Outcrossing Rates in Barley Populations in the Canadian Prairies

Abstract

Using three morphological markers, the magnitude of natural cross-fertilization in three successive generations, F,, P;, and F, of foul single crosses of barley (Hordeum vulgare L.) was estimated under dryland conditions of the Canadian Prairies. The average frequency of outcrossing was very low (0.35%). Somewhat higher rates of outcrossing were observed in a highly variable composite cross population of barley (CC XXI). CC XXI showed an overall outcrossing rate of 0.8096, when propagated under irrigated conditions, but only 0.47% under rainfed conditions. Outcrossing was significantly influenced by three eomponents of the environment: temperature, precipitation and relative humidity during the flowering period. Temperature was most important when moisture was not limiting, whereas precipitation wae the most important factor under field level drought. The overall frequency of outcrossing in CC XXI was not only considerably lower in the Prairies than in California or Scotland, but decreased progressively with advancing generations, in contrast to results in California.Au moyen de trois marqueurs morphologiques, on a pu estimer dans les conditions normales dts Prairies l'amplitude de l'exogamie naturelle dms trois ginirations successives (F,, F4 et %) chez quatre croisements simples d'orge (Hordeum vulgare L.). La friquence moyenne d'kxogamie s'est averke trks faible (0.35%). Des taux quelque peu plus ilevis furent obsemis dans une population croide t&s variable (CCXXI). Ainsi, la ligntk CCXXI affkkait un taux global d'ixogamie de 0.8Q8, sous irrigation, en regard de 0.47%, sans a p r t d'eau. L'ixoglarnie itait influencie de fason significative par trois composantes de I'environnement: la tempkrature, la precipitation et l'humidit6 relative au cours de la M o d e de floraison. La tern+rature ttait plus importante lorsque l'humidit6 n'6tait pas un facbur limitatif, alors que la prkcipitation s'avbait le facteur le plus important dans les conditions de s6cheresse. La Mquence globale d'ixogamie chez CCXXI n'itait pas searlement plus faible dans les Prairies qu'en Californie ou en Ecosse, mais dicroissait graduellement au fur et P mesure des generations, contrairement aux r&ultats obtenus en Cdifornie.[Traduit par le journal]

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

“…In addition, under cool and moist conditions, higher outcrossing rates may be caused by extended pollen viability (Hammer 1977;Lansac et al 1994;Gupta et al 2000). Our results agree with the findings of Giles et al (1974), Brown et al (1978) and Chaudhary et al (1980) who showed that cool and moist conditions promote outcrossing in barley.…”

“…In any case, the discrepancy between the t m and t e estimates indicates considerable annual fluctuations of the outcrossing rate. Similar observations have been reported for barley populations under dry conditions in the Canadian Prairies (Chaudhary 1980) as well as in other self-fertilized species such as Phaseolus lunatus (Allard and Workman 1963), Avena fatua (Imam and Allard 1965) and in allogamous but self-fertile rye materials (Geiger and Schnell 1970).…”

“…Chaudhary et al (1980) reported a low average outcrossing rate in barley (0.35%) grown under the dry-land conditions of the Canadian prairies. Some authors have obtained slightly higher estimates than those reported in the present study.…”

“…High rainfall and cool environmental conditions can promote outcrossing in barley (Brown et al 1978;Chaudhary 1980). Parzies et al (2000) reported higher outcrossing rates under fluctuating rainfall conditions.…”

Estimation of Quantitative Genetic Parameters for Outcrossing-Related Traits in Barley

“…spontaneum K. Koch in the Near East. Therefore, barley is considered as a self‐pollinator with a high degree of cleistogamy (Giles et al, 1974; Brown et al, 1978; Chaudhary et al, 1980; Doll, 1987; Parzies et al, 2000). Yet, variation has been observed for spikelet opening and anther extrusion at anthesis (Virmani and Athwal, 1973; Ceccarelli, 1978; Doll, 1987; Hammer, 1984; Gupta et al, 2000; Abdel‐Ghani et al, 2003).…”