Physiological response of the facultative halophyte, Aeluropus littoralis, to different salt types and levels

Abstract

The present study investigated the effects of NaCl, KCl and Na₂SO₄ salts on the C₄ excreting halophyte Aeluropus littoralis in relation to growth, mineral status and photosynthesis in greenhouse conditions. Plantlets were subjected to five salinity levels: 0, 200, 400, 600 and 800 mM for 30 days. Growth decreased progressively with salinity increase, its reduction might be correlated with the high sodium (and/or chloride) accumulation in plant tissues, the decrease of leaf water status and the decline of the net photosynthetic rate and the intrinsic water use efficiency. Na₂SO₄ appeared more toxic than KCl and NaCl, especially at 200 mM. At 200 mM, Na₂SO₄ reduced plant growth by 61% while for other salt forms, the reductions were less than 20%. At this salt level, stomatal conductance showed a consistent pattern with plant growth and could adequately explain the variations between the effects of the three salt types.

Keywords:

• Aeluropus littoralis
• internal CO₂ concentration
• mineral status
• photosynthetic rate
• stomatal conductance
• salt stress

Abbreviations:

• A, photosynthetic rate
• Ci, internal CO₂ concentration
• DM, dry mass
• E, transpiration
• FM, Fresh mass
• gs, stomatal conductance
• L, leaves
• R, roots
• S, stems
• SL, salt level
• ST, salt type
• WP, whole plant
• iWUE, intrinsic water use efficiency