Seed Production and Storage

• Seeds for propagation are generally grown in special production fields by farmers who specialize in seed production.
• The longevity of seed storage is determined by seed moisture content and temperature.
• As a general rule, seed storage life decreases by half for every 5 degrees C rise in temperature from 0 to 50 degrees C, or every 1% increase in moisture content from 5 to 14%.
• Another helpful rule is that the % relative humidity + the temperature in degrees F should be kept below 100 during seed storage.
• Seeds are hygroscopic and can gain or lose moisture from the air. If seeds are stored at moisture contents greater than 18%, damage can occur from heat buildup due to high respiration. Between 10 and 18%, fungi and mold can grow on seeds. Between 9 and 14% moisture content, insects may be active.
• For open storage, starchy seeds should be stored at less than 12% moisture content, while oily seeds such as watermelon should be maintained at a moisture content of less than 9%. Sealed storage requires moisture content from 6 to 8%. In some seeds, storage at less than 4% moisture content can be damaged due to auto-oxidation of lipids. Beans are more susceptible to mechanical damage when dried to less than 10% moisture content. As a general rule, the best moisture content for seed storage is about 5%. For storage at home, temperatures should be low but not below freezing. In some germplasm repositories, some seeds are now stored in liquid nitrogen, but seed moisture must be low and carefully controlled to protect the seeds from damage. Seeds stored properly in liquid nitrogen should last indefinitely.
• To protect genetic resources, the USDA maintains collections of diverse cultivars for many of the important crops grown in the United States at the National Center for Genetic Resources Preservation (NCGRP) – Pictures >> in Fort Collins, Colorado, formerly called the National Seed Storage Laboratory.