Changes in mitotic index during onset of dormancy in Douglas-fir seedlings.

A method is presented for rapid determination of the mitotic index in terminal buds of Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco. Fertilization at planting increased mitotic index but fertilized seedlings entered dormancy at the same time as unfertilized seedlings. Cold storage, prior to dormancy, reduced mitotic index rapidly and was related to reduced height growth the following year. The effects of moderate moisture stress and seed source on mitotic index were slight.