青藏高原几种植物种子萌发与幼苗建植的局部适应性及其母本环境效应

Study of local adaptation is of fundamental importance in understanding adaptation evolution, shift, and extinction risks of plant population especially under the rapid global climate change background. Also, understanding plant local adaptation plays a key role in selecting seed source for restoration project.This study combines common garden experiment and reciprocal sowing experiments to explore the local adaptation of seed germination and seedling establishment of different population of six common grassland species distributed along the attitudinal gradient in Tibetan Plateau. This study mainly focus on: 1) effect of maternal environmental effect and local adaptation on the home-site advantage of seed germination phenotype and seedling establishment under various field condition; 2)the key phenotype traits of seed germination and seedling establishment contributing to local adaptation and its diversification of several common species from Tibetan Plateau and its potential influencing factor; 3) effect of seed storage and dormancy breaking treatment on seed germination and seedling establishment, and its potential effect on evaluation of local adaptation. Based on this, we aimed to clarify the effect of maternal environment and seed treatment on evaluation of local adaptation of seed germination and seedling establishment, and provide scientific evidence for building a explicit evaluation system for local adaptation. Further, we aimed to understand the key phenotype traits of local adaptation of seed germination and seedling establishment of several common species from Tibetan Plateau and its underlying driving force, and thus provide scientific data supporting for grassland management and restoration in Tibetan Plateau ecosystem.

沿环境梯度研究植物居群的局部适应性对深入了解全球气候变化背景下物种的适应进化、预测其迁移与局部灭绝风险以及生态恢复中种源的选择具有重要意义。本项目以青藏高原不同海拔梯度分布的6种常见草地植物为材料，结合同质园种植与交互移植试验，主要研究：1）母本环境效应与局部适应性在青藏高原常见草地植物不同居群种子萌发与幼苗建植本土适应优势形成中的作用；2）青藏高原常见草地植物种子萌发与幼苗建植局部适应性形成的关键表型性状、种间多样性及其影响因素；3）种子贮藏或者休眠破除处理对种子萌发表型与幼苗建植的影响及其对局部适应性评价的作用。基于上述研究，阐明母本环境与种子处理对局部适应性评价的影响，为建立科学的局部适应性评价体系提供依据；明确青藏高原常见草地植物种子萌发与幼苗建植关键表型性状局部适应性形成的驱动力，为青藏高原草地生态系统的科学管理与生态恢复提供科学依据。

沿海拔梯度研究植物居群的局部适应性，对于了解物种进化的趋同与分异机制，特别是在全球气候变化条件下，预测物种的进化、迁移趋势与灭绝风险等具有重要意义。本研究以广泛分布于青藏高原的垂穗披碱草、椭圆叶花锚和喉毛花种子为材料，结合同质园种植与交互移植试验，研究了上述物种不同居群种子萌发、出苗、生长和繁殖等对母本环境和子代环境的响应，分析了种子贮藏、母本环境等对居群局部适应性评价的影响，取得以下主要研究成果：1）同质园种植减小了居群间种子萌发温度参数如萌发基础温度（Tb）和积温值（θT(50)）的分异，表明母本环境可通过影响种子萌发参数进而改变种群在苗期及后期的适应性；2）层积温度、水分和时间均显著影响椭圆叶花锚种子的休眠释放，种子休眠释放对层积温度和水分的需求在居群间存在差异，如较之于高海拔的椭圆叶花锚居群，低海拔居群的种子休眠释放对温度增加和水分降低更为敏感，表明不同居群植物种子休眠释放对所处海拔的温度和水分环境存在局部适应性，这一适应性可能在一定程度上影响其出苗时间及后期生长；3）种子经过贮藏不仅改变了种子的萌发表型、出苗和生长繁殖特性，也改变了居群间原有的分异，进而影响局部适应性的有效评价，因此，局部适应性的评价应根据研究目标充分评估种子贮藏可能带来的影响；4）不同海拔梯度植物居群在种子萌发与出苗阶段是否具有局部适应性因物种而异，如低海拔的椭圆叶花锚居群在两个同质园均有较高的适合度，而低海拔的垂穗披碱草居群在低海拔同质园适合度较高，表明在生态恢复中应充分考虑种子的来源。上述研究阐明了母本环境及种子贮藏对种子萌发表型与幼苗建植局部适应性评价的影响，为正确认识和评价种子萌发表型与幼苗建植的局部适应性以及建立相应的评价技术体系提供了科学依据。有关不同植物居群局部适应性的结果为生态恢复工程选择合适的种源，确保草地恢复生态系统的可持续性奠定了科学基础，为认识气候变化背景下植物种群的动态变化提供了科学依据。