川西风毛菊果期资源分配对海拔的响应

The response of Saussurea dzeurensis fruiting resource allocation to differences in elevation

以分布于青藏高原东缘的川西风毛菊为试验材料,研究了其不同海拔高度16个居群的果期资源分配。结果显示:1)随着海拔的升高,个体大小、繁殖器官生物量、营养器官生物量、根系质量、茎叶质量以及每株植物种子总数量均不断减小,但种子百粒重不断增加;2)繁殖分配和根系分配与海拔呈正相关关系,营养分配和茎叶分配与海拔呈负相关关系;3)果期繁殖分配和营养分配、根系分配和茎叶分配以及种子数量与百粒重之间均存在资源分配上的权衡。研究结论:1)海拔作为外界因子对川西风毛菊果期各生物量及资源分配有显著的影响;2)随着海拔的升高,川西风毛菊通过增加繁殖分配,根系分配以及种子百粒重来适应胁迫环境,提高自身的适合度。

Saussurea dzeurensis is a perennial herb belonging to the family Asteraceae, and is widely distributed across the eastern Qinghai-Tibet Plateau. The environmental factors affected by elevation have significant effects on the resource allocation of plants. The study of resource allocation is an important part of understanding the environmental factors that contribute to population differences and species evolution. In this study, our objective is to investigate the fruiting resource allocation of Saussurea dzeurensis at different elevations, ranging from 2750 to 3700 m above sea level. During the fruiting phase of September 2014, we collected samples from 16 populations of S. dzeurensis at 8 elevations （2750, 2900, 3050, 3200, 3300, 3500, 3600, and 3700 m）. We randomly harvested 10 individuals from each population, and measured their reproductive organ, vegetative organ, root-system, and stem-leaf biomass. Then, we selected 10 capitula randomly from each population, and counted the seed number and 100-grain weight of each capitulum. All experimental data were analyzed using the statistical analysis software SPSS 20.0, and Excel 2003. The results showed that：1） as elevation increased, the size, reproductive organ biomass, vegetative organ biomass, root-system mass, stem-leaf mass, and seed number of each individual plant decreased continuously, while the hundred grain weight increased continuously; 2） reproductive allocation and root system allocation were positively correlated with elevation, while vegetative allocation and stem-leaf allocation were negatively correlated with elevation; 3） there was a trade-off between resource allocation during reproductive allocation and vegetative allocation, and between root system allocation and stem-leaf allocation. Conclusion：1） as the independent variable, elevation had a significant impact on the biomass and fruiting resource allocation of S. dzeurensis; 2） when resources are limited, S. dzeurensis balanced the resource input into each of its structures; 3） as elevation increased, S. dzeurensis individuals adapted to increased environmental stress and improved their fitness by increasing their reproductive allocation, root system allocation, and hundred grain weight.