Intraspecific Variability To Drought Impacts In Pinus Halepensis Provenances Trials

Understanding how tree species respond to drought in their natural environment is needed to predict forest adaptation and management practices under global environmental changes. This study was carried out to determine physiological and biochemical responses to variations in environmental conditions of three provenance of Pinus halepensis. Our study consists in particularly to determine the intra-specific variability in water deficit responses of Aleppo pine using gas exchange measurements and biochemical markers such as proline, soluble sugars content, and chlorophyll pigments. The results showed a significant difference between the three provenances of Aleppo pine. The considerable decrease in photosynthetic capacity during the summer season coincides not only with the reduction of stomatal closure but also with a gradual decline in the content of chlorophyll pigments. In addition, a very important accumulation of proline and sugars in the aerial organs was recorded during the summer season, especially in the Italian provenance. Gas exchange exhibited significant differences (p < .05) among the months studied, with the highest values being for March (with greater water availability). Our results underscore the need to consider seasonal drought tolerance when selecting tree species for specific reforestation sites.