Differential responses in growth and solute composition to salinity in the halophytes Suaeda salsa and Limonium bicolor

摘要

Suaeda salsa, a leaf succulent, and Limonium bicolor, with leaf salt glands, are common halophytes in coastal saline areas in China; they have been proposed as possible species to expand cultivation on unfavorable land. Because of the differential adaptive characteristics of these two species to saline soils, the response of growth and solute composition to salinity in both species is unclear. Therefore, a comparative study was conducted to elucidate the effect of salinity on growth and solute composition of the two halophytes grown in hydroponics. For S. salsa, the presence of 50 mM and 100 mM NaCl was associated with 94% and 43% increase in shoot dry weight, and 87% and 47% increase in root dry weight, respectively, compared with the control. At the same NaCl concentrations, only 16% and 10% increase in shoot dry weights and 1% and 2% decrease in root dry weights, respectively, were found in L. bicolor. 400 mM NaCl significantly inhibited the growth of L bicolor. The accumulation of Na~+ in shoots and roots of both species increased significantly with increasing NaCl concentrations. However, increases of Na~+ concentrations were much larger in S. salsa than in L. bicolor. Ion accumulation and partitioning differed between the two species. S. salsa accumulated more ions than L. bicolor, and most ions were translocated to the shoots, whereas ion concentrations in the shoots and roots were approximately similar in L. bicolor. At higher salinity, the shoot soluble sugar concentrations decreased, and proline concentrations increased in both species. The shoots of L. bicolor contained relatively more soluble sugars and proline than those of S. salsa, especially at higher salinity levels.