Characterization of weed beet in Germany and Italy

Abstract

Weedy annual forms of beet (Beta vulgaris L.) cause crop failure and complicate the harvest and processing of sugarbeet (Beta vulgaris ssp. vulgaris var. altissima) in several areas of Europe. Hybridization between sugarbeet and wild annual forms of sea beet (Beta vulgaris ssp. maritima) in the French sugarbeet seed production area is a major source of weed beet in northwestern Europe. In the other principal seed production area, the Italian Po-Valley, inland wild beet is absent but local annual weed beet plants grow near sugarbeet seed production fields, suggesting an important role for this primary' weed beet in seed contamination. Because both coastal sea beet and primary weed beet forms could be sources for seed contamination and distribution of secondary' weed beet into German sugarbeet production areas, morphological and genetic traits of German and Italian weed beet were compared. Frequency of multigerm plants, frequency of annuals, hypocotyl color, and genetic relationships revealed by RAPD-PCR were examined. Results of the research indicate that: 1. German weed beet had some similarity to sugarbeet, but the weed beet clearly had a hybrid ancestry that included annual wild beet of unknown origin. 2. Italian weed beet had some similarity to sugarbeet, but the weed beet clearly had a hybrid ancestry that included annual sea beet. 3. German weed beet usually grows far away from coastal sea beet. The annual weed beet must have arrived as a contaminant of sugarbeet seed, and therefore is of secondary' origin. 4. Italian weed beet biotypes were hybrids, but they could be 'primary', as the result of hybrid seed produced in seed production fields or in wild coastal populations, or they could be 'secondary' as contaminants of sugarbeet seed sold to Italian farmers. These results supported the hypothesis, that primary weed beet in Italy is likely to be responsible for the production of secondary weed beet, which is sold as contaminants to farmers in Italy and Germany. Therefore, contamination avoidance strategies in seed production areas should concentrate both on the control of weedy primary-type beet as well as isolation from wild sea beet. Additional