Source of Life and Duration of Use of Crop Seeds: Seed Technology Category: Technical Articles Updated Time: 2008-10-29 16:23:09 Read 68 times
Li Shengxiang (Hangzhou Xiaoshan Seed Management Station)
Seeds, like all living organisms, continue to carry out life processes within their cells. When a seed reaches full maturity, it separates from the parent plant and becomes an independent entity. At this point, it enters a state of dormancy, appearing inactive on the surface. However, the embryo inside remains physiologically active, though at a very low level. The life of a seed is closely tied to its storage conditions and the external environment. Poor storage can significantly reduce viability, while optimal conditions help maintain it for longer periods.
The term "seed life" generally refers to the maximum period during which a seed can retain its viability under specific storage conditions after maturation. In agricultural practices, it's crucial to implement effective measures to maximize the lifespan of crop seeds, ensuring they meet production requirements. As a planting material, seeds must have strong vitality, not only germinating properly but also doing so uniformly. Therefore, the useful life of seeds in agriculture is closely related to their overall lifespan. However, there is no universal agreement on how these two concepts align.
In our region, the lifespan of cereal seeds typically ranges from 1 to 3 years. Seeds used in the following year are often still viable under normal conditions. In general, the useful life of seeds isn't very long. For example, the lifespan of milk vetch and cotton seeds is much longer than that of rice and wheat. With refrigeration available at home, small quantities of vegetables can be stored for over three years, maintaining their viability. However, in actual agricultural production, few seeds are used beyond three years.
This is because, after a certain storage period, physiological changes occur in the embryonic cells. Although viability may not be completely lost, the original metabolic activities begin to decline. When sown, such seeds might germinate, but the resulting seedlings tend to be weak, stunted, or deformed, affecting both quality and yield. Therefore, the useful life of seeds shouldn't be judged solely by whether they can germinate. It requires careful observation and comparison based on long-term agricultural practices. A reliable range for different crops and varieties should be determined according to local climate conditions.
Currently, the standard for assessing the age of agricultural seeds is still based on the germination rate. This is because a seed’s vigor after a certain storage period is largely reflected through its germination rate. It is generally believed that although germination rates decrease with time, as long as they remain above 50%, more than half of the seeds in the batch are still viable. These seeds can still be used when new seeds are insufficiently available.
In southern China, where temperatures are high, the lifespan of crop seeds is relatively short, and the useful life is close to the total lifespan. In contrast, in the dry and cold regions of the north, the lifespan of seeds is significantly extended, creating a larger gap between useful life and total lifespan.