Procedure Students will work in teams of two. Each team will be assigned two sunflower plants. one well-watered. and one that has had water withheld and is at or near the wilting point. Select one plant for initial measurement, and choose a pair of adjacent, well-expanded leaves near the top of the plant. One leaf will be used for water potential neasurement, and the other one will be used to examine the anatomical path of water transport. Without moving this plant from its light environment, cut off one leaf of the pair near its axillary bud with a sharp razor, and quickly transport the cut leaf to the pressure chamber to measure the leafs water potential. Your instructor will assist in the use of the pressure chamber Note: The pressure chamber can be dangerous if not properly used. Do not use the pressure chamber unless you have been instructed in its use and fully understand these instructions. When using the chamber, al ways wear safety glasses, and never place your eye directly above the pressurized leaf chamber When you obtain the water potential value, record this value in your notebook. Next, tip the plant sideways and immerse the petiole of the remaining leaf in methylene blue solution. While the petiole is still submerged in this blue stain, cut the base of the petiole with a sharp razor. Make sure to use gloves and avoid splashing the stain on your clothes Let the petiole end of the cut leaf remain under the stain solution for one minute after the initial cut, then remove the leaf from solution and carefully blot off the excess stain solution. (With your gloves on, use a kimwipe or paper towel to do this) Quickly transfer your stained, cut leaf to a dissecting scope, and observe the cut end of the petiole. Where has the dye penetrated? Using a sharp razor blade, follow the path of dye penetration by making a longitudinal section up the petiole. Use a ruler to measure (in mm) the distance traveled by the dye, and note this value in your notebook. Repeat the entire procedure for your second plant In your notebook, prepare a table summarizing the water potential values(in MPa)and distance traveled by the dye solution(in mm) for the two treatments. Add your group's data to a class data table on the board (your instructor will assist in preparing the class table). Remember to get a copy of all class data Assignment
Procedure Students will work in teams of two. Each team will be assigned two sunflower plants, one well-watered, and one that has had water withheld, and is at or near the wilting point. Select one plant for initial measurement, and choose a pair of adjacent, well-expanded leaves near the top of the plant. One leaf will be used for water potential measurement, and the other one will be used to examine the anatomical path of water transport. Without moving this plant from its light environment, cut off one leaf of the pair near its axillary bud with a sharp razor, and quickly transport the cut leaf to the pressure chamber to measure the leaf's water potential. Your instructor will assist in the use of the pressure chamber. Note: The pressure chamber can be dangerous if not properly used. Do not use the pressure chamber unless you have been instructed in its use and fully understand these instructions. When using the chamber, always wear safety glasses, and never place your eye directly above the pressurized leaf chamber. When you obtain the water potential value, record this value in your notebook. Next, tip the plantsideways and immerse the petiole of the remaining leaf in methylene blue solution. While the petiole is still submerged in this blue stain, cut the base of the petiole with a sharp razor. Make sure to use gloves and avoid splashing the stain on your clothes. Let the petiole end of the cut leaf remain under the stain solution for one minute after the initial cut, then remove the leaf from solution and carefully blot off the excess stain solution. (With your gloves on, use a kimwipe or paper towel to do this). Quickly transfer your stained, cut leaf to a dissecting scope, and observe the cut end of the petiole. Where has the dye penetrated? Using a sharp razor blade, follow the path of dye penetration by making a longitudinal section up the petiole. Use a ruler to measure (in mm) the distance traveled by the dye, and note this value in your notebook. Repeat the entire procedure for your second plant. In your notebook, prepare a table summarizing the water potential values (in MPa) and distance traveled by the dye solution (in mm) for the two treatments. Add your group's data to a class data table on the board (your instructor will assist in preparing the class table). Remember to get a copy of all class data. Assignment: 26
A)From the class summary data, prepare a neat table summarizing the results. Your table should contain both individual team values, and average(+standard deviation values by treatment). Make sure to provide a brief descriptive legend for the table B)Prepare a bar graph summarizing the results in thetable, by treatment(average, SD or SEM). Make sure to provide a brief descriptive legend C)Turn in a short lab report(<2 pages, excluding tables and figures )that includes relevant figures and tables 6. Discussion 1. For the plants used in the experiment, how long did it take for visible signs of water stress to develop? Are there similar signs of stress in the chaparral plants? 2. Is there a correlation between dye traveled and water potential? 3. In this exercise, determination of xylem water potential with a pressure chamber requires the assumption that the pressure(tension) reading determined with the pressure chamber is a good estimate of the xylem water potential. Is this a valid assumption? 4. How do the sunflower water potentials compare to those of the chaparral plants? 5. How can chaparral plants maintain very low water potentials and still survive? 6. How could you determine if any differences are statistically significant?
