植物叶片面积的图像信息测量系统及方法

利用TWAIN标准对原植物叶片面积测量系统进行了改进，使其可以直接从支持TWAIN标准的数字化图像输入设备读取图像数据．当采用扫描仪作为图像输入设备时，可以利用图像信息进行测量，而不必再对系统进行标定．     

Maize leaf elongation: continuous measurements and close dependence on plant water status

A simple method was developed for measuring extensive intact leaves of monocots on a minute-by-minute basis. Growth was markedly reduced by a slight reduction in leaf water potential. When plants mildly deficient in water were irrigated, growth resumed virtually instantly. The transitional rapid growth aftr watering suggests that water deficit increased cell extensibility.     

3 种草坪草叶片的水分吸收特性研究

采用草坪草活体浸水试验方法,研究3 种草坪草叶片在降雨截留发生时对截留在叶片表面水分的吸收过程, 并通过小尺度草坪及其与叶面积的关系获得了草坪草群体的最大吸水能力。结果表明,叶片吸水速率随时间变化 呈现幂函数关系,前期增长迅速,后期增长缓慢。3 种草坪草单位叶面积和单位干物质的最大吸水量存在差异,高 羊茅的单位叶面积叶片饱和质量最大,而单位干物质饱和质量最大的是早熟禾。得到了3 种草坪群体冠层叶片吸 水量与修剪高度之间的关系。      

水稻叶片营养的光谱诊断研究

通过测定不同氮肥水平下2个水稻品种的叶片营养数据和光谱数据,分析了遥感参量与叶片营养参数间的相关性.结果表明:在400～1 250 nm波段,叶片光谱反射率与SPAD、CHL呈显著负相关;在720～1 000 nm和1 450～1 500 nm波段,叶片光谱透射率与LWC间呈显著正相关;在400 ～ 650 nm波段,叶片光谱吸收率与CHL、SPAD和CAR呈显著正相关;分别构建了以NDVI、NDWI、GreenNDVI和NRI为自变量、叶片营养为因变量的光谱诊断模型,经检验,模型预测性较好,尤其利用NDWI(860,1 240)诊断LWC具有相对最大R2、最小RMSE和最小RE,表明此模型预测能力最强.     

Prediction of plant water status in almond and walnut trees using a continuous leaf monitoring system

Persistent drought conditions in the Central valley of California demands efficient irrigation scheduling tools such as precision or variable rate irrigation (VRI). To assist VRI scheduling, an experiment was conducted in almond and walnut orchards using a sensor system called ‘leaf monitor’, which was developed at UC Davis to detect plant water status. A Modified Crop Water Stress Index (MCWSI) was calculated to quantify plant water status using leaf temperature and environmental data collected by the leaf monitor. This technique also took into account spatio-temporal variability of plant water status. Stem water potential (SWP), which is considered a standard method for determining plant water stress (PWS), was also measured simultaneously. Relationships between measured deficit stem water potential (DSWP), which is the difference between SWP and the saturated baseline, and MCWSI were developed for both crops based on data collected during the 2013 and 2014 growing seasons. A linear relationship was found in the case of walnut crop with a coefficient of determination (r²) value of 0.67. A quadratic relationship was found in the case of almonds with a coefficient of multiple determination (R²) value of 0.75. Moreover, these results highlighted that at lower PWS of below 0.5 MPa of DSWP, almonds crops did not show any decrease in transpiration rate. However, when the stress level exceeded 0.5 MPa of DSWP, transpiration rate tended to decrease. On the other hand, walnut crop showed decrease in transpiration rate even at low PWS of below 0.5 MPa of DSWP. Temporal variability was noticed in PWS as it was found that coefficients of saturation baseline used for MCWSI method changed significantly throughout the season. MCWSI values estimated before an irrigation event was used to calculate the irrigation amount for low frequency variable rate irrigation (VRI) based on the relationship found between MCWSI and DSWP, and VRI led to an average 39% reduction in water usage as compared to the fixed 100% ET replacement irrigation method for all trees. Based on the results, leaf monitor showed potential for use as an irrigation scheduling tool.

