紫花针茅生殖器官形态的变异及其与环境因子的关系

Variations of reproductive organs morphology of Stipa purpurea and relationship with climate on the Qinghai-Tibetan Plateau

紫花针茅(Stipa purpurea)是青藏高原分布面积最广的植物之一,对高原环境具有广泛的适应性。该植物具有的锥形繁殖体(包括种子和附属结构),是其适应环境的主要特征之一。为揭示该植物对高原环境的适应性表现,本研究对不同纬度的20个紫花针茅种群繁殖体的形态特征及其与环境的关系进行比较研究。结果表明,1)种长的变化幅度为0.692~1.255 cm,种宽的变化幅度为0.392~0.713 mm,芒长的变化幅度为2.394~8.736cm,种子重的变化幅度为0.678~1.560 mg。芒长和种子重具有较高的种群间变异系数。种子重与种长呈极显著正相关关系(P【0.01),和芒长呈显著正相关关系(P【0.05);种长、种宽、芒长相互之间均呈极显著正相关关系。2)种长、种子重与等效纬度均呈显著正相关关系,与年均降水量均呈显著负相关关系;种长与年均温呈现出凸型变异的关系。3)20个种群依据繁殖体特征进行聚类分析可分为3组,聚类结果与地理分布基本一致。

As constructive species of alpine meadow and steppe,Stipa purpurea adapt to different climate conditions and is one of the most widely distributed plants on the Qinghai-Tibetan Plateau. Trypanophorous diaspora( including seeds and accessory organs) owned by S. purpurea is one of the most important factors for the plant to adapt to harsh environment. To illustrate the adaptive characteristics of this plant to the plateau environments,trypanophorous diasporas of 20 S. purpurea populations along a latitudinal gradient on the Qinghai-Tibetan Plateau were collected. Morphology characteristics of these diasporas from different populations were measured and their relationship with environmental conditions were also analysis in the present paper. The results showed that seed length,seed width,awn length and seed mass ranged from 0. 692 ~ 1. 255 cm,0. 392 ~ 0. 713 mm,2. 394 ~ 8. 736 cm and 0.678 ~ 1. 560 mg,respectively. There were high values of coefficient of variability( CV) among populations in awn length and seed mass. Seed mass positively correlated with seed length and awn length. Seed length,seed width and awn length were positively correlated with each other. Seed length and seed mass increased significantly with equivalent latitude,but decreased with annual precipitation. Seed length displayed humped-shape relationships with mean annual air temperature. These 20 S. purpurea populations clustered into 3 groups according to these tested characteristics of trypanophorous diaspora,which consistent with geographic distributions of these populations.