EFFECT OF WATER STRESS ON THE GERMINATION OF BROME GRASSES (Bromusspp.) SEEDS USING POLYETHYLENE GLYCOL 6000

The germination phase is one of the most sensitive to the effects caused by the stress steps. The present work deals with the impact of water deficit expressed by lowering the water potential on germination percentage and the average germination time in three species of Bromus: B. madritensis L., B. lanceolatus Roth. and B. rubens L. Water stress was simulated using polyethylene glycol 6000 (PEG6000), according to different levels of water potential (- 0, 03; - 0, 7; - 1; -1,6 M Pa). The results obtained showed that water stress has a negative effect on the germination potential of the three species; the germinative behavior of these species under water stress, differs according to the species and the concentration of the PEG 6000 applied for most studied variables. Indeed, a maximum of 100%, 90% and 86% was achieved respectively for B. madritensis, B. rubens, B. lanceolatus to the water potential 0 MPa. At the lowest water potential (-1.6 MPa), the percentage of germination was slightly reduced, and was about 100%, 80%, 83.33%, respectively for the three species. Concerning the average germination time, there are no differences between the species studied, it lengthens slightly depending on the intensity of the water stress. In the light of these results, differences in sensitivity between the species appear and allow them to be classified according to the following decreasing tolerance sequence: B. madritensis> B. lanceolatus> B. rubens.