     

Mapping water status based on aerial thermal imagery: comparison of methodologies for upscaling from a single leaf to commercial fields

Aerial thermal remote sensing can provide a means for collecting spatial plant water status data. Many studies have shown their potential in irrigation management but the adaptation of this technology is not straight forward. In this paper, knowledge accumulated in recent years on thermal imagery analysis methodology for water status mapping is summarized aiming at indicating alternatives to calculate the Crop Water Stress Index (CWSI) for commercial scale water status mapping. Based on literature overview, four forms of wet-baselines to calculate CWSI were selected, namely: artificial wet reference surface, two theoretical calculations and a statistical bio-indicator. These baselines were used to calculate CWSI based on multi-temporal aerial thermal images of cotton fields. CWSI based on a statistical bio-indicator and one of the theoretical wet-baselines provided the best correlations. It is argued though that the statistical one is preferable since it includes the plant characteristics and it is farmer-friendly. Based on bio-indicators, leaf water potential maps of three commercial fields were produced on several dates through the season. Water status spatial patterns were not static and the effect of static factors like sandy soil patches also changed through the season. The maps show the importance of in-season variability mapping for rational irrigation management. To improve current variable-rate irrigation, the concept of in-season irrigation management zones (IMZ) based on thermal-images should be considered and integrated with the delineation of static irrigation IMZ.     

水分胁迫对4树种幼苗叶水势和持水力的影响

以皂荚(Gleditsia sinensis)、核桃(Juglans regia)、柿子(Diospyros kaki)和黑枣(Diospyros lotus)为材料,在田间持水量为80%、60%、40%和30%的条件下对4树种幼苗叶含水量、叶水势和叶持水力进行了研究。结果表明:严重水分胁迫下,4树种叶含水量降低幅度是核桃<柿树<皂荚<黑枣,核桃和柿树能够保持较高的叶水势,而皂荚和黑枣的叶水势则比较低;充足供水条件下,4树种叶持水力是皂荚>核桃>柿树>黑枣,水分胁迫诱导了皂荚、柿树和黑枣叶片持水力的提高,而耐旱的核桃却没有明显的变化。     

Root pressure and leaf water potential

Measurements with thermocouple psychrometers were made of the water potentials of leaves from sunflower and pepper plants which had stood overnight in the dark in nutrient solutions containing carbowax. Similar measurements on the solutions showed that they had lower water potentials than the leaves, although the plants were measurably transpiring. Evidence that root pressure plays a part in this inversion of water potential gradient is presented.     

菱角离散元粘结参数标定与剪切试验

针对菱角（Trapa bispinosa Roxb.）脱壳初加工装备设计与仿真分析时缺乏有效的离散元模型问题，开展菱角粘结离散元参数标定与样机试验工作。采用三维反求技术获取菱角轮廓模型，测取菱角本征参数及基本接触参数，得到菱角平均剪切力为352.95 N，并以此为标定目标，采用EDEM软件中的Hertz-Mindlin with bonding模型建立菱角离散元模型，通过单因素试验筛选粘结参数标定范围，由二水平析因试验、最陡爬坡试验筛选显著因素及其标定区间，设计响应面试验求解粘结参数，确定离散元模型中的最优粘结参数组合，开展旋转剪切仿真试验及样机验证试验。结果显示：仿真得到的菱角脱壳剪切力为352 N，与实际误差为0.269%；菱角剪切刀具为矩形，转速230 r/min时，剪切力最小值为93.20 N，与预测值92.99 N的误差为0.215%；样机试验中矩形刀具在转速为230 r/min时各项性能指标最优，表明建立的菱角离散元模型可靠。     

天津市杨树早期落叶病发生现状及防治对策

近几年,天津市速生杨栽培区大量发生早期落叶现象,本文分析了杨树早期落叶病的发病原因,提出了治理对策.     

干旱胁迫下平邑甜茶叶片差异表达蛋白分析

【目的】探究平邑甜茶在干旱胁迫下的蛋白应激反应,为苹果砧木抗旱分子改良提供参考。【方法】以苹果砧木平邑甜茶为试材,在正常灌水后对其进行干旱胁迫处理(Mh-GD),以持续灌水为对照(Mh-CK),采用生理学和蛋白质组学相结合的研究方法,测定土壤水势、黎明前叶水势、光合作用及其叶片荧光参数,运用iTRAQ技术筛选鉴定响应干旱胁迫的差异表达蛋白,并对成功鉴定的蛋白进行GO注释及参与KEGG通路的分析。【结果】(1)与MhCK处理相比,Mh-GD处理平邑甜茶叶片相对含水量(RWC)、黎明前叶水势(ψleaf)、光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)均显著下降。(2)Mh-GD处理植株叶片PSⅡ的最大光合效率(Fv/Fm)、潜在活性(Fv/F0)、性能指标(PI)、单位反应中心吸收的光能(ABS/RC)均降低,而荧光动力学曲线升高。(3)运用iTRAQ技术共鉴定出1 897个蛋白,其中181个蛋白质表达量在Mh-CK、Mh-GD处理叶片间有显著差异,上调蛋白81个(P0.05,差异倍数1.5),下调蛋白100个(P0.05,差异倍数0.67)。181个蛋白中,86个蛋白功能已知,95个蛋白功能未知;已知功能可归为10类。【结论】在干旱胁迫下,平邑甜茶的差异表达蛋白质主要参与了光合作用、抗逆、信号转导和碳代谢等过程。     

