Physiological response of Argania spinosa (L.) Skeels seedlings subjected to a soil water deficit

摘要

The Argan tree (Argania spinosa (L.) Skeels), an endemic essence of North Africa, is a tree which resists periods of prolonged drought well. The effect of soil water stress as a result of an irrigation shortage has been studied on the leaves of plants aged two months cultivated in pots. Under moderate stress (68 to 25% of field capacity) the relative water content of the leaves varied from 86% to 62%. The seedlings overcome water stress by partial closing of their stomates and with osmotic adjustment resulting from a rapid and highly significant increase of active soluble sugars. In response to a more intense stress, the relative water content of the leaves reaches 50%, the closing of the stomates becomes significant but it is not total and the osmotic adjustment intensifies due to a rapid accumulation of proline. The various parameters studied show that the Argan seedlings present a strategy of resistance to dehydration characterized primarily by an aptitude for active osmoregulation and a partial stomatal regulation.