狮牙草状风毛菊果期资源分配对海拔的响应

Response of resource allocation of Saussurea leontodontoides during its fruiting stage to the elevation

植物资源分配是目前植物生态学研究的热点问题,主要集中在性分配和繁殖分配两个方面。该研究以分布在青藏高原的狮牙草状风毛菊(Saussurealeontodontoides)作为研究材料,研究了6个海拔高度上果期植株的繁殖特征及资源分配的差异,并用异速模型分析了繁殖性状及资源分配与个体大小的关系。结果显示:(1)狮牙草状风毛菊的个体大小、繁殖器官生物量、营养器官生物量、种子数和营养分配均与海拔存在极显著负相关关系,百粒质量和繁殖分配与海拔存在极显著正相关关系。(2)在不同海拔高度下,百粒质量、种子数、繁殖器官生物量及营养分配与植株个体大小呈正相关关系;繁殖分配与植株个体大小呈负相关关系;而营养器官生物量与植株个体大小呈极显著正相关关系。这表明海拔和个体大小对狮牙草状风毛菊的繁殖对策有不同程度的影响,狮牙草状风毛菊通过增加繁殖部分的生物量和百粒质量来适应高海拔的胁迫环境。

Aims Our objective is to study the differences between the reproduction characteristics and resource allocation of Saussurea leontodontoides in the fruiting stage across six levels of the elevation gradient, and analyze the relationship between the above two parameters and individual size of S. leontodontoides. Methods The study site is located in the northeastern margin of the Qingzang Plateau. The collection and investigation were carried out on the fruiting individuals of S. leontodontoides which were distributed in an elevation range of 3 200–4 540 m. 40 complete individuals were randomly collected from each level of the elevation. The number of seeds in each capitulum was counted, then the biomass was measured after drying at 80 ℃ in the oven. The differences between the reproduction characteristics and resource allocation of S. leontodontoides at different levels of the elevation gradient were analyzed by ANOVA. The relationship between the reproduction characteristics with individual size, resource allocation with individual size at different levels of the elevation gradient was analyzed by the allometric model. Important findings Our results showed that: (1) The individual size, reproductive organ biomass, vegetative organ biomass, seed number and vegetative allocation were negatively correlated with elevation;the hundred grain mass and reproductive allocation were positively correlated with elevation. (2) Along the elevation gradient, the hundred grain mass, the seed number, the reproductive organs biomass and the vegetative allocation were positively correlated with individual size;reproductive allocation was negatively related to individual size;and vegetative organ biomass and individual size were significantly positively correlated. This indicates that the elevation and individual size had different effects on the reproductive strategy of S. leontodontoides. Our study suggests that S. leontodontoides adapted to the high-elevation stress environment by increasing the reproductive organs biomass and the hundred grain mass.