Properly stored seeds can live for years. Improperly stored seeds can’t. Moisture is typically the factor that makes the difference. It’s common to link moisture content with seed viability, but water activity is a better way to measure and monitor moisture in seeds.
Here are three reasons why:
-Use water activity to find the moisture sweet spot
There is a moisture “sweet spot” for seeds, dry enough to minimize enzymatic activity, yet wet enough to prevent desiccation. When you try to define that sweet spot using moisture content, the band is narrow, making it hard to accurately measure. The corresponding water activity range is much wider, giving you much greater precision in defining and measuring the moisture sweet spot to guarantee the viability of your seeds.
-Use water activity to predict fungal growth
Enzymatic activity and desiccation are not the only factors that damage seeds. Fungal growth is also a significant problem. Water activity measurements accurately predict which microbes and fungi can grow in a porous material. By measuring the water activity of your seeds, you can predict whether or not specific classes of fungi will grow on the seeds.
-Use water activity to make priming easier
Seed priming is most effectively accomplished by monitoring and controlling the water activity of the seeds. Subject seeds to specific water activities to start germination, and then dry them to lower water activities to stop germination. These seeds will be more viable for the next attempt at germination. The precise control afforded by water activity increases successful germination rates.