差巴嘎蒿幼苗对沙埋的生态适应和生理响应

沙埋对于沙漠植物存活和生长影响的研究文献已有很多,但迄今有关沙漠植物对于沙埋生理生态适应的研究还很少见有报道。差巴嘎蒿(Artemisia halodendron)广泛分布于我国半干旱沙地中,是流动半流动沙地的优势种。为了解沙生植物对沙埋的生态适应及其生理响应,2010—2011年在内蒙古科尔沁沙地研究了不同沙埋深度下差巴嘎蒿幼苗的存活率、株高等生长特性和渗透调节物质含量,保护酶活性和膜透性的变化,得到以下结果:沙埋对差巴嘎蒿幼苗的存活与生长有着显著影响,特别是沙埋深度超过其株高后,其存活率和高生长受到严重抑制,但和非沙生植物相比,差巴嘎蒿幼苗具有很强的耐沙埋能力,即使沙埋深度达到其株高的200%时仍有部分幼苗存活。随着沙埋深度的增加,差巴嘎蒿幼苗叶片含水量没有显著变化,但过氧化物歧化酶活力降低,过氧化物酶活性增强,过氧化氢酶活性变化不明显,脯氨酸含量增加,可溶性糖含量下降,丙二醛含量下降,膜透性增强。和水分、盐分胁迫不同,沙埋并未造成差巴嘎蒿幼苗的水分亏缺,沙埋胁迫下差巴嘎蒿幼苗死亡率增加、生长受到抑制的主要原因是沙埋导致植物光合面积下降,沙埋叶片无法进行正常呼吸和部分幼苗无法破土生长,但沙埋胁迫下脯氨酸含量的和过氧化物酶活性增强分别在渗透调节和保护细胞膜免受损伤中起到了关键作用。

Ecological adaptation and physiological response of Artemisia halodendron seedling to sand burial

There is a great deal of literatures on the effects of sand burial upon the survival and growth of desert plants, but the physiological and ecological adaption of desert plants to sand burial have as yet rarely been studied. Artemisia halodendron is widely distributed in the semiarid deserts of China and is a dominant species in semi-moving dune vegetation. In order to understand the ecological and physiological adaptation of prammophytes to sand burial,,changes of survival rate, plant height, biomass, osmotic regulation substances, protective enzymes and membrane permeability of A. halodendron in different sand burial depths were studies during 2010-2011 in the Horqin Sand Land of Inner Mongolia. The experiment included ten burial treatments: buried to 0% (CK, no burial), 25% (A), 50% (B), 75% (C), 100% (D), 125% (E), 150% (F), 175% (G) and 200% (H) and 225%(I) of seedling height. The results showed that 1) A. halodendron had a stronger ability to withstand sand burial stress, with some plants still surviving even if buried to a depth reaching 200% of the seedling heights. Although seedling growth was inhibited significantly once the depth of sand burial reached 50% of seedling height, seedling survive did not decrease significantly until the burial depth exceeded 100% of seedling height; 2) MDA content was significantly lower in the partial sand burial treatments compared to CK, but membrane permeability did not increase significantly. After being subjected to complete sand burial, MDA content was still lower in most the treatments compared to CK, while membrane permeability increased significantly. Sand burial did not produce water stress in the seedlings, a major mechanism causing decreased MDA content is that the darkness, hypoxia and low temperature inhibit production of oxygen free radicals and membrane lipid peroxidation; 3) Compared with CK, SOD activity was significantly lower in all sand burial treatments except for treatments D and H, POD activity was higher in all sand burial treatments except treatment D, and CAT activity showed no significant changes with any of the sand burial treatments except for being elevated in treatments C and D. In general, POD activity increased when the activities of SOD and CAT decreased, and SOD and CAT activities increased when POD activity decreased. MDA content had a positive correlation with SOD and POD and a negative correlation with CAT. These results suggested that although there was a complementary interplay among the three enzymes, POD played a central role and SOD and CAT played supporting roles in scavenging active oxygen and minimizing cell membrane damage; 4) When subjected to partial burial with sand, proline content showed no significant changes and the soluble sugar content decreased significantly compared to CK. After sand burial exceeded the seedling height, proline content increased significantly; although soluble sugar content increased, the difference from CK did not reach a significant level. The results suggested that when subjected to the severe stress of sand burial, proline plays a major role and soluble sugar fails to play an effective role in the osmotic adjustment process.