Physical characteristics measured individually for each lettuce (Lactuca sativa L.) seed and its embryo were significantly correlated with seedling and plant growth (vigor) up to a certain stage, possibly heading, after which the correlations diminished. Embryo physical measurements, although slightly better correlated with subsequent vigor than seed (achene) physical measurements, were highly correlated with those of the whole seed.
Of the 5 physical measurements studied, all but length were found to be associated with early vigor. Thorough statistical analyses place seed and embryo physical characteristics in a consistent and significant order in determining vigor: weight > thickness > density (as measured by an air column) > width > length.
Received for publication October 11, 1973. This research was supported in part by a grant-in-aid from the California/Arizona Lettuce Research Corporation. Technical assistance of J. Moore and statistical analysis by C. Adams are gratefully acknowledged. This report is to be submitted as partial requirement for the Ph.D. by the senior author.
Present address: Kibbutz Ein-Gedi, Israel.
Department of Plant Sciences.