Abstract
Cytogenetical study on the colchicine-induced autotetraploid of Oryza glaberrima was carried out. As compared with the diploid, the autotetraploid increased in stomata length, length of penultimate leaf blade, pollen diameter and seed size; decreased in plant height, first internode length, number of panicles, number of spikelets per panicle, pollen stainability and seed fertility. The differences between them were conspicuous in number of panicles, number of spikelets per panicle, seed fertility and seed size. The autotetraploid had multipored pollen grains and awned seeds, which was different qualitatively from the diploid. In pollen mother cells of the autotetraploid, 2 to 12 IV were observed at the stage of diakinesis to metaphase I, and 8IV+8 II most frequently. The mean meiotic chromosome configuration was 7.63IV+0.08 III+8.51 II+0.23 I. The meiotic chromosome configurations observed in the present study could be explained by a hypothesis postulated by Jackson and Casey (1980, 1982) with random pairing among four homologous chromosome arms and a maximum two chiasmata per bivalent.
