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  • Author or Editor: Eric E. Roos x
  • Journal of the American Society for Horticultural Science x
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Abstract

Coated and raw (uncoated) lettuce (Lactuca sativa L.) seed obtained from commercial sources were subjected to 6 storage conditions (ranging from 21° C, 90% relative humidity (RH) to 5°, 40% RH) for a period of 3 years. Four types of packaging material differing in moisture-barrier properties were used. Samples were removed periodically for moisture and germination tests. Under poor storage conditions, coated seed deteriorated more rapidly than the raw seed controls. Under favorable storage conditions, both coated and raw seed retained full viability for the 3 years.

Open Access

Abstract

Seeds of 5 cultivars of lettuce (Lactuca sativa L.) were adjusted to moisture contents between 5 and 22% and subjected to temperatures of 5, -18, -70, and -196°C (liquid nitrogen) for 7 days. Seeds with moisture contents up to 18% were not damaged by either -18 or -196°C; however, the -70°C treatment resulted in loss of germination even with seeds containing as little as 16% moisture. Seeds held at 5°C showed no loss in viability. The loss in germination at -70°C appeared to be related to cooling rate. High moisture (18 to 20%) seeds were cooled to -196°C at different rates from 1 to 200°C/min. Germination was reduced in seeds cooled at rates slower than 25°C/min. At 200°C/min cooling rate and 18 to 20% seed moisture both germination and root growth occurred although at reduced levels compared with control seeds held at 5°C. Prolonged storage (33 days) in liquid nitrogen of rapidly frozen high moisture lettuce seeds did not result in further loss of germination after the initial freezing to -196°C.

Open Access