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Title: Temperature and moisture status affect afterripening of leafy spurge (Euphorbia esula) seeds

Author
item Foley, Michael

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 3/1/2008
Citation: Foley, M.E. 2008. Temperature and moisture status affect afterripening of leafy spurge (Euphorbia esula)seeds. Weed Science. 56:237-243.

Interpretive Summary: Although seed dormancy is a key characteristic of weedy plants, mechanisms governing seed dormancy are unknown. To begin to understand seed dormancy in leafy spurge, we determine whether population, time, temperature, and seed moisture content interact to regulate afterripening, which is the transition from a dormant to less or non-dormant state. Temperature and seed moisture content are the primary factors that regulate afterripening.

Technical Abstract: Increasing the germination potential of dormant seeds in a population over time generally requires afterripening. Research was conducted to study the relationship between temperature and seed moisture content on afterripening of dormant leafy spurge seeds. Germination of non-afterripened seeds was 59% and 36% after 21 d for the Harwood and Fargo populations, respectively. Germination of 85 to 87% and 58 to 62% was obtained for the Harwood and Fargo populations, respectively when afterripened for 12 to 24 wk under the optimum conditions of 30 C and 2.5% seed moisture; increasing the temperature to 45 C did not increase afterripening. Afterripening decreased slightly at 30 C as the seed moisture content increased to 5.6%, but germination still exceeded that of non-afterripened seeds. Afterripening at 30 C with a seed moisture content of '9% greatly decreased germinability due to seed ageing. A temperature of 5 C was effective for afterripening when the moisture content was 3.3%, but germination was still slightly less than for the low moisture content seeds afterripened at 30 C. Afterripening seeds with 6 to 13% moisture at 5 C generally provided little improvement in germination compared with the control, but did not result in seed ageing.