ifoam'96 Book of Abstracts 11th IFOAM Scientific Conference 11-15 August 1996, Copenhagen, Denmark

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Response of Vegetable Varieties. P1; 22

Fachhochschule Nürtingen, D-72622 Nürtingen, Germany

Results of experiments performed in cooperation with the Bundes sortenamt (BSA), and financially supported by the German Ministry of Agriculture. The objective of the experiments has been to test yield and quality of varieties of vegetables under conditions of organic agriculture, to recognize reciprocal effects of varieties and cultivation systems and to proof the value of the listing of variety characteristics of the »Beschreibende Sortenliste« with respect to organic horticulture. Accordingly we tested 5 different species, namely lettuce (Lactuca sativa), white cabbage (Brassica oleracea var. capitata), carrot (Daucus carota), leek (Allium porrum) and celeriac (Apium graveolens var. rapaceum). We used 5 varieties each, some of which were bred for or maintained in organic horticultural systems. All varieties were tested on organic farms for three years at three different sites. Simultaneously they underwent the regular BSA testing procedure.
Results of the experiments: Most of the species and varieties yielded less when cultivated organically except for white cabbage. The percentage of marketable vegetables was identical in both systems. Yield differences between varieties became significantly apparent when cultivated conventionally. Varieties bred or maintained in organic systems showed no differences while cultivated organically. Except for carrot they yielded less cultivated conventionally. Varieties grown organically showed significant better external quality at all sites and years. Again there had been more significant differences between varieties grown conventionally. Cabbage, leek and celeriac showed reciprocal effects between varieties and cultivation system. Varieties maintained or bred in organic systems ended up with varying reactions. E. g. »Ortho« a celeriac variety bred organically was best in external quality under both cultivation systems whereas the carrot variety »Lange rote stumpfe ohne Herz 6« represented the average of the carrot varieties under both systems.
Organically grown lettuce and carrot showed a significantly low content of nitrate. Carrots showed comparable contents of sugar under both systems but less carotin organically grown. As to celeriac, »Ortho« showed significantly poorer inner quality under both systems.
The listing of the »Beschreibende Sortenliste« turned out to be of limited value at least for some varieties and/or characteristics under organic production.
Because both species and varieties do not react uniformly to cultivation systems we recommend to test new varieties in particular in an organic cultivation system.