A) From the class summary data, prepare a neat table summarizing the results . Your table should contain both individual team values, and average (+standard deviation) values by treatment). Make sure to provide a brief descriptive legend for the table. B) Prepare a bar graph summarizing the results in the table, by treatment (average, + SD or SEM). Make sure to provide a brief descriptive legend. C) Turn in a short lab report (< 2 pages, excluding tables and figures) that includes relevant figures and tables. 6. Discussion 1. For the plants used in the experiment, how long did it take for visible signs of water stress to develop? Are there similar signs of stress in the chaparral plants? 2. Is there a correlation between dye traveled and water potential? 3. In this exercise, determination of xylem water potential with a pressure chamber requires the assumption that the pressure (tension) reading determined with the pressure chamber is a good estimate of the xylem water potential. Is this a valid assumption? 4. How do the sunflower water potentials compare to those of the chaparral plants? 5. How can chaparral plants maintain very low water potentials and still survive? 6. How could you determine if any differences are statistically significant? 27
实验4植物的溶液培养和缺乏必需元素时的症状 【实验目的】 溶液培养和砂基培养是硏究物质营养的重要方法。本实验学习溶液培养的技术 并证明N、P、K、Ca、Mg、Fe诸元素对植物生长发育的重要性。 【实验原理】 植物须有必要的矿质元素的供应·才能保证正常的生长发育。如缺少某一元素 便表现出缺素症。把这些必要的矿质元素以适当的无机盐形式配成培养液·即能使 植物正常生长·这就是溶液培养。如把培养液加于洁净的石英砂中来培养植物·则 称为砂基培养。当培养基中缺少某种元素时就会出现营养缺乏症状·那么这种元素 被称为植物生长的“必须元素”。另外·营养缺乏症状的类型可以说明这种元素在植 物中是否是容易被调动的 【实验材料】 处于真叶期的西红柿·向日葵苗(3-5周·>30株)或者是绿豆苗(1周·>30 株)。 【设备与试剂 表4-1 (g·L-1) Ca(NQ)2.420 KNO MgSo4.7h 20 98 88 CaClz NaHco NaNo 21 EDTA - Na 745 混合即为EDTA一Fe FeSO4. 7H20 5.57 lml移液吸管丶搪瓷盘(带盖)丶250ml500m烧杯丶500~1000m量筒丶培养 缸(可用10001500m1瓷质或塑料培养缸·每组7个)、试剂瓶(500ml)pH测 试仪丶铝箔丶棉球或泡沫橡胶垫片丶塑料纱网丶5m移液吸管丶用滴瓶装的1
