Chilling Units or Chilling Hours
Chilling unit in agriculture is a metric of a plant's exposure to chilling temperatures. Chilling temperatures extend from freezing point to, depending on the model, 45 °F (7 °C) or even 60 °F (16 °C). Stone fruit trees and certain other plants of temperate climate develop next year's buds in the summer. In the autumn the buds go dormant, and the switch to proper, healthy dormancy is triggered by a certain minimum exposure to chilling temperatures. Lack of such exposure results in delayed and substandard foliation, flowering and fruiting. One chilling unit, in the simplest models, is equal to one hour's exposure to the chilling temperature; these units are summed up for a whole season. Advanced models assign different weights to different temperature bands.
Read more about this topic: Chilling Requirement
Famous quotes containing the words chilling, units and/or hours:
“I swear to keep the dead upon my mind,/Disdain for all time to be overglad./Among spring flowers, under summer trees./By chilling autumn waters, in the frosts/Of supercilious winter—all my days/I’ll have as mentors those reproving ghosts.”
—Gwendolyn Brooks (b. 1917)
“Even in harmonious families there is this double life: the group life, which is the one we can observe in our neighbour’s household, and, underneath, another—secret and passionate and intense—which is the real life that stamps the faces and gives character to the voices of our friends. Always in his mind each member of these social units is escaping, running away, trying to break the net which circumstances and his own affections have woven about him.”
—Willa Cather (1873–1947)
“I sometimes left a good fire when I went to take a walk in a winter afternoon; and when I returned, three or four hours afterward, it would be still alive and glowing. My house was not empty though I was gone. It was as if I had left a cheerful housekeeper behind. It was I and Fire that lived there; and commonly my housekeeper proved trustworthy.”
—Henry David Thoreau (1817–1862)