Selection of spaced plants of perennial ryegrass in association with white clover

In conventional breeding programs of perennial ryegrass (Lolium perenne L.) spaced plants are usually evaluated on bare soil with the application of mineral nitrogen fertilizer. In organic farming, perennial ryegrass is mostly sown in association with white clover without any dressing of mineral N fertilizer. Will the selection under these organic conditions lead to varieties that are different from varieties obtained by a conventional breeding management. In 2007 we established 48 seedlings of each of 12 diploid and 9 tetraploid populations of different heading dates as spaced plants on bare soil under a conventional management with the application of 220 kg N/ha/year. 48 seedlings of each of the same populations were planted in a freshly sown stand of white clover without any N fertilizer application. Growth and crown rust infection of these plants were observed in 2008. Almost no crown rust occurred on the plants in the white clover sward. We selected plants under both managements. Although there were differences in competition and N availability the percentage of plants selected per population was nearly the same under both managements. The selected plants were put in isolated polycrosses for seed production and further progeny testing.