The effect of fluid sowing pre-germinated seed of crisp lettuce on emergence and maturity characteristics

Abstract

Supermarkets in the U.K. want uniform heads of crisp lettuce weighing at least 450 g and preferably 600 g but it is difficult to meet these requirements consistently throughout the season because there can be considerable variation in head weight both between and within sowings. In the butterhead lettuce crop the synchronization of seedling emergence, which was responsible for a large proportion of the variation in head weight at maturity (Gray, 1976), was improved by fluid sowing pre-germinated seed (Gray, 1978a, 6). Finch-Savage & Cox (1983) have also shown with butterhead lettuce that pre-germinated seed emerged earlier and produced earlier-maturing, heavier heads than dry seed and that the addition of sodium phosphate to the gel further advanced maturity and increased head weight. Therefore, fluid sowing pre-germinated seed of crisp lettuce in a gel containing phosphate might be expected to reduce variation in seedling emergence and to improve head weight and the uniformity of head weight at maturity.