The chromosome morphology, secondary association and origin of cultivated rice

Morphological and Cytological Studies in the Genus <i>Calceolaria</i>

“…Secondary associa tion is more marked at Metaphase II. This has been found to be so by Lawrence (1931 ), Muntzing (1933) and Nandi (1936). In Calceloaria also the association at the second division is more marked than at the first.…”

“…Catcheside (1937) found a similar arrange ment in Brassica oleracea. But where the bivalents were associated the arrangement differed widely from the expected arrangement, as Nandi (1936) found in Rice. Nandi states that associated bivalents behave as units, so preserving the arrangement comparable to float ing magnets.…”

“…These observations have been criticised by Clausen (1921), Sax (1931) and Adati (1933). Secondary association has now been studied in a large number of plants and good reviews are given by Lawrence, Muntzing (1933), Alam (1936), Nandi (1936), Iyengar (1939.…”

“…On this basis it has been shown that in rice, where the haploid number is twelve (Nandi, 1936) the basic number is five. Similarly, in some of the apparent diploids reduplication of certain chromosomes has taken place, giving fertile species.…”

Variation in Nucleolar Number among Varieties of Cultivated Rice

“…According to Nandi (1936), two pairs of SAT-chromosomes occur in rice. However, since the observation on detailed structure of chromosomes is so difficult in this plant, his conclusion may not be reliable.…”