实验 4 植物的溶液培养和缺乏必需元素时的症状 【实验目的】 溶液培养和砂基培养是研究物质营养的重要方法。本实验学习溶液培养的技术， 并证明 N、P、K、Ca、Mg、Fe诸元素对植物生长发育的重要性。 【实验原理】 植物须有必要的矿质元素的供应，才能保证正常的生长发育。如缺少某一元素 便表现出缺素症。把这些必要的矿质元素以适当的无机盐形式配成培养液，即能使 植物正常生长，这就是溶液培养。如把培养液加于洁净的石英砂中来培养植物，则 称为砂基培养。当培养基中缺少某种元素时就会出现营养缺乏症状，那么这种元素 被称为植物生长的“必须元素”。另外，营养缺乏症状的类型可以说明这种元素在植 物中是否是容易被调动的。 【实验材料】 处于真叶期的西红柿，向日葵苗（3-5 周，>30 株）或者是绿豆苗（1 周，>30 株）。 【设备与试剂】 表 4-1 营 养 盐 Ca （NO KNO MgSO KH K CaCl NaH NaNO Na EDTA －Na FeSO 1ml移液吸管、搪瓷盘（带盖）、250ml、500ml烧杯、500～1000ml量筒、培养 缸（可用 1000～1500ml 瓷质或塑料培养缸，每组 7 个）、试剂瓶（500ml）、pH 测 试仪、铝箔、棉球或泡沫橡胶垫片、塑料纱网、5ml 移液吸管、用滴瓶装的 1 浓 度（g·L－1） 3）2·4H 2O 3 4·7H 2O 2PO 4 2SO 4 2 2PO 4 3 2SO 4 2 4·7H 2O 236 102 98 27 88 111 24 170 21 7.4 5 混合即为 EDTA－Fe 5.57
mol·L-HCl和NaOH。储备母液营养成分(见下表4.1), 分析纯药品:KNO3MgS04、KH2P4K2S4、Na2SO4NaH2PO4、NaNO3 Ca(NO3)2、CaCl2、FeSO4·7H2O、EDIA-Na2(乙二铵四乙酸二钠)。 各种大量元素及EDTA一Fe母液分别按表4-1单独配制 微量元素母液的配制:称取H3BO4286g、MnC1·4H20181 g CuSo4·5H2O 0.08gZnS04·7H200.22gH2Mc 溶于1000m蒸馏水中·即为微 量元素混合母液。 【实验步骤】 取7个培养缸·分别贴上:完全液丶缺N、缺P、缺K、缺Ca、缺Mg、缺Fe 等标签·按表4-2配制不同培养液。每处理配制的培养液倒入培养缸中使液面距缸 盖15cm为宜。选择生长一致的幼苗作实验材料·分别种在上述7种不同的培养基 中·移植时注意勿损伤根系。 4-2 每100m培养液中 贮备母液 用量(m) 全液 N K C Ag Ca(NO3)2·4H KNO 0.5 0.5 0.50.5 0.5 KH2Po 4 0.5 0.5 0.5 CaCl 0.5 NaH2po 4 NaNo 0.5 EDTA -F 0.5 0.5 0.5 0.5 微量元素 0.1 把所有的苗放入合适的培养基中后·立即用铝箔纸盖上(抑制藻类的生长) 最后把这些瓶子放在温室里·保证植株可以获得充足的阳光·使它们可以快速的生 长并表现出正确的营养缺乏症状。实验开始后每两天观察一攻·注意记录缺乏必要 元素时所表现的症状及最先出现症状的部位。用精密pH试纸检测培养液的pH 如pH高于6,应以稀盐酸调整到5~6之间。培养液每周更换一次 通过几周的观察·你将了解到在它们发育过程中不同的营养缺乏症对植物的影
