Leaf Abscission

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Hormone Control of Leaf Abscission Lab Report
February 24, 2011
By Patrick Mills

Introduction-
Hormones are a chemical are transported within an organism and are highly specific chemical signals between cells. The hormones we used were lanolin, auxins(IAA), cytokinins(CYT), ethylene(ETH), and gibberellins(GA) and each has a different purpose. Auxins will control cell elongation, cytokinins promote the act of cell division, ethylene causes the ripening of fruit, and gibberellins will elongate plant stems. “Leaf abscission or the loss of leaves is controlled by two different modes of hormone activity: one to suppress abscission activity and the other to stimulate it” (Mcfarland 1995, 42), and IAA is produce naturally in the leaf blade and prohibits leaf abscission. An example of this is when leafs fall in autumn and fruit falls when it is ripe. The objective of the experiment is to see the effect the hormones will have on the leaf petiole. If applying different hormones (Lanolin, IAA, CYT, ETH, GA) to a leaf petiole will provide stimulation, then the different hormones will help the petioles stay alive to the end of the seven day period. Methods-

* We obtained 7 coleus plants, three will be controls and four will be hormone treated plants. * For each of the hormones we treated a select two leaves on opposite position on the stem. * We took a razor blade and cut selected leaf blade off at the top of the petiole. * We applied Lanolin (Plant 3) enough to seal off the end of the cut petiole, make sure to use different applicator for each plant. * We repeat this step for each hormone treatment (Plants 4-7). * We tied Dental Floss around the petiole and stem to be able to tell if one fell * To identify different plants we color coordinated them with seven different colored yarn. * For the next seven days we observed the plants to see the change that occurred. Results-

The graph above shows our group data that we collected...
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