Study On Embryology And Cytology Of Special Polyploid Rice(Oryza Sativa L.)

ABSTRACT SAR-3 and SAR-4 , which are autotriploid and autotetraploid respectively ,are derived from twin-seeding basic populations of 9003 and 9004. They have a very important character proved in earlier research: Some F-, populations of diploids F1 individuals from the cross of polyploid X diploid were uniform. Although 300 stable strains had been screened out from the progenies of the cross involved SAR-3 and SAR-4, the mechanism of stabilizing in early generation is not clear yet. So many unresolved basic researches were left for us. In this research ,two aspects were explored for 18 lines from SAR-3 and SAR-4: 瓹hromosome behavior during meiosis, especially chromosome segregation mode and the generating mechanism for n-gamate. ?Reproductive behavior of autotetraploid and embryo development for cross of autotetraploid X diploid. The main results are as following: 1 The results of pollen stainability identified with the method of 12-1(1 revealed that autotriploid SAR-3 pollen stainability was very low(26.73%) but higher for autotetraploid SAR-4?s(89.93%) 2 The autopolyploid PMCs were observed and the results showed: (i7)In autotriploids SAR-3, the average paring form was 7.85111+4.7111+3.031 at diakinesis and 6.80111+6.1911+3.221 at metaphase 1. The equilibrium segregation was prevailing at anaphase I. Lag chromosomes were also observed at the same phase, which was probably the main reason for the formation of haploid gamete. ㊣n autotetraploids SAR-4, the average paring form was 8.881V+1.11III?.0211+1.l11 at diakinesis and 8.421V+l.12111+4.7011+1.521 at metaphase I. The equilibrium segregation was also prevailing at anaphase I. The absolute majority gametes had 24 chromosomes. 3 The identification for the ploidy of autopolyploids revealed that: the chromosomes of the progenies from SAR-3 had been changed from 25 to 29. In the identified 30 strains of SAR-4 progenies, most of them were still autotetraploid and only a few of them were aneuploid with 2n?6 or 47. 4 The research for the embryo sac structure of 4033 line of SAR-4 showed that: 66.33% embryo sacs were normal and 33.66% were not. And in the latter, multi-eggs, multi-polar nuclei, multi-antipodal cells and non-egg 2 apparatus were observed. 5 The seed-setting for the cross of autotetraploid 4033 X R725 was very low, but 80% haploid pollen can geminate on the pistile of tetraploid 4033, penetrate into, and arrive at micropyle. The barriers of crosses may occurre in fertilization, including single- (12.08%), non-fertilization (72.09%) ,abnormal or prolonged development of proembryo and degeneration of endosperm.