小叶锦鸡儿幼苗对沙埋的生态适应和生理响应

以中国半干旱地区固定、半固定沙地分布最广泛的灌木种之一小叶锦鸡儿(Caragana microphylla)为对象,于2010～2011年在内蒙古科尔沁沙地测定了不同深度沙埋下其幼苗的存活率、株高、渗透调节物质含量、保护酶活性和膜透性变化,探讨小叶锦鸡儿对沙埋的生理响应特征。结果显示:(1)与对照相比,当沙埋深度为小叶锦鸡儿幼苗株高的25%～75%时,存活率差异不显著;当沙埋深度为50%～75%时其存活率增加,但株高明显下降,沙埋对其生长具有抑制作用;当沙埋达到其株高100%时幼苗全部死亡。(2)不同沙埋深度对小叶锦鸡儿幼苗叶片细胞膜透性无显著影响,对沙埋深度为其株高25%时,叶片含水量增加,MDA含量下降,POD活性增强,细胞膜未受到伤害;沙埋深度为其株高50%～75%时,叶片含水量下降,MDA含量增加,但SOD和POD对细胞膜起到了协同保护作用,细胞膜也未受到损伤;沙埋深度为株高25%～75%情况下,细胞膜未受到损伤,可溶性糖和脯氨酸含量变化不明显。研究认为:小叶锦鸡儿幼苗只能耐受部分沙埋,完全沙埋则会导致其幼苗全部死亡,沙埋胁迫下可溶性糖和脯氨酸等渗透调节物质含量反应迟缓可能是其耐沙埋能力较弱的主要生理原因之一。

Ecological Adaptation and Physiological Response of Caragana microphylla Seedling to Sand Burial

Caragana microphylla is one of the most widely distributed shrubs in fixed and semi-fixed sand land,semi-arid areas of northern China.Change on survival rate,plant height,osmotic regulation substances,protective enzymes and membrane permeability of C.microphylla in different sand burial depths was measured and its eco-adaption and physiological response to sand burial was studies during 2010-2011 in the Horqin Sand Land of Inner Mongolia to understand the mechanism of C.microphylla to adapt sand land environment.The results showed that:(1)The ability of C.microphylla seedlings to resist sand burial was weaker,the seedlings all died when depth of sand burial was 100% plant height.Changes of seedling survival rate were not significant at sand burial depth of 25% and 75% plant height.The plant height decreased significantly when sand burial depth was plant height 50%~75%,which show that the moderate and heavy sand burial cause the inhibition of C.microphylla growth.(2)At the buried depth of the height 25%,leaf water content increased,MDA content decreased,POD activity increased,the cell membrane was not harmed.Although the plant leaf water content decreased,MDA content increased.Due to the synergistic effects of SOD and POD to protect the cell membrane,the cell membrane is not damaged when the buried depth of the plant height was 50% and 75%.At the buried depth of the height 25%~75%,changes in the soluble sugar and proline were not significant because the sand burial stress is light and the cell membrane has not been damaged.It was concluded that C.microphylla seedlings can only withstands the partial burial by sand,all the seedlings died when subjected to completely sand burial.It was one of the main physiological mechanisms that soluble sugar and proline failed to play an effective role in osmotic adjustment process with a increase of sand burial stress.