BEHAVIOUR OF SOME LETTUCE COMPONENTS GROWN ON SOIL DISINFESTED WITH METHYL BROMIDE

Experiments dealing with lettuce components influenced by soil disinfestation with methyl bromide were done with two current soil compositions (sandy loam and organically enriched sandy loam), three lettuce cultivars (cvs. ‘Suzan’, ‘Zwaresse’, ‘Deci-Minor’) and three doses methyl bromide (90 g/m² for the first experiment, 50 and 100 g/m² for the second experiment). For both cultures, analyses were effectuated on young crops and on nearly full-grown lettuce heads.
The following criteria were studied : plant weight, dry material and ash contents, total bromide content, potassium and nitrate.
Manganese was estimated for the second culture only.
Organic constituents studied were : glucose, fructose, sucrose, pectin and wax.
From both experiments it could be concluded that there was a rather strong increase of plant weight when grown on disinfested soil and the same samples showed lower dry matter and ash content.
Bromide contents were very high and dosage dependent.
Potassium and nitrate contents increased to a considerable extent.
Increased manganese content did occur only in the last growing stage.
Glucose, fructose and sucrose contents of more developed lettuce plants showed a decrease in samples originating from the fumigated plots.
Pectin and wax contents were not related to methyl bromide treatment.
Nitrate content needs some further investigation because of the important raise after methyl bromide application.
Only little importance was accorded to soil type and cultivar and therefore a choice of other cultivars has not yet been suggested.

Symposium on Quality of Vegetables

E. Van Wambeke, A. Vanachter, E. De Winter, C. Van Assche

https://doi.org/10.17660/ActaHortic.1979.93.23