2. Prepare a set of 6 reagent bottles(set A), place 1 ml of each solution and some Methylene blue powder in each bottle, prepare another set of 6 reagent bottles(set B), and place 4 ml of each solution in each bottle 3. With a hole-punch, punch out around 50 small disks from several leaf samples, place the disks in a petri dish for later use 4. put 5-8 disks in each of 6 reagent bottles of set A, and cork the bottles. Make sure hat all the leaf disks are totally immerged in the sucrose solutions shake the bottle once in a while 5. After 30-60mins take some blue solutions from each of the set a bottles with an injection needle, insert the needle into the corresponding set b bottle containing the same concentration of sucrose solution Release a little fluid then observe the direction of fluid flow. If the direction of fluid-flow is upward, it indicates that the concentration of sucrose solution in set A bottle, which has leaf disks immerged in, has decreased due to the loss of water of leaf tissues. This result suggests that water potential of leaf tissue is higher that that of the sucrose solution it immerged in. otherwise, If the direction of fluid flow is downward, it suggests that water potential of leaf tissue is lower thatthat of the sucrose solution it immerged in if the fluid does not move, it suggests that water potential of leaf tissue equals to that of the sucrose solution it immerged in 6. Using the information obtained and the following formula, calculate the water pressure of the leaf tissue 中w=中x=-CRT×1.013×0.1.中w= water potential of leaf tissue(Mpa),中 osmotiC potential of sucrose solution, C=concentration of cooresponding sucrose solution (molL-1), as constant 0.008314MPa/L/mol/KADsglutE*emperature lonization coefficient 1), I atmosphere standard= 1.013=0.1MPa. Discussion 1. What was the driving force for water movement(uptake or loss) and how was it generated? 2. Was water movement(uptake or loss )active or passive? Can we ignore P? Why or why not?
2. Prepare a set of 6 reagent bottles (set A), place 1 ml of each solution and some Methylene blue powderin each bottle, prepare another set of 6 reagent bottles (set B), and place 4 ml of each solution in each bottle. 3. With a hole-punch, punch out around 50 small disks from severalleaf samples, place the disks in a petri dish for later use. 4. put 5~8 disks in each of 6 reagent bottles of set A, and cork the bottles. Make sure that all the leaf disks are totally immerged in the sucrose solutions; shake the bottle once in a while. 