Cyto-genetics of Millets (2)

抄録

1. A detailed cytological study of millets like Eleusine coracana, Setaria italica, Panicum miliaceum, Panicum cruss-galli and Pennisetum typloideum with their closely allied species was taken up for the first time. Differences in chromosome numbers already reported in some species have been found.
2. Mitosis and meiosis in all the species is described. Analysis of somatic chromosomes has been done.
3. Pairing at diakinesis was found to be by means of chiasmata. Chiasmafrequency was analysed in the pollen mother cells of E. coracana, E. indica, E. verticillata and D. aegepticum. It was found that with the advancement of meiosis the total number of chiasmata decreases but the proportion of total chiasmata that are terminal increases from diakinesis to metaphase.
4. Secondary pairing occurs amongst the bivalents at metaphase I or univalents at metaphase II. The maximum association has been studied in millets. No connections which have been reported to arise by fusion at pachytene and causing the secondary association amongst the chromosomes have ever been observed.
5. Two original basic numbers have been found out by means of secondary association studies in millets.
6. Linear micro-morphological studies in these genera have been persued and effect of polyploidy has been noticed in some respects.
7. It was obvious that alto-polyploidy and the establishment of a secondary basic number are important factors in evolution.
8. Origin of millets has been determined with details and hypothesis is advanced showing a monophyletic origin of family Gramineae. In the origin of millets and their allied species included here, polyploidy, aneuploidy and structural changes have played important role at various stages.
9. Chromosome pairing at meiosis in Panicum and Pennisetum have been discussed. These genera have autoplolyploid species.
10. Fertility of millets and their allied species has been studied and the causes of varying fertility in among the members of this group has been found out.