Strategy for catch crop development .1. Hypothetical ideotype and screening of species

Hypothetical criteria were defined for a catch crop insown in spring cereals with the main purpose of reducing leaching of nitrogen. The criteria were applied in the screening of a large variable plant material from three groups: Poaceae, Fabaceae and species from other families. Variation in the characters of interest between and within species was recorded in spaced field plantings. Perennial species adapted to the Nordic climate possessed many of the characteristics expected to be desirable. Accessions expected to have a potential as catch crops were identified in all three groups. The group ''other families'' is of great interest. The most interesting species for further experiments were Cichorium intybus, biennial species in Brassicaceae, Lotus corniculatus, Trifolium fragiferum and Lolium spp.