5. After 30-60mins, take some blue solutions from each of the set A bottles with an injection needle, insert the needle into the correspondingset B bottle containing the same concentration of sucrose solution. Release a little fluid; then observe the direction of fluid –flow. If the direction of fluid –flow is upward, it indicates that the concentration of sucrose solution in set A bottle, which has leaf disks immerged in, has decreased due to the loss of water of leaf tissues.This result suggests that water potential of leaf tissue is higher that that of the sucrose solution it immerged in. otherwise, If the direction of fluid –flow is downward, it suggests that water potential of leaf tissue is lower that that of the sucrose solution it immerged in; if the fluid does not move, it suggests that water potential of leaf tissue equals to that of the sucrose solution it immerged in. 6. Using the information obtained and the following formula, calculate the water pressure of the leaf tissue. ψw＝ψ ＝－iCRT×1.013×0.1. ψw＝water potential of leaf tissue（Mpa）,ψ ＝osmoticpotential of sucrose solution，C＝concentration of cooresponding sucrose solution（mol•L-1），R＝ 0.008314MPa/L/mol/K），T＝ i＝ sucrose＝ 1） , 1 atmosphere standard＝ 1.013＝ 0.1MPa. Discussion 1. What was the driving force for water movement (uptake or loss) and how was it generated? 2. Was water movement (uptake or loss) active or passive? Can we ignore ΨP? Why or why not? 21 π Gas constant（ Absolute temperature， Ionization coefficient（ π
实验3水分在植物体维管束內的运输途径和机制 【实验目的】 通过实验·加深对水分在植物体內运输的途徑与速度及维管束运输潜力的认识 学会如何测定水势。在本实验中·你将观案到水分在向日葵( Helianthus annuus)中 的运输的途径和机制,学习如何用一个压力室来控制水势 【实验原理】 在植物中的水分运输·包括木质部的蒸腾作用·是由水势梯度拉动的。水分从 叶表细胞中蒸发产生一个拉力(叶表面细胞水势降低·产生一个负压)·叶细胞中较 低的水势·带动整个植株形成一个水势梯度·从而引趄水分由下往上运输。因为水 分是由高水势向低水势流动的虽然水分向下运动是自发的·但是水分实际上是向上 移动的。为了对不同的水势的对比·我们捋不给这些植物提供水·使它们达到膨压 损失点。由于向日葵是草本植物·缺乏广泛的木质仁·所以它的萎蔫的点可以被看 作达到膨压损失点。另外·本实验捋比较一年生草本植物向日葵和一种木本植物 ( Lycopersicon esculentum原产于加利福尼亚州查帕拉尔多年生灌木)的水势的不 同。查帕拉尔多年生灌木是一种耐旱植物·它与向日葵相比可以在更低的水势环境 生存。 【实验材料】 向日葵或西红柿植株·1/3到1/2m高(一半是水分充足的植株·一半是萎蔫 的植株)。 【设备与试剂】 亚甲蓝染液(亚甲蓝溶于水)·手推车上的金属卤化灯·滤水器(用于阴天时使 植物保持萎蔫)·锋利的刀片(每组一个)·无尘擦拭纸或者纸巾·压力室·手电筒 放大镜·加压氮气罐和必要的配件·解剖镜·橡胶或塑料手套·密封塑料袋·有冰 的小冰盒(每组一个) 【实验步骤】 (1)学生捋两人一组。分给每组两株植物·一株水分充足的·一株是萎蔫的或 是快萎蔫的。选择一株植物的接近顶端的相邻的一对叶子作初始量。一片叶子用于
