The Similarity Between CO2 and Acid Buffer Growth Responses of Coleoptiles and Their Inhibition by Calcium
Tichenor, Lee Harris
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A study was made on the comparison between CO2-promoted elongation and acidic buffer-promoted elongation and how these growth responses could be affected by calcium. The magnitude and duration of growth response to acid buffer when osmolar inhibition is removed is 1.29 mm/segment and about 25 minutes, which are nearly the same as for a CO2 response (magnitude 1.26 mm/segment, and duration from 25 to 30 minutes). It was also shown that KCN does not inhibit the CO2 response. These results indicate that the CO2 response and acid response are the same and are both physical responses. Tests to show calcium inhibition by use of CaCl2 pretreatments showed inhibition by calcium of the acid response by increased latent period before noticeable growth rate increase (2 to 8 min.) and about a 50% reduction in the magnitude of the response. Tests to show inhibition by treatment of CaCl2 after initiation of a C02 response were inconclusive due to the osmolar effects of the CaC12 solutions. A more conclusive test of the role of calcium in elongation growth of plants is also presented.If you are not a current K College student, faculty, or staff member, email firstname.lastname@example.org to request access to this SIP.