自然界中种皮不透水而不能吸胀发芽的种子称为硬实。硬实这种休眠形式对植物界种的延续和传播极为有利,它不仅能在较长的时期内保持种子的活力,而且能在种子成熟、收获以后的不同时期内,由于环境条件的作用改变种皮透性,使不同的个体先后获得发芽能力。但也有不利的方面,如紫云英、苜蓿、田青等未经处理的种子经常不发芽,播种后发生严重的 In nature, the seed coat is impermeable to water and sprouting and germination is called hardwood. Hardly dormant forms of the continuum and dissemination of plant species is extremely beneficial, it not only in a long period of time to maintain the vitality of seeds, but also in the seed maturity, harvesting after different periods, due to environmental conditions change species Permeability, so that different individuals have access to germination ability. But there are also adverse aspects, such as asparagus, alfalfa, Tian Qing and other untreated seeds often do not germinate, serious after sowing