FRST 303 Lecture 19: November 18, 2014.docx
Document Summary
Last day: frost hardiness and bud dormancy, 2 stages induced by a) short days followed by b) low temp two ways of becoming frost hardy, gymnosperms cells lose water to avoid freezing damage, deciduous tress just drop their leaves but first recycle nutrients, and undergo color change, growth resumption anthocyanins (red), caretenes (orange) and antioxidants, 2 safeguards to ensure the seedling doesn"t start growing too early (when there is a chance of damaging or killing frost) chilling requirement cumulative heat sum counts the number of degree days, activation temp of about 5 degrees so counts number of days above 5 degrees, leaf primordial begin to mature into leaves, determinate leaf growth trees have a quick growth of the leader (the main stem that grows straight up, indeterminate grows more slowly because it is determining amount of growth as it goes, they are growing the same amount though, just a difference in time, apical dominance.
