准噶尔荒漠3种藜科植物种子异型性的生态适应机制

Seed heteromorphism means production of seeds that differ in shape, size, colour and/or external structure, as well as in dispersal, dormancy, germination and seedling growth, and often heteromorphic seeds are from different positions on the same plant. It is considered to be an adaptation to spatially and temporally heterogeneous environments. Since it is a unique way by which plants adapt to their environment, seed polymorphism has significant value to understanding mechanisms of adaptation to habitat and evolution of plant life-history strategies. This item will systematically investigate plant of Chenopodiaceae in the Junggar Basin to collect the plant species with seed heheromorphism. We select 3 species (Suaeda acuminata (L.) Pall., Salsola affinis C. A. Mey., Ceratocarpus arenarius L.) to study ecology adaptation mechanisms of heteromorphic seeds. The study content includes heteromorphic seeds morphological structure and germination behavior, the difference of life-history characters (growth, physiology and reproduction characters) of offspring from heteromorphic seeds and the effect on life-history characters from environment. This item will help to understand ecology adaptation strategy of Chenopodiaceae in the Junggar Basin in life-history characters, but also clarify adaptation mechanisms to desert. The study conclusion will enrich the theory of life-history evolution and has practice significance on conservation of desert vegetation.

种子异型性作为植物对极端环境的一种独特适应方式，在研究植物的生活史进化和生态适应机制方面具有重要价值。本项目以分布于新疆准噶尔荒漠具有种子异型性的3种藜科植物- - 高碱蓬、紫翅猪毛菜和角果藜为研究对象，拟通过进一步调查，研究该地区藜科具有异型种子植物的种类，异型种子的形态结构和萌发行为，异型种子萌生植株的生活史性状（形态生长特征、生理特征、生殖发育特征等）差异以及环境对这些性状的影响，阐明准噶尔荒漠藜科具异型种子植物在生活史特征上表现出来的适应对策，揭示具异型种子植物适应荒漠环境的机制。研究结果将丰富和发展种子多型性和生活史进化理论的研究成果，并对准噶尔荒漠植被的保育具有重要的实践意义。

以分布于新疆准噶尔荒漠具有种子异型性的藜科植物(紫翅猪毛菜为例)为研究对象，研究异型种子的形态结构和萌发行为，生活史性状以及环境对这些性状的影响，表明：.紫翅猪毛菜产生A型种子（绿色横生种子）和B型种子（绿色直立种子）C型种子（黄色直立种子）；野榆钱菠菜有的黑色和褐色2种形态种子；异苞滨藜产生2种类型种子——黑色和褐色。绿色种子和褐色种子的萌发率都在80%以上；黄色种子和黑色种子的萌发率小于50%，低温层积、划破果皮和种皮处理能够有效地加速和提高种子的萌发，表明黄色和黑色种子处于非深度休眠状态。.紫翅猪毛菜种群有大小不同个体。伴随个体大小的变化，紫翅猪毛菜三种类型种子在植株上的比例不同，绿色横生种子（A型）随个体的增大所占比例逐渐增多，由0.43%增加到51.07%；绿色直立种子（B型）随个体的增大所占比例逐渐减少，由65.80%减少到18.06%；黄色直立种子（C型）随个体的变化所占比例没有显著变化，约为30～35%。当植物体干重超过1g后，总繁殖分配趋于稳定。随着植株个体的增大，A型繁殖体的繁殖分配显著增加，B型繁殖体的繁殖分配显著减少；C型繁殖体的繁殖分配没有显著的变化。.以紫翅猪毛菜为代表的藜科植物产生具有不同萌发策略和散布策略的种子，以及不同类型繁殖体的权衡和种子输出的灵活性形成了混合生殖对策，使植物在高度不稳定的环境中具有竞争优势，减小了环境的时空变化对植株生殖成功的影响，允许其在高度不稳定的环境中成功定居。