The effect of plant age at the time of treatment on the response of radish to daminozide

Abstract

Treatment of radishes ( Raphanus sativus L.) with daminozide usually causes an increase in the root:shoot ratio, but occasionally the effects are inconsistent. To obtain information on the cause of this inconsistency, daminozide was applied, at a dose of 2 mg per plant, to radish plants of differing ages. Eight- and 12-day-old plants showed only small and transient effects, 14- and 16-day-old plants produced a significant increase in root weight and root:shoot ratio, but treatment of 20-day-old plants resulted in detrimental effects. Morphological examination indicated that the onset of storage root swelling was important in determining the response of radish to daminozide application. Maximum stimulating effects on root weight and root:shoot ratio were obtained when plants were treated just prior to the initiation of storage root swelling. The failure to recognize this previously may have contributed to the occurrence of occasional inconsistent results.