To dry or not to dry: consider temperature when saving seeds

Beans on palm (Nicholas Githiri/Pexels)


Saving seeds for the next cropping season has long been a way of life for many farmers. This practice resulted in the creation of heirloom crop varieties that have been passed down through generations. For many farmers, saving and storing seeds is a practical way of saving money. Instead of buying seeds every year, saving seeds allows them to be self-sufficient in growing their own crops. 

However, not all seeds can be stored for a long time. Whether you are planning to store excess purchased seeds, saving seeds for the next planting season, or planning to plant the seeds at a later time, it is important to know the different classifications of seeds based on their tolerance to drying and low temperature.

Orthodox Seeds

Orthodox seeds can tolerate dry (5-7% moisture) and freezing conditions without losing viability. They can be stored for a long time when kept in an environment with low moisture content and a freezing temperature. Most orthodox seeds are smaller compared to the other seed types. These include grain crops, legumes, corn, rice, cabbage, onion, and tomatoes.

Recalcitrant seeds

Recalcitrant seeds are short-lived seeds. They can only tolerate a moisture content of 20 – 30% and cannot withstand freezing conditions. They should never be dried in the sun. Examples of recalcitrant crops are most fruit-bearing trees such as mango, jackfruit, coconut, avocado, sapote, and mangosteen. Some of these crops can only be stored for several weeks.

Intermediate seeds

Intermediate seeds are slightly tolerant to drying (9-10% moisture content) but can not survive freezing conditions. Examples of these crops are coffee, papaya, and citruses. They can be stored only for a few months before they lose their viability.

The seed viability, or the ability of the seeds to germinate after their storage, naturally decreases through time, but it can be prolonged by properly storing and handling the seeds. In the seed industry, they use a guideline called “Harrington’s Rule” to determine the best storage conditions for seeds. According to Harrington’s Rule of seed storage, for each 1% decrease in moisture content, the storage life of the seed is doubled. And for every 5.6°C decrease in storage temperature, the storage life of the seed will also double. However, it is still limited to the capability of the seed to tolerate drying and low temperature, whether they are orthodox, recalcitrant, or intermediate seeds.

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