Kent J. Bradford, Peetambar Dahal and Brenda Dawson of Horticulture CRSP have responded at length to the comments made by Robin Probert and Fiona Hay on their factsheet promoting the use of Zeolite as a possible alternative to silica gel to dry seeds. Many thanks to them all for taking the time to engage in this debate. Please read the rebuttal in full, it’s very detailed and will be of great interest to anyone who keeps seed healthy for a living. However, if I were to be forced to pick a couple of quotes as take-home messages, they would be these:
At present, drying beads are probably economical only for high-value vegetable seeds or germplasm repositories, but there are simple ways to utilize drying beads in forced-air drying systems that could be adaptable to larger seed or commodity volumes, such as in combination with large plastic grain bags that are coming into use.
…
We believe that drying beads should be of particular interest for seed banks in developing countries where power outages make continuous operation of refrigeration and dehumidification equipment problematic. We expect that drying beads combined with hermetic containers could largely replace dehumidification of large storage rooms in seed banks. Enclosing a small quantity of beads in foil packet or glass jar with a seed sample would be a great solution for local seed banks that may not have the drying equipment that Robin mentioned.
Which are not altogether dissimilar conclusions to the ones we originally came to, but as I say, read the whole thing and make up your own mind. It would be great to hear from anyone out there that has experience of using these drying beads, whether in a genebank or other context. If you do, or know anyone who does, leave a comment below.