Dormancy Mechanism and Breaking Methods for Hard Seeds
硬实种子休眠的机制和解除方法

Hardseedness is a naturally occurring phenomenon for many plants, especially leguminous species. Dormancy for hard seeds is caused by impermeability to water and gas and mechanical constraint of the seed coat. All of the genetic factors, maternal environment, storage conditions,collecting methods and the degree of maturity, moisture content, size, shape and colour of seeds can affect hardseed percentage. The methods for breaking dormancy in hard seeds are generally classified into physical, chemical and biological treatments, which hasten germination by improving seed coat permeability, gas exchange, and water entrance and relieve mechanical constraints. The physical methods include mechanical scarification, low and high temperature, hydration-dehydration, irradiation, high pressure and other physical treatments, and the chemical ones include acid scarification, alkali solution soaking and other organic chemical treatments. Dormancy in hard seeds benefits spatiotemporal distribution of seed germination and is of great significance for preserving germplasm.