Sodium and potassium allocation under drought stress in Atlas mastic tree (Pistacia atlantica subsp. mutica)

Abstract

Sodium and potassium ions have crucial roles in drought tolerant mechanisms of plants. In a pot experiment, seedlings of Pistacia atlantica subsp. mutica were cultivated in a silty clay soil (Kex=21 mg/l, Naex=143 mg/l) and exposed to different levels of soil water content (90, 65 and 45% FC). P. atlantica maintained leaf transpiration rate, and relative water content and cation (Na+ and K+) content of different organs under moderate water deficit (above permanent wilting point). At higher water shortage, the amount of transpiration rate and the relative water content of tissues were reduced, but the amount of Na+ and K+ remained unaffected even under severe drought stress (below permanent wilting point). Generally, the amount of K+ content in plant organism was higher than that of Na+. The amount of root to shoot Na+ was higher than that of K+. Potassium contents of leaves and stems were positively related with transpiration rate, whereas Na+ contents of roots and stems were positively related with root relative water content. Roots and stem of Atlas mastic tree seedlings exhibit high drought tolerance index for Na+ and K+.