盐生植物种子萌发对环境的适应对策

盐生环境是一种严峻的胁迫环境,对植物的生长、发育、繁殖等生活史的各阶段都产生着重要的影响。盐生植物是生长在盐渍土壤上的一类天然植物区系,它们在长期的进化过程中形成了一系列适应盐生生境的特殊生存策略。一般情况下,盐生植物种子对环境的适应能力,是植物对盐生环境适应性的重要体现;而植物发育早期对盐度的适应能力又是决定物种分布和群落组成的关键因素。在对国内外相关文献进行分析归纳的基础上,从盐分对种子萌发的影响机理及植物种子萌发对盐生环境的适应对策两个方面综述了植物种子休眠萌发与盐生环境的关系。

The adaptive strategies of halophyte seed germination

Saline habitat is one kind of the most stressful habitats. The plant growth, development, reproduction and all the life cycles may be affected in this environment. Halophyte is a natural flora that inhabits the salt environments. In the long term of evolution, halophytes have formed a lot of special strategies for survival and occurring in this habitat. During the plant life cycle, seeds of most plant species have the highest resistance to extreme environmental stresses, whereas seedlings are most susceptible. The period of germination and establishment is the most critical stage in the life cycle, which is a crucial factor in determining the species distribution and community components. The survival of plants under salt conditions is mainly associated with the germination mechanisms that ensure seed germination and seedling development at the favorable time and place. The osmotic effect and the specific ion toxicity are the two main factors that cause germination inhibition. However, there isn't consensus on which one is more important than the other. It may be a combination of the two factors and varies with the species and the types of salts. The interaction between salinity and temperature during the germination period also control halophyte seed germination and determine the seedlings which can establish successfully in saline habitats. Halophytes can endure high salinity. Even though the salinity is too high for seed germination, seeds can remain viable until the stress is relieved. An important characteristic of halophyte seeds is their ability to remain dormant at high salinity and germinate later when salinity is reduced, while glycophyte seeds can not survive at the same salinity. The soil seed bank of halophytes provides a significant means by which the population information is able to be reserved even in the stressful environments, avoiding the local extinction of some specific populations. Seed polymorphism is an essential mechanism for parent plants to respond to various environmental conditions and allocate their nutrition to different seed morphs, providing more opportunities for the plant population establishing. Some halophytes germinate at the special time and space, this characteristic ensure that they complete the early development stage in favorable environments. The different reproductive strategies make halophytes have more opportunities to survive in the saline habitats. In this paper we summarized the relationships between the saline habitat and halophyte seed germination in two parts: (1) The influence of salinity on seed germination. (2) The adaptive Strategies of halophyte seed germination.