It’s that time of year when producers are booking their winter wheat seed. To order enough seed, you’ll need to know how much is needed for the acres you have planned – and you can go one step further than using the ‘rule of thumb’ of 2 to 2.5 bushels per acre. To calculate seeding rate and how much seed is needed, the following critical pieces of information are required.
Target Plant Stand. For winter wheat, producers should be aiming for a target plant stand of 30 plants per square foot in the fall. In the spring, it is hoped established plant stand will be 25 plants per square foot to maximize yield potential and increase crop competitiveness.
Thousand Kernel Weight (TKW). TKW is what it sounds like – the average weight in grams of a 1000 kernels. There is variability between winter wheat varieties commonly grown in Manitoba. If looking at registration data, varieties such as Emerson or CDC Falcon had TKWs around 29 to 30 grams, while varieties such as AAC Gateway had a TKW of 32 grams and AAC Elevate had a larger seed size of 36 grams per 1000 kernels. Remember TKW can change yearly based on growing conditions – just because your chosen winter wheat variety was 32 grams in 2015 does not mean that it will be the same in 2016.
Expected Seedling Survival Rate. Expected seedling survival rate is the percent germination less an amount for seedling mortality.
The percent germination will of course be available from your seed retailer if you are booking certified seed. If considering using farm-saved seed, also be sure to test – and make sure a test is done after seed cleaning and at an accredited lab (and no…..kernels on a wet paper towel on a windowsill is not a germination test!!). Since most germination tests are relatively inexpensive, it is a small price to pay. And while you are having percent germination done, get the TKW as well.
The other factor of expected seedling survival rate is seedling mortality, i.e. what percent of viable seed will germinate but not produce a plant. I wrote a Crop Chatter post on April 26th asking readers if they’d considered their seedling mortality. The focus was on spring cereals, but the same principles apply to winter wheat as well. Seedling mortality can vary greatly from year to year, and field to field. For spring cereals, seedling mortality rates can range from 5 to 20%. However, for winter wheat a seedling mortality rate on the higher end of the range should be used to take into account winter survival.
The Western Winter Wheat Initiative (www.growwinterwheat.ca) suggests using an expected seedling survival rate of 70%, which takes into account germination, emergence rate and the impact of winter survival.
So obtaining the above information may not be as easy as using a bushel per acre seeding rate. However, taking those extra steps will help ensure you are hitting your target plant stand – one of the first steps in setting your 2017 winter wheat crop up for success.
Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture
For more information on winter wheat production, visit Manitoba Agriculture’s website at http://www.gov.mb.ca/agriculture/crops/production/winter-wheat.html