Stimulating dormancy release and emergence of annual ryegrass (Lolium rigidum) seeds using short-term hydrated storage in darkness
Kathryn J. Steadman A B , Gavin P. Bignell A and Pippa J. Michael AA Western Australian Herbicide Resistance Initiative, School of Plant Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
B Corresponding author; email: ksteadman@agric.uwa.edu.au
Australian Journal of Agricultural Research 55(7) 787-795 https://doi.org/10.1071/AR04010
Submitted: 19 January 2004 Accepted: 10 May 2004 Published: 2 August 2004
Abstract
Experiments were performed to determine whether the dormancy release effect of hydrated storage in darkness (dark-stratification) is common amongst annual ryegrass populations and has the potential to occur under field conditions. Dormant seeds from all populations tested (22) became sensitive to light during dark-stratification, enabling them to germinate when subsequently exposed to light. Under controlled temperature (25/15°C), light (12-h photoperiod), and hydration (solidified agar-water) conditions, more seeds germinated by 28 days if the first 14 days were in darkness followed by exposure to light for 12 h per day than if they were exposed to light throughout or darkness throughout. Constraint over the conditions imposed during dark-stratification and germination was gradually reduced to investigate whether the dormancy release effect was diminished. Dark-stratification was effective in promoting germination when performed under natural diurnal temperatures, and burial in moist soil provided suitable conditions for dark-stratification to occur. The surface of moist soil, with natural diurnal temperatures and sunlight, was suitable for germination of dark-stratified seeds. Dark-stratification is a quick and effective means to enhance the sensitivity of dormant annual ryegrass seeds to light, enabling the majority of the population to germinate. However, large quantities of light are required to promote germination of dark-stratified seeds, so buried seeds must be moved to the soil surface to allow exposure to adequate light for germination.
Additional keywords: after-ripening, dormancy loss, emergence prediction, light environment, dark-stratification, temperature, weed biology, winter annual.
Acknowledgments
WAHRI is funded by the Grains Research and Development Corporation of Australia. We gratefully acknowledge receipt of honours scholarships for PJM and GPB from the CRC for Weed Management. For seed supplies we thank David Ferris, Peter Newman, Sally Peltzer, and Vanessa Stewart (Department of Agriculture, WA), Amanda Ellery (CSIRO), and Michael Walsh (WAHRI, UWA). Mechelle Owen provided invaluable technical assistance.
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