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.