ABSTRACT
In the soil, seeds are exposed to various factors including temperature, moisture, gas composition, and light, which may act independently or collectively to regulate germination and subsequent seedling growth. The main factors responsible for the composition of the gaseous phase at the level of the seedbed are the structural characteristics of the soil, the diffusion and solubility coefficients of gases, as well as oxygen uptake and carbon dioxide and ethylene release by living organisms. Seeds are incapable of germinating under unfavorable environmental conditions, such as too low or high temperature depending on the species, or too low an oxygen concentration. In apple embryos, cold stratification usually required for breaking primary dormancy can be replaced by a two- or three-week treatment with pure nitrogen, and this effect of anoxia increases with temperature. Seed germination and seed dormancy are multifactorial phenomena the regulation of which involves various internal and external factors that usually act simultaneously.
