COILING OF ALFALFA PODS IN RELATION TO RESISTANCE AGAINST SEED CHALCIDS: ADDITIONAL OBSERVATIONS

A study of seed chalcid (Bruchophagus roddi) infestation of pods in an Iowa nursery of diverse populations of alfalfa revealed the same selective pattern previously discovered in an Ottawa nursery. Although possessing fewer and lighter seeds, and present in the nurseries in lesser proportion, pods with limited or no coiling were much more heavily infested than highly coiled pods. In uncoiled pods infestation was highest in the middle portion of the pod. However, with increasingly coiled pods, infestation became progressively restricted to the ends of the pod. These observations are consistent with the hypothesis that pod coiling per se provides protection against seed chalcids. Avoidance of glandular pods by the chalcid was not evident, although this has been indicated elsewhere.Key words: Medicago sativa, Bruchophagus roddi, breeding