沙埋对两种沙生植物幼苗生长的影响及其生理响应差异

为了解沙埋对沙生植物生长的影响及其生理响应特征, 比较不同沙生植物耐沙埋能力及其机制, 2010年在内蒙古科尔沁沙地研究了不同深度沙埋下沙蓬(Agriophyllum squarrosum)和盐蒿(Artemisia halodendron)幼苗的存活率、株高等生长特性及其渗透调节物质含量, 保护酶活性和膜透性的变化, 得到以下结果: 沙蓬和盐蒿幼苗均具有较强的耐沙埋能力, 其中沙蓬幼苗最大耐沙埋深度超过幼苗10 cm, 盐蒿幼苗最大耐沙埋深度超过其株高8 cm; 随着沙埋深度增加, 沙蓬和盐蒿幼苗的存活率和株高均显著下降, 沙蓬的下降幅度显著小于盐蒿; 沙埋处理下两种植物均未表现出受水分胁迫, 沙埋导致其光合面积下降, 幼苗顶土困难, 是影响其存活和高生长的主要生态机制; 随着沙埋深度增加, 沙蓬幼苗丙二醛(MDA)含量显著增加, 盐蒿幼苗MDA含量下降, 虽然二者膜透性均呈增加趋势, 但沙蓬膜透性增加幅度显著低于盐蒿, 说明细胞膜受损是导致二者幼苗存活率下降和生长受到抑制的主要生理机制, 沙蓬膜透性受损程度较低是其耐沙埋能力较强的主要生理机制; 沙埋胁迫下, 虽然两种植物都通过提高过氧化物酶活性和脯氨酸含量减轻细胞膜受损程度, 但沙蓬体内超氧化物歧化酶也表现出重要协调作用, 使之酶促系统在保护细胞膜免受胁迫损伤过程中的作用更有效。

Effects of sand burial on growth in two psammophyte seedlings and differences in their physiological responses

Aims Our objectives were to determine effects of sand burial on growth and physiological response in psammophytes and to compare differences in abilities and mechanisms of different psammophytes to resist sand burial. We examined changes in survival rate, plant height, osmotic regulation substances contents, protective enzymes activity and membrane permeability of Agriophyllum squarrosum and Artemisia halodendron with different sand burial depths during 2010 in the Horqin Sand Land of Inner Mongolia.
Methods There were ten sand burial treatments: buried to 0% (CK, no burial) and 25% (A), 50% (B), 75% (C) and 100% (D) of seedling height and 2, 4, 6, 8 and 10 cm above seedlings. Every treatment consisted of four replicates. Stress physiology properties were measured 10–12 days after sand burial, and plant height and survival rate were measured in late August.
Important findings With increased sand burial depth, both survival rate and plant height of Agriophyllum squarrosum and Artemisia halodendron decreased significantly, with a greater decrease in Artemisia halodendron. The maximum depth to resist sand burial exceeded 10 and 8 cm of seedling height for Agriophyllum squarrosum and Artemisia halodendron, respectively. The two psammophytes showed no water stress under sand burial stress. Decreased photosynthetic area and increased difficulties to emerge from the soil were the main factors that inhibited the survival and growth of the psammophyte seedlings. With increased depth of sand burial, malonaldehyde content increased significantly for Agriophyllum squarrosum and decreased significantly for Artemisia halodendron. The increased magnitude of membrane permeability was significantly lower in Artemisia halodendron. Injury of the cell membrane was the main physiological mechanism to decrease survival rate and inhibit growth in the psammophyte seedlings under sand-burial stress. Also, lighter membrane damage was the main physiologicalmechanism that gave Agriophyllum squarrosum stronger resistance to sand burial. Although both species reduce plant cell membrane damage and degree of cytoplasm leakage by increasing peroxidase activity and proline content under sand burial stress, superoxide dismutase also showed an important coordinating role for Agriophyllum squarrosum that makes its enzymatic system more effective in the protection of cell membrane from stress injury.