基质栽培黄瓜叶片水分状况、光合与荧光参数对不同灌水下限的响应

为探明基质栽培黄瓜适宜的灌水下限,实现农艺节水,以黄瓜品种博特209为试材,采用基质盆栽,共设置4个灌水下限处理,即田间持水量的50%、60%、70%、80%,用A、B、C、D表示,灌水上限统一设定为田间持水量的90%,采用TDR350水分速测仪控制基质的水分含量,研究不同灌水下限对基质栽培黄瓜叶片水分状况、光合日变化及荧光参数的影响。结果表明:随着灌水下限的提高,叶片的相对含水量、自由水含量及自由水/束缚水的比值呈逐渐上升的趋势,水分饱和亏、叶片细胞汁液浓度及束缚水含量则呈下降趋势,处理C、D的相对含水量、自由水含量均显著(P<0.05)高于处理A、B,处理A细胞汁液浓度显著高于处理C、D,处理A、B束缚水含量显著(P<0.05)高于处理C、D。叶绿素a、叶绿素b和叶绿素a+b的含量均随灌水下限的升高呈现为先上升后下降的趋势,而类胡萝卜素含量则表现为先下降后上升的趋势,处理C叶绿素a、叶绿素a+b含量显著(P<0.05)高于处理A、B;处理C、D黄瓜叶片的胞间二氧化碳浓度(C_i)的变化趋势基本呈“V”型,而处理A、B的Ci的变化趋势基本呈“W”型;处理A、B、C、D的蒸腾速率(T_r)日变化均呈先上升后下降的趋势,处理B、C、D的Tr在14:00后呈现逐渐下降的趋势,而处理A在12:00后就呈快速下降的趋势;处理B、C、D的气孔导度(G_s)日变化大致呈“M”型的双峰曲线,处理A则呈单峰曲线;处理A、B、C、D叶片净光合速率(P_n)与G_s日变化趋势基本一致,在整个日变化过程中,处理C、D的P_n始终高于处理A、B。F_v/F_m、Φ_PSⅡ、qP随灌水下限的提高呈逐渐上升的趋势,而NPQ呈逐渐下降的趋势。研究结果表明,灌水下限为田间持水量的70%~80%,基质栽培黄瓜叶片的水分状况良好、光合色素含量高、净光合速率大,有利于黄瓜的光合作用,促进黄瓜的生长发育。     

水分胁迫对玉米叶片光合作用的影响

试验在盆栽人工控制水分的条件下,选用耐旱性不同的玉米杂交种沈单10、掖单13号和丹玉13号为试验材料,比较了不同水分胁迫强度对不同耐旱性玉米杂交种叶片光合作用的影响。结果表明,水分胁迫下玉米叶片光合速率随胁迫增强而下降,而在重度胁迫下光合速率显著下降。     

水分胁迫对不同基因型水稻叶片荧光特性的影响

为揭示水分胁迫下水稻叶片荧光特性下降的内在机制,在水培条件下以水稻幼苗为材料,研究了短时干旱胁迫下水稻叶片的荧光特性.结果表明,短时水分胁迫处理后荧光特性下降明显,0～30 min干旱荧光动力学参数,Fv/Fm,ΦPSⅡ,qp,NPQ有不同程度的变化,NPQ表现为小幅度的上升趋势,其它指标均降低,但下降的幅度一般都较小;Fv/Fm,ΦPSⅡ,Qp在胁迫处理90 min后下降的幅度加大,NPQ在120 min表现出开始下降的趋势,标志着叶片荧光特性受到明显影响.150 min短时胁迫处理过程中光合特性受到气孔限制和非气孔限制2个制约因素的共同作用,90～120 min光合机构的破坏是光合作用效率下降的主要原因.     

