Uptake and translocation of carpropamid in rice (Oryza sativa L).

Translocation of the antiblast compound, carpropamid, was investigated in rice using [14C]carpropamid. When applied to the seed, carpropamid was not only readily absorbed but was translocated to different parts of the seedlings emerging from treated seeds. A substantial portion of fungicide appeared to be exuded onto the leaf surface. In 21-day-old plants grown from [14C]carpropamid-treated seeds, 27.2% of the radioactivity isolated from leaves was present on the surface of lamina. This exuded fraction is probably responsible for its action as a fungal anti-penetrant compound. Following 30-min root dipping of 14-day-old seedlings, carpropamid was rapidly absorbed and translocated throughout the seedling. Its intra-laminar distribution was uniform as determined by autoradiography. Only a small fraction (< 2%) of fungicide applied to the foliage was translocated beyond the site of application within the treated leaf. Translocation was primarily apoplastic. Approximately 54% of the radioactivity recovered from leaves was in the form of carpropamid. At least seven radiolabelled metabolic products were observed by TLC. Only 8.3% of radioactivity applied through the seeds could be recovered from 21-day-old seedlings.