VERNALIZATION REQUIREMENT OF WINTER AND SPRING OAT GENOTYPES

Unfavorable weather conditions often make it desirable to plant oat (Avena sativa L.) in the spring in areas where winter oat cultivars are usually planted. Information regarding vernalization requirements is needed to determine whether winter or spring oat cultivars should be planted. Twenty-five winter and rive spring oat genotypes were evaluated for responsiveness to vernalization. Germinated seeds were vernalized at 5-degrees-C and a 12-h photoperiod for 0, 12, 24, or 48 d. Seedlings were transplanted to a greenhouse with an 18-h photoperiod and temperature of 21-degrees-C day/18-degrees-C night. All winter oat genotypes responded to cold treatment with a decrease in days to heading, whereas none of the spring oat cultivars responded to vernalization for days to heading. Although there was variability among three plantings of the experiment, 24 d of vernalization was sufficient to fully vernalize all winter genotypes. The length of time required for panicle emergence for the winter oat genotypes was reduced by the 24-d cold treatment an average of 19 d compared with the nonvernalized controls. The cultivars Dubois and Madison were the most responsive to vernalization, showing an average decrease of 52 and 45 d to heading, respectively, after 24 d of cold treatment in three experiments. Vernalization reduced plant height in many of the winter oat genotypes. Dubois and Madison were the only genotypes that consistently increased in plant height in response to vernalization. There were no differences in any of the measured variables between the 48- and 24-d treatments. Results indicate that either spring or winter oat can be planted in the spring in the winter oat area if the winter oat has a short, facultative vernalization requirement.