不同梭梭种群同化枝的解剖结构特征及其与生态因子的关系分析

该研究于中国西北干旱区按自然降水梯度从东向西选择6个梭梭种群,取其当年生同化枝作为试验材料,采用石蜡切片法,应用光学显微技术测定同化枝9项解剖结构指标,分析不同生境下梭梭同化枝解剖结构的变异特点以及与生态因子的关系,为干旱区生态环境保护和梭梭资源的保护与利用提供理论依据。结果表明:(1)干旱荒漠环境的梭梭同化枝解剖结构具有连续的栅栏组织、花环结构、含晶细胞和贮水组织等结构特征,但其表皮细胞、角质层厚度、气孔位置和气下室与旱生植物结构有差异,主要表现为表皮细胞和角质层较薄,气孔半下陷且气下室不发达。(2)梭梭同化枝各种群间的9项解剖结构指标都存在显著差异,其中变异系数较大的是维管束个数/直径和角质层厚度,变异系数分别为22.78%和15.20%;相关分析表明:同化枝直径、栅栏细胞切向长、贮水组织厚度和维管柱直径均与经度、纬度、海拔、一月均温、七月均温、年均温、年降水量和年相对湿度等8个生态因子有不同程度的相关性,其中与经度、海拔、七月均温和年平均相对湿度显著相关。(3)6个梭梭种群通过聚类分析可分为两大类,分析结果与所观察到的生境类型、地理分布的划分基本一致;随着自然降水量自东向西减少,梭梭的抗旱性相应逐渐增强。

Relationship between Anatomical Differences and Ecological Factors of the Assimilating Shoots of Haloxylon ammodendron

The annual assimilating shoots of 6 Haloxylon ammodendron species were selected as experimental materials,which were gotten from arid region of northwest China according to precipitation gradient which is from east to west.9 anatomical structures were measured.We analyzed the relationship between anatomical differences and ecological factors of the assimilating shoots of H.ammodendron,to provide theoretical basis for the protection and utilization of the ecological environment and H.ammodendron resources in arid areas of China.Results showed that:(1)the anatomical structure of the assimilating shoots of H.ammodendron in the arid desert environment with continuous wreath of palisade tissue,structure,crystal cell and water storage organization structure,but the epidermis cells,cutin layer thickness,hole position under the gas chamber difference with xerophyte structure,mainly displays in the epidermal cells and corneous layer is thinner,porosity nuder half wubsidence and gas chamber is not developed.(2)9 anatomical structures of the assimilating shoots of each characteristic of 6 H.ammodendron species have significant differences by variance analysis.The variability coefficients are greater in the number of vascular bundle and cuticle thickness with the values of 22.78% and 15.20%,respectively;Correlation analysis showed that each index has different degree of correlation with eight ecological factors,which are longitude,latitude,altitude,average temperature in January and July,annual average temperature,annual precipitation and annual average relative humidity.The diameter of assimilating shoots thickness,palisade cell cut to length,water storage tissue thickness and vascular cylinder diameter have different degrees of correlation with eight ecological factors.(3)6 populations of H.ammodendron could be divided into 2 categories by cluster analysis.The results of cluster analysis were identical with the habitat types and geographical distribution of H.ammodendron;as fewer natural rainfall from east to west,the drought resistance of H.ammodendron gradually strengthened.