Growth, morphology, and cold hardiness of Chamaecyparis nootkatensis seedlings originating from an abbreviated reproductive cycle

Abstract

A common garden study investigated growth, morphology, and cold hardiness of yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) seedlings originating from seed that had matured at an accelerated rate. This early maturing seed, produced at a low-elevation southern Vancouver Island seed orchard, was known to have similar germinability and seedling morphology as high-elevation normally maturing seeds. Population differences in 3-year-old seedlings were evident only in shoot harvest index (ratio of stem/shoot dry weight). The amount of stem elongation that occurred prior to the formation of secondary foliage (juvenile height) and harvest index were weakly correlated with source elevation at which maternal parents were developed. Traits that exhibited no discernable differences between progeny from early maturing seed and the control normally maturing seed included midwinter cold hardiness testing and selected measures of shoot morphology and growth. The control seedlings had significantly less height growth prior to the transition of primary foliage to secondary foliage formation than did the seedlings originating from early maturing seed.