Development of forest trees with enhanced drought tolerance

Improving selection by combining physiological and morphological methods for examination of trees responses to drought under controlled conditions and in the field


Global climate-change scenarios in the Mediterranean region forecast rising temperatures, reduced rainfall amounts and a generally drier climate. The rapidly changing climatic conditions might put perennial species, particularly trees, in danger because of their inherent slow adaptation rates. For afforestation in drylands under a changed climate, there is a need for more drought tolerant trees.

This study focusses on a combination of physiological and morphological methods for selection of genotypes with enhanced drought tolerance. Model tree species used for afforestation in Israel are the evergreen conifer Aleppo pine (Pinus halepensis) and the deciduous broad-leaved Atlantic pistachio (Pistacia atlantica). Mother trees showing features of adaptation to drought in dry southern Israel serve as seed sources for this project. Seeds of each mother plant are evaluated for indices of drought tolerance by three different approaches:

1) transpiration under drought treatment as assessed by lysimeters on the whole-plant level;

2) sensitivity to xylem embolism as determined by ultrasonic acoustic emission;

3) growth rate of an efficient root system as assessed under standard and drought conditions.

Drought tolerance of seed sources tested under controlled conditions will also be evaluated in the field. The findings of this project will assist in selecting drought tolerant seed sources for afforestation under a future drier climate. In addition, the studies will deepen our understanding in the ecophysiological and morphological processes related to drought tolerance in trees.

Collaboration: Rony Wallach, the Hebrew University of Jerusalem, Rehovot, Israel
Menachem Moshelion, the Hebrew University of Jerusalem, Rehovot, Israel

Co-workers: Dana Sarid (MSc student)

Partner organizations: Ministry of Agriculture and Rural Development KKL – Jewish National Fund