Comportement des semis du cèdre de l'Atlas en conditions de stress thermique.

Abstract

Natural disturbances and human but also the changes expected for the next century are likely to substantially and permanently alter ecosystems and their diversity. Future climate changes are likely having an irreversible impact. The adaptation of tree species composing these ecosystems may be difficult because the speed of climate change may not allow them to gradually migrate to more favorable areas. In this context, our work focuses on the aspect of adaptive capacity and tolerance of seedlings of cedar Atlas under conditions of heat stress in the region of Batna and semi-controlled conditions where the plants suffer a thermal shock a period of three hours at temperatures between -10 ° C and 44 ° C. Batna region enjoys a Mediterranean semi-arid climate with a cold Q2 = 32, m =- 0.43 ° C and M = 36.22 ° C. The study area was treated on the thermal and revealed a multitude of stress winter, spring and summer. The accumulation of various osmolytes (soluble sugars, proline, and protein) shows predominance in the new shoots, old shoots, stems and roots. Chlorophyll undergoes a total decline of 50% mainly in the new shoots. Stomatal regulation is manifested by a closure 12h at temperature close to 34 ° C. The applied stress naturally or experimentally induced structural changes affecting the variations in accumulation of various osmolytes and chlorophyll thus demonstrating the ability to adapt to heat stress. The temperature range -6 ° C, -10 ° C and 44 ° C is characterized by the most important concentration of osmolytes in the organs of seedlings