辐射均对蒸腾具有促进作用;土壤含水率与空气温度的单因素效应相似,随因素水平增加,蒸腾量线性升高;光合有效辐射量驱动蒸腾的单因素效应为开口向下的二次函数,当因素水平超过阈值后,蒸腾量逐渐下降。环境因素在驱动和调控蒸腾过程中均存在密切耦合和反馈效应,土壤含水率与温度对蒸腾调控的耦合效应趋近于平滑曲面,蒸腾量随两因素水平的升高而升高,在试验水平内两因素对蒸腾表现为协同促进效应;空气相对湿度减弱了水汽扩散驱动力,进而抑制温度和土壤含水率对蒸腾的驱动作用,且这种抑制作用随相对湿度的升高而更明显。     

提高植物钾素利用效率的基因工程途径研究——以过表达ZmK2.1拟南芥为例

本文通过对13种植物（拟南芥，水稻，玉米，大豆，甜瓜，胡萝卜、葡萄、马铃薯、沙冬青、苜蓿、小花碱茅、黄瓜及杨树）中的Shaker型钾离子通道进行生物信息学聚类分析和氨基酸序列比对，选定C端区域反映C4植物特征的玉米气孔开放型钾离子吸收通道ZmK2.1，构建了过表达ZmK2.1的拟南芥株系（OE#3、OE#5、OE#11），同时以野生型Col-0为对照实验材料，研究过表达ZmK2.1拟南芥植株的钾素利用特征。实验采用固体培养基和水培培养相结合的方法，设置低钾（0.1 mol/L KCl）、中钾（1 mol/L KCl）及高钾（10 mol/L KCl）三个不同供钾水平，测定植株生物量、根长、钾含量、钾积累量、气孔导度、光合速率及蒸腾速率。研究结果：在钾充足条件下，过表达ZmK2.1拟南芥的根长、生物量、钾含量、钾积累量与对照相比，均显著增加。同时，过表达ZmK2.1基因的拟南芥气孔导度、光合速率、蒸腾速率显著提高。本研究结果表明：在供钾充足的条件下，通过基因工程手段过表达ZmK2.1基因可显著促进拟南芥植物的生长，并显著提高其钾素利用效率，这与ZmK2.1可显著增加植株的气孔导度，进而提高其光合效率和蒸腾速率密切相关。     

8种园林灌木光合特性及固碳释氧能力分析

以4种园林落叶灌木(火棘、锦带花、红瑞木、棣棠)和4种常绿灌木(红叶石楠、栀子、珊瑚树、金边黄杨)为材料，通过测定光合生理指标，分析树种的日固碳释氧能力，并对其单位叶面积日固碳量进行聚类分析。使用扫描电子显微镜观察叶表面气孔微形态，采用Pearson法分析各类灌木的日固碳量与叶面积、单株叶面积指数及气孔微形态的相关性。结果表明：(1)8种灌木光合速率日变化曲线呈“双峰型”或“单峰型”,除棣棠与金边黄杨之外，其他6种灌木均出现“光合午休”现象。(2)平均单位叶面积与单株单位土地面积上的日固碳释氧量均为：落叶树种>常绿树种。(3)8种灌木单位叶面积日固碳量聚类结果分为三类：第一类是日固碳量最高的锦带花和棣棠，第二类是日固碳量中等的金边黄杨、珊瑚树、红瑞木和火棘，第三类是日固碳量最低的栀子和红叶石楠。(4)单位叶面积日固碳量与叶面积或气孔大小呈正相关，单株单位土地面积上的日固碳量与单株叶面积指数或气孔大小呈正相关，且与气孔长度显著正相关(P<0.05)。因此，在城市绿化灌木的选择上，应充分参考其叶面积、单株叶面积指数及气孔微形态等指标，优先选择固碳释氧量较高的树种，以提升城市绿化...     