实验 3 水分在植物体维管束内的运输途径和机制 【实验目的】 通过实验，加深对水分在植物体内运输的途径与速度及维管束运输潜力的认识， 学会如何测定水势。在本实验中，你将观察到水分在向日葵（Helianthus annuus）中 的运输的途径和机制，学习如何用一个压力室来控制水势。 【实验原理】 在植物中的水分运输，包括木质部的蒸腾作用，是由水势梯度拉动的。水分从 叶表细胞中蒸发产生一个拉力（叶表面细胞水势降低，产生一个负压）。叶细胞中较 低的水势，带动整个植株形成一个水势梯度，从而引起水分由下往上运输。因为水 分是由高水势向低水势流动的虽然水分向下运动是自发的，但是水分实际上是向上 移动的。为了对不同的水势的对比，我们将不给这些植物提供水，使它们达到膨压 损失点。由于向日葵是草本植物，缺乏广泛的木质化，所以它的萎蔫的点可以被看 作达到膨压损失点。另外，本实验将比较一年生草本植物向日葵和一种木本植物 （Lycopersicon esculentum 原产于加利福尼亚州查帕拉尔多年生灌木）的水势的不 同。查帕拉尔多年生灌木是一种耐旱植物，它与向日葵相比可以在更低的水势环境 生存。 【实验材料】 向日葵或西红柿植株，1/3 到 1/2 m高（一半是水分充足的植株，一半是萎蔫 的植株）。 【设备与试剂】 亚甲蓝染液（亚甲蓝溶于水），手推车上的金属卤化灯，滤水器（用于阴天时使 植物保持萎蔫），锋利的刀片（每组一个），无尘擦拭纸或者纸巾，压力室，手电筒， 放大镜，加压氮气罐和必要的配件，解剖镜，橡胶或塑料手套，密封塑料袋，有冰 的小冰盒（每组一个）。 【实验步骤】 （1）学生将两人一组。分给每组两株植物，一株水分充足的，一株是萎蔫的或 是快萎蔫的。选择一株植物的接近顶端的相邻的一对叶子作初始量。一片叶子用于
测量水势·另一片叶子用于检测水分运输在解剖学上的路柽。不用把植物从它的光 环境移走·用锋利的刀片捋这对叶子中的一片从它的腋芽部分切去·并迅速把切叶 运送入测量叶水势的压力室。你的老师将教你如何使用压力室。 注意∶如果不能正确使用压力室·它是很危险的。在操作之前必须掌握其操作 方法并理解工作原理。在操作压力室过程中·必须始终戴着防护眼镜·眼睛不要直 接在压力室的上面 (2)当你得到水势值的时候·把它记录在你的笔记本上。然后·翻转植株把另 一片叶子的叶柄浸泡在亚甲基蓝染液中。保持叶柄还在染液下·用刀片从叶柄的基 部切下·在操作过程中要戴上手套并避免染液飞溅到衣服上。从把叶柄切下开始计 时·把叶柄的切口端浸泡在染液中1分钟·然后拿出叶子·小心的吸去多余的染液 (戴着手套·用无尘擦拭纸或纸巾)。 (3)快速把染色的叶子转移到解剖镜里·观察叶柄的切口端·哪里被染液渗透 了?沿着染液渗透的路线·对叶柄做一个纵切面。用尺子(单位mm)测量染液渗 透的长度·并把数值记录在你的笔记本上 (4)对你的第二棵植物重复上述操作 在你的笔记本上准备两个表格·分别记录水势的大小(单位Mpa)和染液渗透 的长度(单位mm)。然后把你们组的数据记到班级数据记录上(老师将帮助你们建 立一个班级数据记录)。记住要抄一份班级数据记录。 作业 A)根据班级数据记录·制作一个整洁的表格(表1)总结这些数据。表格要包 括每组的数据和平均值(+标准俑差)·并有简明的描迹介绍 B)用一个条形图总结表1的数据(+标准偏差或标准误)。表格要有简明的描 述介绍 C)交一份简短的包括相尖的图表和数据的实验报告(<2页,包括图表和数据)。 【讨论】 1.对于本实验中用的这种植物,多久可以观察到水压力引起的明显的现象?对 于查帕拉尔多年生灌木·也有相同的现象吗? 染液在叶柄中运行的距离和水势的大小有相关性吗
测量水势，另一片叶子用于检测水分运输在解剖学上的路径。不用把植物从它的光 环境移走，用锋利的刀片将这对叶子中的一片从它的腋芽部分切去，并迅速把切叶 运送入测量叶水势的压力室。你的老师将教你如何使用压力室。 注意：如果不能正确使用压力室，它是很危险的。在操作之前必须掌握其操作 方法并理解工作原理。在操作压力室过程中，必须始终戴着防护眼镜，眼睛不要直 接在压力室的上面。 （2）当你得到水势值的时候，把它记录在你的笔记本上。然后，翻转植株把另 一片叶子的叶柄浸泡在亚甲基蓝染液中。保持叶柄还在染液下，用刀片从叶柄的基 部切下。在操作过程中要戴上手套并避免染液飞溅到衣服上。从把叶柄切下开始计 时，把叶柄的切口端浸泡在染液中 1分钟，然后拿出叶子，小心的吸去多余的染液 （戴着手套，用无尘擦拭纸或纸巾）。 （3）快速把染色的叶子转移到解剖镜里，观察叶柄的切口端。哪里被染液渗透 了？沿着染液渗透的路线，对叶柄做一个纵切面。用尺子（单位 mm）测量染液渗 透的长度，并把数值记录在你的笔记本上。 （4）对你的第二棵植物重复上述操作。 在你的笔记本上准备两个表格，分别记录水势的大小（单位 Mpa）和染液渗透 的长度（单位 mm）。然后把你们组的数据记到班级数据记录上（老师将帮助你们建 立一个班级数据记录）。记住要抄一份班级数据记录。 作业： A) 根据班级数据记录，制作一个整洁的表格（表 1）总结这些数据。表格要包 括每组的数据和平均值（+标准偏差），并有简明的描述介绍。 B) 用一个条形图总结表 1 的数据（+标准偏差或标准误）。表格要有简明的描 述介绍。 C) 交一份简短的包括相关的图表和数据的实验报告（<2页，包括图表和数据）。 【讨论】 1．对于本实验中用的这种植物，多久可以观察到水压力引起的明显的现象？对 于查帕拉尔多年生灌木，也有相同的现象吗？ 2．染液在叶柄中运行的距离和水势的大小有相关性吗？ 23
3.在这次练习中,用压力室测量木质部的水势时需要用压力室来估计一个压力 读数。这个估计的数是有效的吗? 4.与查帕拉尔多年生灌木相比,向日葵的水势是怎样的? 5.查帕拉尔多年生灌木是怎样保持非常低的水势而生存的? 6.如果记录的数据在统计学上有显著差异,你怎样确定?
