FROM THE GARDEN
As we make plans to plant summer gardens we often start by sowing seed that has been saved from previous years. But how disappointing it is when seeds never come up. Before using old seed, first test the seed for viability to determine if seeds are capable of germinating. Following are two easy ways to test for seed viability.
Germination testing: This method reveals the percentage of seeds in a given lot that are capable of germznating, which can then be used to predict the proportion of seed that is viable.
Dampen a paper towel, squeezing out any dripping water; place at least 20 seeds on the damp towel; gently fold or roll towel; place in a zip-lock plastic bag; seal; move bag to a warm location out of direct light; check daily by gently unfolding the towel. Germination of some types of seed may commence within one day; others take longer to germinate. Most germination tests terminate after 15 days. A seed is considered viable and to have germinated when the radicle, the first root, pokes out from the seed coat and begins to elongate, an indication of the potential to produce a healthy seedling.
Float testing: While this method does not actually allow for the germination of seed, this is routinely used to test for viability of large seeds like okra and beans.
Place clean seed in a glass filled one-fourth full of warm water. Let sit undisturbed for 15 minutes up to several hours. Viable seeds are filled with living (but dormant) embryos, which are heavier than nonviable seeds with shriveled or dead embryos; the heavier and presumed viable seed will sink. Nonviable seeds, called “light” seeds in the trade, will float. To eliminate nonviable seeds from your inventory, simply float them off and into the trash, hence the name the float test.
Calculate the percent seed germination in the test by counting the number of seed that germinated, dividing the number germinated by total seeds tested. For example, if 14 of 20 seeds germinated, the percent germination would be 70 percent, so 70 percent of the seeds are viable.
Calculate viability of seeds in the float test by recording numbers of floaters and sinkers, dividing the number of sinkers by total tested. If 20 seeds were tested and 18 sank, the percent viability would be 90 percent.
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