Importance of Collard and Kale Genotype for Winter Production in Southeastern United States

Abstract

Winter production of collard and kale (Brassica oleracea L. Acephala Group) in the southeastern United States is limited by the tendency of these leafy green vegetables to bolt following vernalization. Collard and kale cultivars, landraces, and breeding lines were tested in four winter environments from 1992 to 1995 to determine differences among all included entries for winter production and tendency to bolt in a cold season environment. Essentially all entries survived the conditions of four winter environments. However, whether an entry reached harvest size depended on its date of 50% bolting. Collard typically bolted earlier than kale. Most kale entries reached a marketable size before bolting, while only the collard cultivars `Blue Max' and `Champion' and landraces G. Summersett and Mesic Zero consistently did the same. Several entries, for example, `Squire' kale and G. Summersett collard, usually did not bolt. Results of this research indicate that significant genetic control of the long-standing (delayed bolting) phenotype is present in collard and kale. Successful winter production of these cole crops can be better ensured by using a long-standing genotype.