mol·L-1HCl和 NaOH。储备母液营养成分（见下表 4.1）， 分析纯药品：KNO3、MgSO4、KH2PO4、K2SO4、Na2SO4、NaH2PO4、NaNO3、 Ca(NO3)2、CaCl2、Fe SO4·7H2O、EDTA－Na2（乙二铵四乙酸二钠）。 各种大量元素及 EDTA－Fe母液分别按表 4-1单独配制： 微量元素母液的配制：称取 H3BO4 2.86g 、MnC1·4H2O 1.81g 、CuSO4·5H2O 0.08g 、ZnSO4·7H2O 0.22g 、H2MOO ，溶于 1000ml蒸馏水中，即为微 量元素混合母液。 【实验步骤】 取 7个培养缸，分别贴上：完全液、缺 N、缺 P、缺 K、缺 Ca、缺 Mg、缺 Fe 等标签，按表 4-2 配制不同培养液。每处理配制的培养液倒入培养缸中使液面距缸 盖 1.5cm为宜。选择生长一致的幼苗作实验材料，分别种在上述 7种不同的培养基 中，移植时注意勿损伤根系。 表 4-2 贮备母液 Ca(NO3)2·4H KNO MgSO KH K CaCl NaH NaNO Na EDTA －Fe 微量元素 把所有的苗放入合适的培养基中后，立即用铝箔纸盖上（抑制藻类的生长）。 最后把这些瓶子放在温室里，保证植株可以获得充足的阳光，使它们可以快速的生 长并表现出正确的营养缺乏症状。实验开始后每两天观察一次，注意记录缺乏必要 元素时所表现的症状及最先出现症状的部位。用精密 pH 试纸检测培养液的 pH ， 如 pH高于 6，应以稀盐酸调整到 5～6之间。培养液每周更换一次。 通过几周的观察，你将了解到在它们发育过程中不同的营养缺乏症对植物的影 29 4·H2O 0.09g 每 100ml培养液中贮备母液的用量（ml） 完全液 2O 3 4·7H 2O 2PO 4 2SO 4 2 2PO 4 3 2SO 4 0.5 0.1 缺 N 缺 P 缺 K 缺 Ca 缺 Mg 0.5 0.5 0.5 0.5 － － － － － 0.5 0.5 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 缺 Fe － － － 0.5 0.5 － 0.5 － － 0.5 － － － － － 0.5 0.5 － － － － 0.5 － 0.1 0.5 0.5 0.5 0.5 0.5 0.5 － 0.5 0.5 0.1 － 0.5 － － － － 0.5 － 0.5 0.5 0.5 － － － － － － 0.5 0.5 0.5 － －
响。要特別注意观察叶子的色素沉积·植株的高度·叶子的数量·根的发育和其他 可见的健康指标。 作业:完成该实验总结报告。在报告的引言中要有一系列清楚的目标或这假设 对这研究的结果·结果要表现出和对照组的差异·避免模糊的表达(例如·缺氮 的植株看起来病了等表述)把观察到的结果简明扼要的总结在一个表格里·并综合 其他组的植物生长状况得出结论。在报告中要用简明的语言表达植物的生长状况 (如·高度·叶子的数量)和外观(色素沉积·缺绿病等)。建议2-3页(包括图表 和数据) 【讨论】 1.为什么说溶液培养是研究矿质营养的重要方法?根据实验结果叙番茄丶玉米 幼苗缺乏大量元素时所表现的症状并分析其原因 2.为什么要把植物置于明亮的光照下?如果把植物置于较低的光照下能得到同样 的结果吗?为什么? 3.如何利用本实验条件区分移动的元素和不可移动的元素? 4.所有的必需元素都是通过植物根尖吸收的吗?还有别的营养吸收方式吗? 5.如果糖类或者别的碳水仁合物对于植物正常生长来说是必需的·那么糖(例如 蔗糖)是不是一种很好的植物营养?怎样通过实验来验证?
响。要特别注意观察叶子的色素沉积，植株的高度，叶子的数量，根的发育和其他 可见的健康指标。 作业：完成该实验总结报告。在报告的引言中要有一系列清楚的目标或这假设 对这次研究的结果，结果要表现出和对照组的差异，避免模糊的表达（例如，缺氮 的植株看起来病了等表述）。把观察到的结果简明扼要的总结在一个表格里，并综合 其他组的植物生长状况得出结论。在报告中要用简明的语言表达植物的生长状况 （如，高度，叶子的数量）和外观（色素沉积，缺绿病等）。建议 2-3页（包括图表 和数据）。 【讨论】 1. 为什么说溶液培养是研究矿质营养的重要方法？根据实验结果叙述番茄、玉米 幼苗缺乏大量元素时所表现的症状并分析其原因。 2. 为什么要把植物置于明亮的光照下？如果把植物置于较低的光照下能得到同样 的结果吗？为什么？ 3. 如何利用本实验条件区分移动的元素和不可移动的元素？ 4. 所有的必需元素都是通过植物根尖吸收的吗？ 还有别的营养吸收方式吗？ 5. 如果糖类或者别的碳水化合物对于植物正常生长来说是必需的，那么糖（例如 蔗糖）是不是一种很好的植物营养？ 怎样通过实验来验证？ 30