Adaptation du chêne liège (Quercus suber L.) aux conditions extrêmes de température

Abstract

The climatic changes which the Mediterranean region knows are at the origin of the physionomical variations of the forest ecosystems. This pathology appears by thermal stresses which undergo the trees in their natural area, affecting their growth and productivity. The most disastrous consequences appear by a risk of displacement of their biogeographic areas. This study is articulated on the capacities of adaptation of cork oak to thermal variability using the biochemical markers (proline, soluble sugars, proteins and quercitol). Sowings have elevated under semi controlled conditions undergo three successive stresses of short duration of 3 hours to a range of temperature ranging between -2°C and 44°C. We have effected the measures of morphological parameters (hight of stream, number of leafs and foliar surface) and biochemical. The morphological parameters showed a statistically significant difference between the different treatments and stress. Soluble sugars (sucrose, glucose and fructose), the starch are closely linked with a reduction in their contents at stressed seedlings. The accumulation of the proline is correlated positively with the hot temperatures and accumulation of the proteins is significant at 2°C and 38°C. The quercitol is correlated with extreme temperatures (-2°C and 44°C). The roots and the young leaves (the 2nd flush) accumulated proline and quercitol. The accumulated quantities could be related to the level of tolerance to the thermal stress, contributing to the maintenance of cellular turgescence, creates by osmotic adjustment for these markers.