春玉米最大叶面积指数的确定方法及其应用

玉米叶面积指数达到最大时光合产物基本停止向营养器官分配,是玉米进入生殖生长阶段的标志.对锦州农田生态系统野外观测站2005-2011年多品种的春玉米大田试验资料分析发现春玉米最大叶面积指数出现于吐丝后2周左右,提出了春玉米叶面积指数达到最大时的积温指标,即播种至叶面积指数最大时的≥10℃有效积温为1085.3℃·d和(或)出苗至叶面积指数最大时的≥10℃有效积温为1010.4℃·d.在此基础上,采用修正的Logistic方程构建了春玉米相对叶面积指数动态普适模型.研究结果为准确模拟春玉米叶片生长及光合产物分配提供了依据.     

基于相位差的时域反射仪测定土壤含水量的标定和田间验证

为了检验具有我国自主知识产权的基于相位差检测原理的时域反射仪(TDR)测定土壤水分的性能,利用室内土柱试验,获得了该仪器测定土壤含水量的标定曲线,分析了影响因素,并在田间对标定曲线进行了实际验证。结果表明,容重对仪器测定土壤含水量的影响不显著;土壤质地对校正结果有明显影响,供试的砂质土类,壤质黏土类和黏土类分别可以使用一个特定标定公式,R2均大于0.98,估计标准误差均小于0.020cm3/cm3;该仪器用于田间测定含水量的均方根误差小于0.035cm3/cm3。因此,经过室内标定后,将新型时域反射仪用于测定田间土壤含水量是可靠的。     

基于叶片保水力的烟叶烘烤水分干燥模型构建

[目的]研究不同烟区、品种及部位烟叶保水力与水分干燥模型参数的关系,为烟叶烘烤提供简易、精准的水分预测方法并为烟草精准烘烤提供理论依据.[方法]以江西和湖南烟区烤烟品种K326和云烟87不同部位烟叶为试验材料,采用称重法测定烟叶保水力,结合水分干燥原理及水分干燥模型对烘烤过程中烟叶水分变化进行拟合求解,并对烟叶保水力与模型参数进行回归分析.[结果]不同部位间烟叶保水力随烟叶部位的升高而增加,不同品种间K326保水力均大于云烟87;除湖南烟区K326上部叶保水力大于江西烟区外,不同烟区间江西烟区烟叶保水力均大于湖南烟区.不同烟区、品种及部位烟叶Wang and Singh模型拟合决定系数R2均大于0.95,且模型干燥参数a与烟叶保水力呈正相关,与干燥参数b呈负相关.烟叶保水力与模型干燥参数a、b之间线性回归结果显示:烟叶保水力与模型参数a、b显著水平P均小于0.05,且线性拟合决定系数R2均大于0.95.[结论]常规烘烤过程中烟叶水分比变化符合Wang and Singh模型,且烟叶保水力与干燥模型参数a、b存在极显著相关,可依据烟叶保水力精准估算模型参数预测烟叶烘烤过程中水分变化.     

甜瓜光合特性对土壤水分条件的响应

以甜瓜品种‘银帝’和‘玉金香’为材料,设充分供水、轻度亏缺、中度亏缺3种水分处理,研究土壤水分条件对甜瓜开花-果实膨大期光合特性的影响.结果表明:在3个水分处理下,‘银帝’和‘玉金香’的净光合速率(Pn)日变化和气孔导度日变化(Gs)均表现为双峰曲线型,具有明显的光合"午休"现象.轻度和中度水分胁迫下,‘银帝’、‘玉金香’Pn显著降低,随水分亏缺程度加大,甜瓜叶片的蒸腾速率(Tr)呈下降趋势,瞬时水分利用效率(WUE)有所增加,表明轻度和中度水分亏缺能够提高甜瓜的水分利用效率.轻度、中度处理下,甜瓜叶片Pn下降以非气孔限制为主.各处理下甜瓜叶片Ci均呈现"下降-上升-下降-上升"的变化趋势,Ls的变化趋势则与Ci相反.在水分胁迫处理下,‘玉金香’叶片的Pn和WUE均高于‘银帝’,中度亏缺处理下,‘玉金香’日平均Pn和WUE分别比‘银帝’增加15.4%和8.2%,说明‘玉金香’的干旱适应性比‘银帝’强.