Alleviation of Thermodormancy in Coated Lettuce Seeds by Seed Priming

in HortScience
Authors:
Veronica M. ValdesDepartment of Vegetable Crops, University of California, Davis, CA 95616

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Kent J. BradfordDepartment of Vegetable Crops, University of California, Davis, CA 95616

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Keith S. MayberryDepartment of Vegetable Crops, University of California, Davis, CA 95616

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Abstract

Lettuce (Lactuca sativa L. ‘Empire’) seeds (achenes) were given an osmotic priming treatment (24 hr in aerated —1.5 MPa polyethylene glycol (PEG 8000) solution at 18°C in the light) which alleviated thermodormancy in laboratory tests. The seeds then were coated commercially for precision planting. Additional seeds also received a proprietary treatment for enhancing high temperature germination (Royal Sluis Split-kote D). In field trials in the Imperial Valley of California, where the soil temperature exceeded 35°C for the first 11 hr of imbibition under sprinkler irrigation, total emergence of untreated seeds after 6 days was between 18% and 21%, whereas that of primed and Splitkote D seeds ranged from 46% to 69%. Uniformity and rate of emergence were also greater for the primed seeds, with 91 % of the final emergence occurring by the 3rd day, as compared to only 70% for the control. Seed priming prior to coating can be an effective method of improving lettuce stand establishment under high temperature conditions.

Contributor Notes

Graduate Research Assistant. Present address: Las Nieves 3343, Santiago 10, Chile.

Assistant Professor. To whom reprint requests should be addressed.

Farm Advisor, Imperial County, 939 Main Street, El Centro, CA 92243.

Received for publication 29 Oct. 1984. This research was supported in part by a grant from the California Iceberg Lettuce Research Board to KJB and a scholarship from the Organization of American States to VMV. Moran Seeds, Inc., provided seeds and Royal Sluis, Inc., provided seeds and coated the experimental lots. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.

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