STUDIES ON THE CHROMOSOME DOUBLING OF WHEAT POLLEN PLANTS

Studies on chromosome doubling of wheat pollen plants have been conduc ted, and a simple and efficient procedure for increasing the chromosom e doubling frequency of wheat pollen plants was developed. Culture of the pollen calli on a colchicine-containing medium before transferring them to the regeneration medium increased the chromosome doubling fre quency of the plants derived from these calli. The suitable concentrat ion of the colchicine in the medium was around 250 mg/l, and the optim um duration for the calli to stay on the colchicine-containing medium was 1 day. Under these conditions, the chromosome doubling frequency o f the pollen plants was greatly increased, but the ability of the call i to differentiate green shoots was generally not affected. The abilit y of the calli to differentiate green shoots was lowered mainly by a l ong duration of colchicine treatment. When the pollen calli were trans ferred to the regeneration medium in two or three batches, the pollen plants derived from the second batch of calli showed significantly hig her spontaneous chromosome doubling frequency than the plants derived from the first batch of calli.