Abstract:

Two switchgrass cultivars were investigated to reveal the effects of salt stress on the physiological and growth indexes of Panicum virgatum. The salt tolerance, physiological and growth responses of Alamo and Pathfinder cultivars cultured in Hoagland solution supplied with NaCl, Na₂SO₄ and mixed neutral salt (NaCl:Na₂SO₄=1:1) at the concentrations of 0, 50, 100, 200 and 300 mmol·L^-1 were studied in seedling stage. Physiological indexes (chlorophyll content, permeability of plasmas membrane, soluble sugar and soluble protein) were measured after salt stress for 7 days and so were growth indicators (height, tiller number, total root length, total root surface area, dry weight of shoot and root) after 30 days. The results showed that both cultivars actively adapted to the condition of low concentration (<100 mmol·L^-1) compared with the control. The growth and physiology of both cultivars were inhibited with increasing salt concentration. Height, tiller number, dry matter and chlorophyll content decreased with the gradient enhancement of salinity concentration; whereas the permeability of plasmas membrane, soluble sugar and soluble protein increased with the gradient enhancement of salinity concentration; total root length and surface area were also restrained. Integrated analysis implied that the Na₂SO₄ stress exerted stronger inhibitory influence on switchgrass than the NaCl and mixed neutral salt stress.

Key words: Neutral salt-stress, Switchgrass, Growth, Physiological characteristics

摘要：

为研究柳枝稷(Panicum virgatum)耐盐程度及其在盐胁迫处理下的生理和生长反应,选用2个柳枝稷品种‘Alamo’和‘Pathfinder’,采用3种中性盐(单盐NaCl, Na₂SO₄以及混合中性盐NaCl+Na₂SO₄),设0(CK), 50, 100, 200和300 mmol·L^-15个盐浓度,分别对柳枝稷进行胁迫处理,测定胁迫7 d的叶绿素含量、质膜透性、可溶性糖和可溶性蛋白,以及胁迫30 d的株高、分蘖、总根长、总根表面积、地上部和地下部干重.结果显示:低浓度(100 mmol·L^-1)盐胁迫条件下,2品种柳枝稷均能从生理和生长等方面表现出积极适应胁迫生境的趋势;随着盐浓度的增加,2品种柳枝稷的生长和生理受到显著抑制,但2品种的柳枝稷对不同的盐分表现出的耐盐能力不尽相同.3种中性盐中,Na₂SO₄对柳枝稷的胁迫程度大于NaCl和混合中性盐.

关键词: 中性盐胁迫, 柳枝稷, 生长, 生理特性