Seed Dormancy and Factors Controlling Dormancy Breakdown in Buffel Grass Accession from Contrasting Provenances

Publisher Website
Google Scholar
Abstract
(1) Seed dormancy and factors affecting dormancy breakdown were studied in fifteen accessions of buffel grass (Cenchrus ciliaris), eight of near-equatorial and six of near-tropical origin, plus cv. Biloela. Within latitudes of origin, pairs of accessions were from high (1200-1400 mm), medium (700-850 mm), low (400-500) and very low rainfall (25-200 mm) sites. (2) Plants were grown in SE Queensland. Ripe fascicles were subjected to a range of temperature and stratification treatments and germination, dormancy and viability were recorded. (3) Four weeks after harvest, percentage germination was 0-5.5%, and the percentage of dead seeds was 0-18.5% (with an anomalous 34.6% for one accession). (4) Treatment of fascicles 4 weeks after harvest at 60.degree.C or alternating 60/25.degree.C for 12 weeks significantly increased germination. Germination was higher from equatorial than from near-tropical accessions and from high than from low rainfall provenances. (5) Treatment of either dry or moistened fascicles at 4.degree.C for 2-8 weeks had little effect on dormancy, but moistening reduced viability. (6) The percentage of dead seeds tended to be lower in equatorial and higher rainfall accessions. High temperature decreased viability, but after 2 weeks of treatment the rate of loss of viability was similar in high and low temperature treatments. (7) Seeds from fascicles with more than one seed were more dormant than those from one-seeded fascicles and had lower germination percentages. (8) Maximum percentage germination for an accession was related to the percentage of living seed shortly after harvest, which confounded interpretation of data in terms of dormancy differences. (9) It is concluded that buffel grass accessions differ in dormancy attributes which may be adaptive to their climate of origin.