The pre-sowing low temperature treatment of seeds is known as . A: scarification B: electrophoresis C: vernalizaion D: abscission

离层（abscission layer）即脱落层，将受病部位与健康组织隔断，阻止了物质的运输和病菌的扩散，受病组织逐渐的皱缩、死亡，随同病原菌一起脱落。