اثر تنش آبي ناشي از پلي اتيلن گلايكول بر خصوصيات جوانه زني بذر گياه ريحان

Effect of PEG Induced Water Stress on Seed Germination Characteristics of Basil (Ocimum basilicum).

Soil water supply is an important environmental factor controlling seed germination. If the water potential is reduced, seed germination will be delayed or prevented. Basil (Ocimum basilicum) is an annual herb plant of Lamiaceae family. The essential oil of basil, mainly used in food industries and perfumery, also possesses antimicrobial activity. To study the effects of water stress on seed germination and seedlings growth of basil, an experiment in completely randomized design with seven treatments and three replications was conducted. Seeds were subjected to water stress using polyethylene glycol (PEG 6000) at seven concentrations (0, 5, 15, 20, 25 and 30%) representing water potentials of 0, -0.03, -0.19, -0.41, -0.67, -0.99 and -1.35 MPa. The results showed that water stress have significant effects on seed germination of basil. Seeds treated with -1.35 MPa did not germinate. The few seeds that did germinated in -0.67 and -0.99 MPa water potential, did not produce seedlings. There was no significant difference between 0 to -0.41 MPa for germination percentage. Germination rate showed significant reduction at -0.41 compared to 0, -0.03 and -0.19 MPa water potential. On the other hand, the results of this study showed that different levels of water potential (0, -0.03, -0.19 and -0.41 MPa) have significant effects on seedling growth. With decreasing water potential (from 0 to -0.41 MPa), plumule length, fresh weight of radicle, plumule and seedling decreased but radicle length, dry weight of radicle, plumule and seedling, the radicle length to plumule length ratio and the dry weight of radicle to dry weight of plumule ratio increased. It could be concluded that in water stress condition, root growth of basil was affected lower than shoot growth.