不同生境条件四合木(Tetraena mongolica)内源激素季节变化及种群差异

The seasonal change of endogenous phytohormone and differentiation of populations in Tetraena mongolica in different habitats

四合木(Tetraena mongolicaMaxim)是西鄂尔多斯地区特有的单种属古地中海残遗植物。选择了分布区内有代表性的低山、台地、丘陵、高平原、倾斜平原5个典型生境的四合木种群为研究对象。对不同生境四合木种群密度、盖度、年龄结构和根际土壤理化性质进行研究,运用酶联免疫吸附法对四合木叶片内源激素(ABA、IAA、GA3、ZT)季节变化和生境间差异性进行探讨。结果表明:(1)不同生境四合木种群密度、盖度、年龄结构存在显著差异,且低山、台地、丘陵种群所处生境有利于幼苗更新,其密度和盖度均显著大于高平原和倾斜平原种群;(2)四合木根际土壤有机质含量、土壤含水量、营养元素(N、P、K)、微量元素(Fe、Mn、Cu、Zn、Mo、B)含量均较低,pH偏高,体现出贫瘠碱性化的荒漠土壤特点。运用数理统计将5个样地土壤理化性质进行聚类分析,分为两类:低山、台地、丘陵种群为一类(A类),高平原、倾斜平原为一类(B类)。方差分析表明:A类样地土壤营养元素(N、P、K)和微量元素(全Fe、Mn、Zn、B、Mo与有效量)、土壤有机质含量及土壤含水量都显著高于B类,而pH值显著低于B类。(3)5个四合木种群ABA和GA3含量均表现为:8月份>6月份>5月份;IAA的含量和ZT的含量均表现为:6月份>8月份>5月份。方差分析表明:5月份IAA含量表现为在A类样地>B类样地,8月份ABA含量和GA3含量表现为在A类样地>B类样地。(4)四合木分布区存在较大的生境异质性,在其长期适应过程中,生境条件差异导致了种群在生理生态方面的分化。四合木种群密度、盖度、年龄结构以及土壤养分、水分和内源激素在生境间存在着差异。

Tetraena mongolica Maxim, an ancient specie in its own genus and well-adapted to drought environments, is a xerophytic shrublet in the Western Erdos, Inner Mongolia. Five populations of T. mongolica in the habitats of upland, hill tableland, high plain and terrace were selected as our research objects. Through analyze the soil physical and chemical characters, drawing the charts of density, coverage, age-class structures of T. mongolica populations in the different habitats, to investigate the change of endogenous phytohormone （ABA, IAA, ZT, GA3 ） in the leaf of T. mongolica populations with season and habitats by means of Enzyme Linked lrnrnunosorhent Assay （ EL1 SA）. The results showed （ 1 ） There was a significant difference in density, coverage and age-class structures of T. mongolica populations in different habitats. The habitats of Upland, hill and tableland population were fit for seedlings rebirthing, and the density and coverage in these three populations were significantly higher than that of high plain and terrace populations. （2） The content of organic matter, nutritional elements （N,P,K） ,micro-element（Fe,Mn,Cu,Zn,Mo,B） was very low, but the pH was high. This embodied the bad condition of barren soil and alkalization in desert. The physical and chemical index of soil in T. mongolica were cluster analyzed and T. mongolica population in five habitats were classified into two groups： upland, hill and tableland populations （ group A） and high plain and terrace populations （ group B）. The content of organic matter, pH, nutritional elements （ N, P, K）, micro- elements （ Fe, Mn, Cu, Zn, Mo, B ） in the group A was significantly higher than that in group B. （3） The change trend of ABA and GA3 in the five populations were distinct and regulative in the whole growthing season,i, g. August 〉 June 〉 May. Similarly, The content of IAA and ZT embodys distinct regulative changes, i. g. June 〉 August 〉 May. The content of IAA in May, ABA and GA3 in August in group A were significantly higher than that in group B. （4） There was large heterogeneous habitat in the distribution region of T. mongolica, the difference of habitats resulted in the differentiation of population in physio-ecological in the long adaptability process, resulted the differences in density, population coverage, age-class structures, soil-nutrient, soil water content and endogenous phytohormone of T. mongolica populations in different habitats.