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Project ID: QLK5-CT-2000-01377
Finanziato nell'ambito di: FP5-LIFE QUALITY
Paese: France

Information on drought resistance of P. euphratica for practical purposes

The degree of drought tolerance of the poplar Populus euphratica was tested by imposing a controlled water shortage to micro-propagated rooted cuttings grown in pots.

Two main lines of evidence showed that this species, despite its wide distribution in arid regions of Central Asia, displays only a very low drought tolerance:
- Its xylem, whether in leaves, in roots and in stems, is very prone to cavitation and embolism. Cavitation n induced losses of conductivity occurred already at still high levels of leaf water potential (above 1 MPa), which makes this species one of the most vulnerable species among all those tested until now. Among the three poplar species tested, it was the most vulnerable one. This high vulnerability resulted in the induction of significant losses of conductivity during drought stress in situ, which is a seldom occurrence among forest trees.

- During water shortage, we observed very rapidly (at still high levels of water potential) growth cessation, and stomatal closure. Nevertheless, despite these rapid and severe responses, all tested plants recovered from stress after rewatering. This species therefore may be suited for afforestation under semi arid or even arid conditions, only in the case of the presence of a water table at reasonable depth. The ability of the P euphratica trees to reach such tables and to efficiently consume the available water, is the main explanation for its survival under such conditions. Anyway, afforestation with this species is probably a difficult task that may require heavy irrigation during the first years until the roots reach the water table. Aged populations of this species probably only little use sexual reproduction (seedlings may suffer drought and die) but rely on vegetative propagation based on root suckers that may develop and rely on the water supplied by roots from larger and adjacent trees. This information may be crucial for the success of afforestation program with this species.

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