The Effect of Self-, Cross-, and no Pollination on Ovule, Embryo, Seed, and Cone Development in Western Red Cedar (Thuja plicata)

1990

17 Abb., 5 Tab., 23 Lit. Ang.

Unselbständiges Werk

9716

200088535

The effects of self-, cross-, and no pollination on cone size, filled seed, pollination efficiency, ovule development, and seed efficiency were tested on rooted ramets of six western red cedar (Thuja plicata Donn) clones. To fully develop, ovules must be pollinated with viable pollen and cones must have a minimum of one developing seed. The seed potential was constant among clones and not affected by pollination. The greatest loss of potential seed resulted from a failure of ovules to be pollinated, followed closely by the low percent viability of pollen. Unpollinated ovules aborted at the megaspore or free-nuclear stages. Pollinated ovules may abort at any stage of development, but it was most common during the long free nuclear stage. Selfing had a limited effect on postzygotic loss owing to embryo abortionor on seed set. Western red cedar is well adapted for a high degree of selfing. Clonl differences occurred in seed efficiency and stages at which seed losses were most common. Seed set in western red cedar may be increased if cones on female parents having a history of high seed efficiency are pollinated several times within a 1 week peak pollination period with abundandt pollen of known high percent viability. Potential seed losses are discussed with reference to pollination and ovule development.