Biogeosciences and Forestry Biogeosciences and Forestry Drought tolerance in cork oak is associated with low leaf stomatal and hydraulic conductancesTouhami Rzigui (1-2) , Latifa Jazzar (1) , Khaoula Ben Baaziz (1) , Sondes Fkiri (1) , Zouheir Nasr (1) To investigate the role of seeds origin in drought tolerance, the response to water deprivation of cork oak seedlings differing in climatic conditions at their geographical origin was compared. Gaâfour is the provenance from the driest site and Feija is the provenance from the wettest site. Net photosynthesis (An), stomatal conductance (gs) and leaf water potential were measured during dehydration. A delayed decrease in leaf water potential is observed after water withholding in Gaâfour as compared to Feija leaves. At the onset of dehydration, An and gs were higher in Feija. After withholding watering, Gaâfour leaves were able to maintain a higher An and gs than Feija leaves. Most likely, drought tolerance in Gaâfour leaves is associated to their lower gs under wellhydrated conditions. The stomatal density (Ds) and specific leaf area (SLA) were not different in well-watered leaves but, leaf hydraulic conductance was lower in Gaâfour leaves when compared to Feija leaves. Our results suggested that lower stomatal and hydraulic conductances of Gaâfour leaves could be involved in bringing about the better resistance to dehydration.

The current work was done Artemisia herba-alba and Artemisia compestris essential oils harvested from the Eastern Algerian Sahara, their insecticidal characteristics against the eggs and adults of the date moth Ectomyelois ceratoniae. Indeed, two treatment modes were used; by contact application on eggs and by inhalation against adults. It appears from the results that the hatch rates were less than the hatching rate recorded in the control (96% ±00.00). The hatching rate reported on eggs treated by the highest dose (160 μl/ml) of Artemisia herba-alba and Artemisia compestris essential oils are 16.66 ± 08.81 and 37.77 ± 13.47 respectively. Statistical treatment results by the Chi-square test (χ2), attest that the treatment by A. herba-alba and Artemisia compestris essential oils at the same dose (160 μl/ml) affect significantly (χ2 = 35.62, p = 0.00 and χ2 = 21.17, p = 0.00 respectively) the hatching rate compared to the control. The sensitivity of adults to essential oils is expressed by 100% mortality rates obtained after 10 min of treatment by the highest doses (80 μl/ml and 160 μl/ml) of A. herba-alba essential oils, the same mortality rates (100%) were notified with the same doses (80 μl/ml and 160 μl/ml) after 20 min and 15 min of treatment by Artemisia compestris essential oils respectively. The dose-dependent mortality data revealed that there was a significant difference between the five doses of A. herba-alba essential oil tested except at the last treatment time (20 min) for which it was appeared p = 0.571, while for A. compestris essential oil, a significant difference was recorded with p varying between 0.00 and 0.003. The lowest LD50 value (0.09 μl/ml and 16.71 μl/ml) were noted during the longest treatment time (20 min), while the highest LD50 value (75.85 μl/ml and 263.7 μl/ml) were found during the shortest time (5 min) of A. herba-alba and A. compestris respectively. J. Bio-Sci. 29(2): 09-17, 2021 (December)