Variations in chlorophyll content,stomatal conductance,and photosynthesis in Setaria EMS mutants

Chlorophyll (Chl) content, especially Chl b content, and stomatal conductance (G_s) are the key factors affecting the net photosynthetic rate (P_n). Setaria italica, a diploid C₄ panicoid species with a simple genome and high transformation efficiency, has been widely accepted as a model in photosynthesis and drought-tolerance research. The current study characterized Chl content, G_s, and P_n of 48 Setaria mutants induced by ethyl methanesulfonate. A total of 24, 34, and 35 mutants had significant variations in Chl content, G_s, and P_n, respectively. Correlation analysis showed a positive correlation between increased G_s and increased P_n, and a weak correlation between decreased Chl b content and decreased P_n was also found. Remarkably, two mutants behaved with significantly decreased Chl b content but increased P_n compared to Yugu 1. Seven mutants behaved with significantly decreased G_s but did not decrease P_n compared to Yugu 1. The current study thus identified various genetic lines, further exploration of which would be beneficial to elucidate the relationship between Chl content, G_s, and P_n and the mechanism underlying why C₄ species are efficient at photosynthesis and water saving.     

考虑植被类型的冠层气孔导度模型

冠层气孔导度指示着植物的光合和蒸腾作用的强弱,冠层气孔导度的精确估算对于研究蒸散、农业生产和生态系统的功能等具有重要意义。以往冠层气孔导度的模型很少考虑植被类型的影响,而不同植被类型间冠层气孔导度存在较大差异,本研究旨在考虑植被类型,引入气孔长度和密度计算最大气孔导度,建立植被冠层气孔导度模型。使用HJ-1卫星数据反演了2012年7-9月黑河流域植被冠层气孔导度分布,基于地面实测数据对卫星反演的冠层气孔导度进行验证,结果表明,与改进前未区分植被类型的模型相比,决定系数由0.51提高至0.70,均方根误差由4.91mm/s下降至3.32 mm/s。改进模型可以描述植被类型间冠层气孔导度的差异,如2012年7月27日反演获得的玉米冠层气孔导度均值为15.12 mm/s,而云杉的冠层气孔导度均值则为3.84 mm/s。研究可为地表能量平衡和碳水循环等科学研究及精细农业、水资源管理等应用提供便利。     

干旱-复水对构树叶片水势和气孔开闭的影响

为探究干旱-复水对构树(Broussonetia papyrifera L.)叶片水势和气孔导度及其相关关系的影响，本研究以贵州贞丰(GZ)、河南周口(HN)、山东菏泽(SD)3个种源构树2年生幼苗为研究对象，研究不同干旱胁迫强度下构树叶片水势和气孔导度的变化特征。结果表明：干旱强度、干旱时间、种源及三者的交互作用均对构树叶片水势和气孔导度有显著影响。随着干旱胁迫强度的增强，GZ种源构树叶片水势显著降低，干旱胁迫指数明显增大，相较于对照(CK),轻度干旱(LS)、重度干旱(SS)处理下HN和SD种源构树叶片水势呈现先下降后上升的趋势。SS处理下各种源构树气孔导度显著低于CK。复水后，3个种源构树叶片水势和气孔导度均能恢复到CK水平。因此，干旱尤其是重度干旱显著降低了各种源构树水势和气孔导度，复水后均可恢复至正常供水水平，甚至出现超补偿生长。     

Air pollution removal through deposition on urban vegetation: The importance of vegetation characteristics

Urban vegetation has the potential to improve air quality as it promotes pollutant deposition and retention. Urban air quality models often include the effect vegetation have on pollution dispersion, however, processes involved in pollution removal by vegetation are often excluded or simplified and does not consider different vegetation characteristics. In this systematic review, we analyze the influence of the large interspecies variation in vegetation characteristics to identify the key factors affecting the removal of the major urban pollutants, particulate matter (PM) and nitrogen dioxide (NO₂) from the air through vegetation deposition. The aim is to identify key processes needed to represent vegetation characteristics in urban air quality modelling assessments.We show that PM is mainly deposited to the leaf surface, and thus representation of characteristics affecting the aerodynamics from canopy down to leaf surface are important, such as branch/shoot complexity and leaf size, leaf surface roughness and hairiness. In addition, characteristics affecting PM retention capacity, resuspension and wash-off, include leaf surface roughness, hairiness and wax content. NO₂ is mainly deposited through stomatal uptake, and thus stomatal conductance and its responses to environmental conditions are key factors. These include response to solar radiation, vapour pressure deficit and soil moisture.Representation of these vegetation characteristics in urban air quality models could greatly improve our ability to optimize the type and species of urban vegetation from an air quality perspective.