Abstract only

Modem forms of conservation of plant genetic resources are based on their storage in seed banks, which has become a common practice. Maintenance of constant low temperature and partial oxygen pressure, as well as absence of moisture and micro- flora establishes environment, which provides for long-term preservation of seed viability (Viability of seeds, 1978). But even under such conditions, seed ages and loses its viability. At the same times, data is available on differences in duration of seed vitality (Danilovich, Sobolev, 1982), suggesting that genotype may influence seed vita1ity. Therefore, differences among the genotypes in the rates of seed aging may be expected. The objective of the present study is to work out a quantitative criterion to estimate genotypic potential of seed storage lifes. Material of the study involved different bread wheat genotypes including Graecum, Diamant and Eritrospermum-841. Simulation of the process of seed aging was carried out according to the widely accepted methodology (Justice, Bass, 1978; Naylor, 1989). Cytogenetic analysis of the frequency of chromosome aberrations in plant root meristem cells (Mekhtizadeh, Sinicina, 1987) was employed to estimate the genetic consequences of aging. In the picture is shown the impact of aging on the dynamics of chromosome distortions and germinating power of seeds in the genotype of wheat Graecum. The picture shows that the signs of seed aging are observed already during their short-term (3-6 days ) keeping under increased temperature ( 40°C) and humidity (95%). This is manifested in the exponential reduction of seeds ' germinating ability and increased frequency of chromosomal aberrations in the root meristem cells. A negative correlation has been found between these parameters. Similar results were obtained in a comparative study of genetic consequences of the natural and artificial aging of seeds carried out on two contrasting by salinity- and drought-resistance genotypes of wheat Diamant and Eritrospermum -841. Genetic consequences of aging have been found to occur during a long-term storage of seeds ( 15 years ), even if kept in a refrigerator. The frequency of chromosomal aberrations in the root meristem cells of the tested plants is higher as much as twice as compared with the check. Genetic differences in seed aging rates can be identified through this approach as manifested in different intensity of increase of the chromosomal aberrations. Intensity of increase of the chromosomal aberrations in the unstable genotype Diamant is doubled compared to that of the stable genotype Eritrospermum-841. The same differences are observed for these different genotypes upon artificial aging as well. Thus, a methodology and a quantitative criterion for forecasting the genetic potential of seed longevity under different storage conditions have been established and developed.

English

0408|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection