{"id":218,"date":"2018-06-08T22:47:28","date_gmt":"2018-06-08T22:47:28","guid":{"rendered":"http:\/\/sites.warnercnr.colostate.edu\/ocheltw\/?page_id=218"},"modified":"2018-06-27T20:18:45","modified_gmt":"2018-06-27T20:18:45","slug":"510-assignment-4","status":"publish","type":"page","link":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/f-510\/f510-assignment-descriptions\/510-assignment-4\/","title":{"rendered":"510 Assignment #4"},"content":{"rendered":"

[vc_row][vc_column][vc_column_text]<\/p>\n

F510<\/strong><\/h3>\n

Activity #4<\/strong><\/h3>\n

Leaf Water Potential Activity<\/strong><\/h3>\n

 <\/p>\n

Introduction<\/strong><\/h4>\n

Today we will be measuring and evaluating the leaf water potential of some different plants.\u00a0 Water potential is the measure of total free energy of a solution, and the results are presented relative to pure water at a standard temperature and pressure.\u00a0 In plants, water typically has less free energy than pure water because of the presence of solutes (think simple sugars) and the tension water is under as it is being extracted from the soil.\u00a0 Therefore (and unfortunately) we are going to be dealing with negative numbers, which are always a bit counter-intuitive.\u00a0 The lower the free energy of water in the leaf, the more difficult it is for the plants to maintain hydration.\u00a0 Therefore, the lower the leaf water potential, the more water \u2018stressed\u2019 the leaf often is, although there are exceptions to this we will discuss throughout the course.<\/p>\n

Now, the leaf water potential is a function of two main processes: 1) the osmotic potential (or osmotic concentration) and 2) the turgor pressure.\u00a0 Turgor pressure is the pressure that cell membranes exert on the contents of the cell. A water balloon is a good analogy; when you fill up a balloon with water, as the balloon begins to stretch under the pressure of the water inside, the material of the balloon also exerts a force back on the water inside the balloon.\u00a0 Turgor pressure increases the free energy of the water and has positive values.\u00a0 The concentration of solutes in cells interact with water molecules and reduce the free energy of the solution; the more solutes the lower the free energy and the lower the osmotic potential \u2013 resulting in negative values. The balance of turgor pressure and osmotic potential result in the water potential of a leaf. There is a third force that can play a role in leaf water potential, but we\u2019ll talk about this more in lecture.\u00a0 But for now, we\u2019ll assume that leaf water potential equals:<\/p>\n

 <\/p>\n

Yleaf<\/sub> = Yosm<\/sub> + Yturgor<\/sub><\/p>\n

\u00a0<\/sub><\/p>\n

During lab today we will measure Yleaf<\/sub> and Yosm<\/sub>, allowing us to estimate Yturgor<\/sub>.<\/p>\n

 <\/p>\n

Objective<\/strong><\/h4>\n

The objective of this activity is to give students hands-on experience measurement leaf water potential and its constituent parts.\u00a0 In addition, students will learn to interpret the results of leaf water potential as it pertains to water stress in plants.\u00a0 Finally, we will compare the data we collect in lab to similar data reported in the literature during a class discussion.<\/p>\n

 <\/p>\n

Instructions<\/strong><\/h4>\n
    \n
  1. Measure leaf water potential of a species and record its value in the table below. Share your data with other groups so that we can compare among different species and functional groups.\u00a0 We will go over the methods for estimating leaf water potential during lab.<\/em><\/li>\n<\/ol>\n

    [\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”221″ img_size=”large”][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]2. Measure the osmotic potential of a leaf and record its value below. Note:<\/em> There is a video on my lab\u2019s YouTube channel that you can use for reference.<\/em>[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”222″ img_size=”large”][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]3. Calculate the turgor pressure of the leaf you measured and record its value below. And then share your data with other groups so that we can look at interspecific and functional group differences in lecture.[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”223″ img_size=”large”][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]Bring your data with you to our next class and we will discuss our results as a group and we will compare that data we collected with the articles you are reading for our next literature discussion.[\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

    [vc_row][vc_column][vc_column_text] F510 Activity #4 Leaf Water Potential Activity   Introduction Today we will be measuring and evaluating the leaf water potential of some different plants.\u00a0 Water potential is the measure of total free energy of a solution, and the results are presented relative to pure water at a standard temperature and pressure.\u00a0 In plants, water […]<\/p>\n","protected":false},"author":109,"featured_media":0,"parent":266,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-218","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/pages\/218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/users\/109"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/comments?post=218"}],"version-history":[{"count":4,"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/pages\/218\/revisions"}],"predecessor-version":[{"id":226,"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/pages\/218\/revisions\/226"}],"up":[{"embeddable":true,"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/pages\/266"}],"wp:attachment":[{"href":"https:\/\/sites.warnercnr.colostate.edu\/ocheltw\/wp-json\/wp\/v2\/media?parent=218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}