Some producers may be anxious this year to find out the germination percent of the wheat they harvest, to see if it will make suitable seed. If they do a home germination test too soon after harvest, they may be shocked at the low germination percent – unless the test is done correctly. That’s because wheat has a post-harvest dormancy requirement (some varieties more so than others). Even high-quality seed will not germinate at its maximum capacity right after harvest in most cases. This post-harvest dormancy is important to help decrease the chances of pre-harvest sprouting in case harvest is delayed due to weather conditions or other reasons.
To get around that, for the first several weeks after harvest it’s important to make sure the wheat is pre-chilled before taking a germination test. Any reputable seed lab will do that on a routine basis. Producers testing their seed at home should also pre-chill the wheat by planting it and putting it in the refrigerator at about 40 degrees for 5 days. If the seed is not pre-chilled, producers should wait a month and a half after harvest before testing for germination.
There is some difference among varieties regarding how long their post-harvest dormancy requirement is – so much so that some varieties are more prone to pre-harvest sprouting. Hard white wheats with poor sprouting tolerance, for example, have almost no summer dormancy requirement. They will germinate almost as soon as the seed is harvested. Other varieties have a relatively long summer dormancy requirement, and may not germinate well for five or six weeks after harvest unless the seed is pre-chilled. By Labor Day, all varieties will have lost their summer dormancy and should germinate unless the seed is defective in some way.
If there is any question about the viability of the seed, it is well worth the cost to have the seed tested for germination by a certified seed laboratory. This is especially true in areas where there was freeze damage, severe drought or heat stresses during grain filling, a rain delay at harvest, or wheat head scab.
Home testing: Doing it correctly
If producers want to test their seed for germination at home, it needs to be done correctly to be of value.
- Place two moistened paper towels (on top of each other) on a flat surface. The towels should not have free water in them.
- Arrange fifty (50) seeds on the towels leaving approximately an inch border around the edges.
- Place two more moistened towels over the seeds.
- Make a ½ to ¾ inch fold at the bottom of the four paper towels. This will keep the seed from falling out.
- Starting on one side, loosely roll the paper towels toward the other side (like rolling up a rug) and place a rubber band around the roll(s).
Place the roll in a plastic bag. Seal, but not completely, so as to keep moisture in but still allow some air into the bag.
For newly harvested seed:
- Place the bag upright in the refrigerator for 5 days and then remove and place upright at room temperature for an additional 5 to 7 days.
- Remove the sample from the bag and unroll the towels.
- Count and record the number of healthy seedlings (adequate root and shoot development and NOT overtaken by disease.)
For carryover seed, or after September 1:
- Place the bag upright at room temperature for 5 to 7 days.
- Remove the sample from the bag and unroll the towels.
- Count and record the number of healthy seedlings (adequate root and shoot development and NOT overtaken by disease).
To calculate the germination percentage: divide the number of healthy seedlings by the number of seeds tested and multiply by 100.
Example: 42 healthy seedlings X 100 = 84% germination
50 seeds tested
This may be repeated more times for each sample in order to obtain more accurate results, testing up to 400 seed. If the seed will be treated with a fungicide seed treatment prior to planting, the test should be performed after the seed treatment is applied because it can increase the germination percentage.
Testing by a certified lab
Having your seed professionally tested for germination is always a good practice, but with the severe drought and heat stress on the wheat crop in many areas this year, it is highly recommended.
Source : ksu.edu