Does regional organic screening and breeding make sense? Experimental evidence from organic outdoor tomato breeding

Summary

Does regional organic screening and breeding make sense? To answer this question we looked for experimental evidence in an organic outdoor tomato project. Potentially suitable varieties were collected, genotype x environment interactions were investiga-ted and selection was carried out within three crosses at three farms in Central and Northern Germany. The resulting selections were compared at all farms. Screening within organic horticulture was the most important means of finding suitable varieties. After three years of evaluation, 71% of the 18 most successful varieties came from colleagues within organic horticulture. The analysis of the regional evaluation did not reveal strong interactions of varieties and locations. The rate of Phytophthora (late blight) fruit infections significantly depended on the year, thus stressing the need for long-term evaluation. Site specific adaptation was partially observed for late blight in-fections and for yield. The main advantage of multilocational selection, however, was to make use of the selection potential at each farm. At Rhauderfehn, the farm with the highest level of Phytophthora infections, selection led to reduced fruit infection and extended harvest period. Selection at Ellingerode resulted in the highest yield. We recommend multilocational breeding approaches with frequent exchange of breeding material and data.