Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 19, 2003
Publication Date: February 11, 2004
Citation: Clements, D.D., Young, J.A., Harmon, D.N. 2004. Germination ecology of seeds of centaurea sulphurea [abstract]. Weed Science Society of America Meeting Abstracts. 44:37. Technical Abstract: Sicilian starthistle (Centaurea sulphurea Willd.) is one of the rarer species of Centaurea introduced to North America. It is restricted to relatively small patches in California. It is a noxious weed in California and hopefully it can be suppressed because the phyllaries (bracts) that subtend the flower heads are armed with stout spines 25 to 35 mm long. Among the Centaurea introduced to North America, Sicilian starthistle is unique in having quite large achenes (seeds) with a persistent long pappus. We compared the germination of seeds of Sicilian starthistle at 55 constant or alternating temperatures ranging from 0 through 40C. The seeds had some germination at over 80% of the temperature regimes tested. For a species native to southern and south eastern Europe, the seeds had very high germination at very cold and cold seedbed temperatures and much lower germination at warm fluctuating or warm incubation temperatures, At moderate temperatures, germination averaged 90%. Optimum germination, defined at not lower than the maximum observed minus one half the confidence interval at the 0.05 level of probability, occurred at extremes in temperature from 0/2C (0 C for 16 hours and 2 C for 8 hours in each 24 hour period) to 25/30 C. Germination at these extremes was 100%. The germination of Sicilian starthistle compares favorably to that obtain using the same experimental procedure with seeds of Centaurea solstitialis L.