Induced variation in quantitative traits due to physical (gamma rays), chemical (EMS) and combined mutagen treatments in soybean [Glycine max L.)Merrill]
Authors:
M. H. Khan and S. D. Tyagi: Department of Plant Breeding and Genetics K.P.G. College, Simbhaoli, Gaziabad (U.P)
Abstract:
Abstract Seeds of these two soybean genotypes viz., Pusa-16 and PK-1042 were exposed to various doses of gamma rays, ethyl methane sulphonate (EMS) and combination of both. Observations on germination %, lethality % (30 days after sowing and at flowering) and pollen sterility were recorded on M1 generation. The results indicated that a reduction in the germination percent over control was noticed in all the mutagenic treatments in both the cultivars. In general, reduction in germination percent was associated with the increase in the dose/concentration of the mutagen. The LD-50 for Pusa-16 was found to lie between 30KR + 0.2% EMS and 45 kR + 0.2% EMS, while in PK-1042, it was found to lie between 30 kR and 45 kR gamma rays and in between the higher doses/concentrations of combined treatment. In case of pollen sterility combined treatment exhibited high percentage of pollen sterility followed by EMS and gamma-rays. In Pusa-16, the increase in the dose/concentration of gamma rays and EMS was associated with the increase in the pollen sterility percent, while in combined treatment, the increase was noticed upto the intermediate dose level followed by decrease at higher level. On the other hand in PK-1042, increase in EMS concentration was associated with increase in sterility percent, while no definite trend was noticed in gamma rays and combined treatment. Key words: Gamma rays, EMS, germination, lethality, pollen sterility, soybean.
EVOLUTIONARY ASPECTS MICROSPOROGENESIS AND MICROGAMETOGENESIS INTERSPECIFIC HYBRIDS WITHIN THE GENUS Glycine L.
Authors:
Margarita Kozak
Abstract:
Abstract A cytogenetic study of interspecific Glycine max & G. soja hybrids was made. The F1 - F2 meiosis and pollen formation was studied on preparations stained by Felgen and by acetokarmin. The range in pollen diameter variability of interspecific hybrids proved significant: 9, 6-31, 2 mkm, and giving evidence of some meiotic disturbances in the process of microsporogenesis. Chromosomes of interspecific hybrids are from desynaped bivalents univalents during diakinesis - metaphase-I. The interspecific hybrid chromosome composition arises because of chromosome dissimilarity caused by the taxonomic differences in soja bean species under study. Genome isolation in hybrids and chromosome conjugation within each of the genomes confirmed the hypothesis on the leading role of polyploidy in the phylogeny of G. max and G. soja. Keywords: Glycine max, G. soja (G. ussuriensis), wild soybean, phylogeny, Interspecific hybrid, Microsporogenesis, meiosis, Microgametogenesis, pollen.