Germination response of drought tolerant sugar beets under mannitol induced osmotic stress
2001
Sadeghian, S.Y. | Yavari, N. (Sugar beet Seed Institute, Karadj (Iran))
Sugar beet genotypes screened for high water use efficiency and high sugar yield under drought stress condition in the field were examined for their germination and early seedling growth under osmotic pressure induced by mannitol solutions. Seeds of nine sugar beet lines including seven drought tolerant and two drought susceptible lines were washed, sterilized, dried, and sown in paper, perlite, and water agar as media for germination tests. Each experiment was conducted in three replications using a factorial design. Mannitol was used in all experiments as osmotic stress inducing substance at 0.0, 0.2, and 0.3M concentrations. Percentage of germinated seeds was recorded in all experiments and percentage of abnormal seedlings was added to the germination test performed in paper. The results revealed a very significant difference between levels of stress treatments and genotypes. By increasing mannitol concentration in paper very drought tolerant genotypes represented the highest germination rate and the lowest abnormal seedlings. Number of seedlings survived at 0.3 M mannitol level of agar was high in the known tolerant genotypes at final count and the ratio of viable plants in stress levels to germination percentage in non-stressed was characterized as a positive index in determining stress tolerant genotypes. It seems that drought tolerance is expressed even at a very early stage of sugar beet growth and the characters of seedlings in the stress conditions, can be considered as criteria for early screening of potentially drought resistant genotypes.
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