The effect of self-, cross-, and no pollination on ovule, embryo, seed, and cone development in western red cedar (Thujaplicata)

Abstract

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 (Thujaplicata 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 abortion or on seed set. Western red cedar is well adapted for a high degree of selfing. Clonal differences occurred in seed efficiency and stages at wich seed losses were most commun. 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 abundant pollen of known high percent viability. Potential seed losses are discussed with reference to pollination and ovule development.

Determination of Genetic Variation Between Populations of Abies nordmanniana subsp. bornmulleriana Mattf According to Some Seed Characteristics

“…Several factors affect the production of high quality seeds, such as insect infestation (El Atta 1993, Dajoz 2000, Bates et al 2000, pollination failure and post-zygotic degeneration (Owens et al 1990, El-Kassaby et al 1993, infection by seed borne pathogens (Pritam and Singh 1997), environmental conditions during seed development (Gutterman 2000) as well as the genetic constitution (Bazzaz et al 2000).…”

Fine-scale estimation of outcrossing in western redcedar with microsatellite assay of bulked DNA

“…The outcrossing rate for most conifer species is above 80% (52 species, mean 83.5%; reviewed in O'Connell, 2003). While western redcedar produces abundant viable selfed seeds (Owens et al, 1990), inbred trees produced by self-fertilization have shown significant reduction in growth rate (ca. 10%) compared to noninbred trees (Russell et al, 2003).…”

Microcomputer tomography (microCT) as a tool in Pinus tree breeding: pilot studies

“…The number of seed harvested is generally considered an indication of breeding success (Johnsson 1976). However, pre-zygotic barriers (before fertilisation) can reduce the numbers of mature cones or seed harvested, while post-zygotic barriers (after fertilisation) can increase the number of hollow seeds without affecting the number of seed extracted from the cones (Critchfield and Kinloch 1986;Owens et al 1990). Therefore, estimating the time (in weeks) after pollination that fertilisation might occur can help to estimate viable seed set during interspecific hybridisation and make subsequent tissue-culture (embryo rescue and micropropagation) projects more effective (Cisneros and Tel-Zur 2010).…”

“…Although pollination and fertilisation in Pinus species may yield a large number of mature cones filled with seed, some might be non-viable due to pollination failure or post-zygotic degeneration (Owens et al 1990;El-Kassaby et al 1993). Seeds need to be extracted, and viable seeds separated from non-viable ones (Bramlett et al 1977) before sowing.…”