Milo, J., Department of Medicinal and Spice Crops, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50 250, Israel
Levy, A., Department of Medicinal and Spice Crops, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50 250, Israel
Palevitch, D.
Ladizinsky, G., Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel

The effect of colchicine induced autotetraploidy on the thebaine content and yield of the capsules of Papaver bracteatum was studied. A significant increase in the thebaine content of the capsules was found in tetraploid plants during two consecutive growing seasons, but the thebaine yield per plant was slightly reduced in the autotetraploids. Autotriploid plants showed a very high concentration of thebaine (8.8%) only in the first growing season. Preferential bivalent pairing and a relatively high pollen fertility were observed in the tetraploids, thus making possible the stabilization of tetraploidy by selfing. Tetraploidy seems a most promising approach for developing clones (by vegetative propagation) or lines rich in thebaine. © 1987 Veenman B.V.