Abstract:

Betula microphylla var. paludosa is a salt tolerant plant and naturally grows in inland. In order to explore possibility in transplanting the species to marine salina, we investigated photosynthetic performance and leaf anatomic structure of B. microphylla , grown under control (nutrient soil) or salt-stress conditions (nutrient soil containing different salinity: 2‰, 4‰, 6‰, 8‰ of the solution for 60 days. The species had normal photosynthetic performance and leaf anatomic structure under lower salinity conditions. When soil salinity increased (≥0.4%), the net photosynthesis rate, stomatal conductance, transpiration rate, internal CO₂ concentration, and chlorophyll content in leaves all decreased, whereas the soluble sugar, proline and protein contents of leaf increased. Accordingly, cells of the palisade tissue in B. microphylla var. paludosa leaf elongated and piled closely, in comparison with that under lower salinity conditions, and the chloroplasts changed from elliptical shape to round shape and in which many 1ipid droplets and starch grains occurred in it. These results indicated that B. microphylla var. paludosa could tolerate salt-stress through modifying leaf physiological and morphological traits, reflecting an adapting potential to saline.

Key words: Betula microphylla var. paludosa, salt stress, net photosynthesis rate, soluble sugar, microscopic structure, ultrastructure