اثر تنش خشكي با استفاده از پلي اتيلن گليكول (PEG 6000) در محيط كشت جامد روي خصوصيات گياهچه ژنوتيپ هاي چغندرقند

Effect of water stress induced by solid medium of poly ethylene glycol (PEG 6000) on the seedling characteristics of sugar beet genotypes

Solid medium of poly ethylene glycol (PEG 6000) was used to induce various levels of water stress for evaluating the reaction of seedlings of 20 different genotypes of sugar beet under water stress conditions. Fifteen restorer lines (O-Types) are tolerant of drought and five genotypes (control) with three of them tolerant one moderately-tolerant and one sensitive to drought as well as four drought stress levels of osmosis potentials: 0, -0.6, -0.7 and -0.8 MPa (from combination of 0, 15, 20 and 25% PEG, respectively). A factorial arrangements (4^20) in CRD with three replications was employed in the tissue culture environment. In each experimental units shoot and root length, shoot fresh weight and dry weight of shoots and roots in all seedlings were determined following growth of sugar beet genotypes in the solid media of PEG for 30 days. The ANOVA showed that the main effects of water stress, genotype and their interactions were significant (P<0.01) on shoot and root fresh weights. Effect of genotype was significant (P<0.0 i) for shoot and root lengths. There was significant interaction for shoot length (PO.Ol) and root length (P<0.05). Results confirmed that there was high genetic variation among sugar beet genotypes under water stress conditions. Genotypes G16 and G18 among checks and genotypes G10, G4, G7 and G5 among O-types showed the least reduction in all traits as compared with to the other genotypes. It could be concluded that under water stress condition (up to 0.6 MPa in PEG medium), root length and root fresh weigth seems to be suitable traits in sugar beet seedlings genetic diversity-assessment.