Seed drying is a crucial step in seed processing, directly influencing the vitality and storage life of seeds. The core point is to safely, evenly and efficiently reduce the moisture content of seeds without damaging their physiological activity.
The following are the six key points for seed drying, which are divided into principles, process control, and precautions:
I. Core Principle: The “High to Low” Temperature Control Principle
This is the most crucial principle for seed drying, based on the physiological characteristics of seeds.
Early stage (high moisture content): When the moisture content of seeds is relatively high (e.g., >18%), their life activities are vigorous, and water is prone to evaporation. They can tolerate relatively high temperatures (but within a safe range). Higher hot air temperatures can quickly remove a large amount of free water, thereby enhancing efficiency.
Late stage (low moisture content): When the moisture content of seeds drops to a relatively low level (such as <13%), the seed cells transition from a “swimming state” to a “colloidal state”, becoming highly sensitive to heat. At this point, the drying temperature must be reduced and gentle drying methods employed; otherwise, it is very likely to cause protein denaturation, enzyme deactivation, and damage to the embryo, commonly known as “cracking” or “scorching”, which results in the loss of seed viability.