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. 2015 Mar 3;6:120. doi: 10.3389/fpls.2015.00120

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Copyright © 2015 Harrington and Gould.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Pictures taken in August 2013 of seedlings receiving a range of chilling and forcing hours during the 2012–2013 fall-winter-spring seasons. The colored flags indicate four temperature treatments from warmest (left) to coolest (right): yellow flag, Warm (in greenhouse continuously); red flag, Warm plus Cool Interruption, (greenhouse with 1 day/week outdoors); blue flag, Ambient plus Warm1 (outdoors with 1 day/week in greenhouse), and white flag, Ambient (outdoor conditions only). Shown from top to bottom are: (A) lodgepole pine, (B) grand fir, and (C) Pacific madrone.