Germination of serotinous cone seeds in Cupressus ssp.

Abstract

Cone serotiny refers to canopy seed storage in cones that remain alive, though closed, for several years. There are some Cupressus species which have only serotinous cones, or both serotinous and non-serotinous cones on the same tree. Scale separation and seed release occurs immediately after the cone ripens in non-serotinous cones, or else the cones remain closed and alive longer, generally up to 15-20 years. Germination tests were done with serotinous cone seeds from C. arizonica Greene, C. benthamii Endl., C. lusitanica Mill., and C. macrocarpa Hartw. Germination was below 50% for all species. The highest levels of germination were obtained from 2- to 7-year-old cones, depending on the species. Cupressus arizonica showed a regular decline in germination values, from 43.5% for seeds from 3-year-old cones to 7.5% for seeds from 7-year-old cones. Cupressus benthamii had a maximum germination value of seeds from 5-year-old cones. Cupressus macrocarpa had a maximum germination capacity of 20.5% for seeds from 6-year-old cones, and it showed 7.5% germination for 12-year-old seeds. Cupressus lusitanica reached 33.5% germination of seeds from 5-year-old cones. Serotinous cones from Cupressus species, usually not collected because it is assumed that their seeds are not viable, can be utilized in cone harvesting, increasing the yield of the cone-bearing trees.