3．在这次练习中，用压力室测量木质部的水势时需要用压力室来估计一个压力 读数。这个估计的数是有效的吗？ 4．与查帕拉尔多年生灌木相比，向日葵的水势是怎样的？ 5．查帕拉尔多年生灌木是怎样保持非常低的水势而生存的？ 6．如果记录的数据在统计学上有显著差异，你怎样确定？ 24
Experiment 3 Path and Mechanism of Water Transport In this lab, you will examine the mechanism and path of water movement in Helianthus annuus(sunflower) plants, and will learn how to determine water potential with a pressure chamber troduction Water movement in a plant, including transpirational movement in the xylem, is driven by water potential gradients. Evaporation from the leaves creates negative pressure)in the leaves. This lowers the leaf water potential, setting up a water potential gradient within the plant, and causing water to move up the plant. Although water actually moving uphill, we say that water is moving downhill energetically, because it is moving from regions of high water potential to regions of low water potential. To provide contrasting water potentials, we will withhold water from some plants, allowing them to reach the point of turgor loss. Because sunflower plants are herbaceous and lack extensive lignification, this point of turgor loss is readily seen as leaf wilting. An additional part of this lab will compare the water potential of sunflowers, which are herbaceous annuals, to woody perennial shrubs native to the California chaparral Chaparral plants are well-adapted to drought, and can often survive at water potentials much lower than those found in herbaceous annuals Materials needed Helianthus annuus(sunflower )or Lycopersicon esculentum(tomato) plants, 1/3 to 1/2 m tall(half well-watered, and half at the wilting point) Equipment and chemicals needed Methylene blue dye solution(methylene blue in H20), Metal halide lamps on cart with water filters(needed if cloudy to maintain plants in wilted state), Sharp razor blades (one per team), Kimwipes or paper towels, Pressure chamber(Plant Water Status Console, Soil Moisture Equipment Corporation, Santa Barbara, CA) with flashlight, magnifying lens, Pressurized nitrogen gas tank and necessary fittings, Dissecting scopes, Rubber or plastic gloves, Sealable plastic bags (e.g. ziploc), Small ice chests with ice (one per
Experiment 3Path and Mechanism of Water Transport Goals In this lab, you will examine the mechanism and path of water movement in Helianthus annuus(sunflower) plants, and will learn how to determine water potential with a pressure chamber. Introduction Water movement in a plant, including transpirational movement in the xylem, is driven by water potential gradients. Evaporation from the leaves creates a tension (negative pressure) in the leaves. This lowers the leaf water potential, setting up a water potential gradient within the plant, and causing water to move up the plant. Although water is actually moving uphill, we say that water is moving downhill energetically, because it is moving from regions of high water potential to regions of low water potential. To provide contrasting water potentials, we will withhold water from some plants, allowing them to reach the point of turgor loss. Because sunflower plants are herbaceous and lack extensive lignification, this point of turgor loss is readily seen as leaf wilting. An additional part of this lab will compare the water potential of sunflowers, which are herbaceous annuals, to woody perennial shrubs native to the California chaparral. Chaparral plants are well-adapted to drought, and can often survive at water potentials much lower than those found in herbaceous annuals. Materials needed Helianthus annuus (sunflower) or Lycopersicon esculentum (tomato) plants, 1/3 to 1/2 m tall (half well-watered, and half at the wilting point) Equipment and chemicals needed Methylene blue dye solution (methylene blue in H2O) , Metal halide lamps on carts with water filters (needed if cloudy to maintain plants in wilted state) ,Sharp razor blades (one per team) ,Kimwipes or paper towels,Pressure chamber (Plant Water Status Console, Soil Moisture Equipment Corporation, Santa Barbara, CA) with flashlight, magnifying lens, Pressurized nitrogen gas tank and necessary fittings, Dissecting scopes, Rubber or plastic gloves, Sealable plastic bags (e.g. ziploc), Small ice chests with ice (one per team)