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The influence of plant raising conditions on the head weight of crisp lettuce at maturity

Published online by Cambridge University Press:  27 March 2009

D. C. E. Wurr
Affiliation:
National Vegetable Research Station, Wellesbourne, Waruick, CV35 9EF
Jane R. Fellows
Affiliation:
National Vegetable Research Station, Wellesbourne, Waruick, CV35 9EF

Summary

Two experiments investigated the effects of raising crisp lettuce seedlings under different environmental conditions prior to transplanting, on transplant size and weight and head weight at maturity.

The use of tungsten lighting for 4 h after the end of a 12 h period of fluorescent and tungsten lighting increased transplant size and weight and the weight of heads at maturity compared with fluorescent and tungsten lighting only. Glasshouse-raised transplants were larger than those raised under artificial lighting but gave heads of similar weight to transplants which had supplementary tungsten lighting for 2 weeks. Both these treatments gave significantly heavier heads than a drilled crop or plants raised without supplementary tungsten lighting. Increasing the number of weeks of the supplementary lighting treatment tended to increase the coefficient of variation (c.v.) of head weight. Nevertheless the drilled crop had a higher c.v. of head weight than any transplanted treatment.

The variety Pennlake produced pointed (‘coned’) heads when grown in the open and its leaves were shorter and broader than those of plants grown in polyethylene tunnels, which did not show ‘coning’. It is suggested that ‘coning’ occurs primarily as a result of either lower mean temperatures or a lower amplitude of temperature when grown in the open. It occurred most frequently with glasshouse-raised plants indicating that a higher raising temperature may also contribute to the problem.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1982

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