Articles containing the keyword 'rest period'

Models concerning the effects of temperature on dormancy release in woody plants were tested using two-year old seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.). Chilling experiments suggest that the rest period has a distinct end point. Before the attainment of this end point high temperatures do not promote bud development towards dormancy release, and after it further chilling does not affect the subsequent bud development. A new hypothesis of dormancy release is suggested on the basis of a comparison between present and earlier findings. No difference in the proportion of growth commencing seedlings were detected between the forcing temperatures of 17°C and 22°C. The rest break of 50% of Norway spruce and Scots pine seedlings required six and eight weeks of chilling, respectively. Great variation in the chilling requirement was found, especially for Scots pine.

The PDF includes an abstract in Finnish.

• Hänninen, E-mail: hh@mm.unknown
• Pelkonen, E-mail: pp@mm.unknown

Logical structure of three simulation models and one conceptual model concerning effects of temperature on dormancy release in woody plants was examined. The three basic types of simulation models differed in their underlying assumptions. Contrasting implications of the models were inferred by deduction. With the aid of these implications, the model types can be tested using experiments with continuous and interrupted chilling. Similarly, implications of the conceptual model of rest phases were inferred, by which the model can be tested using experiments with continuous chilling and forcing in multiple temperatures. The possibilities to synthetize the conceptual model with any of the three simulation model types, as well as the biological interpretation of the model variables, were discussed.

The PDF includes an abstract in Finnish.

• Hänninen, E-mail: hh@mm.unknown