Flax TIPS: Seed Quality for 2017: Why, how and what to do now?
Low Test Weight
According to the Canadian Grain Commission 2016 preliminary report, 86% of flaxseed samples graded CW No.1, down from 98% in 2015. The CGC has commented that primary grade factors contributing to lower grade are low test weight and high percentage of inseparables (e.g. weed seeds). Test weight is one of many factors that affect the grade of flax. What constitutes a low test weight and how does it affect seed grade? The table below shows minimum test weight thresholds for each flaxseed grade.
Minimum Test Weight for Canada Western Flaxseed Grades
|Grade||Minimum Test Weight (kg/hl)||Minimum Test Weight (lb/bu*)|
|CW No. 1||65||52|
|CW No. 2||62||49.7|
|CW No. 3||No Minimum||N/A|
*Represents an Avery bushel
There have been few studies on what causes low test weight, however heat stress and disease (e.g. Septoria linicola a.k.a. pasmo) have been associated with lower seed weight.
Canadian flax varieties are semi dehiscent, which means that the boll is open at the top and the five segments that form each boll separate slightly along the margins. This characteristic allows seeds to remain in the boll, but still threshed relatively easily. It also means that moisture and microbes can enter, sometimes causing seed weathering. Prolonged periods of moisture, like what many areas on the Prairies saw in 2016, increase the likelihood of weathering which can cause dark or scabby seeds.
The conditions in 2016 were conducive to many crop diseases, which can show up on the seed after harvest. A fungal/ disease scan by any reputable seed lab can provide you with information on the type and proportion of infected seeds in the sample. Unfortunately we do not have established thresholds for tolerable levels of each disease on flaxseed. That said, common sense says lower is better (less than 10%), and if there is presence of a disease that may increase the chance of that particular disease showing up later in the season (e.g. pasmo). Monitoring and management plans should take this into consideration.
Germination vs. Vigour Tests
A germination test must be done before seed can be sold in Canada, and represents the proportion of germinating seeds under ideal conditions. A vigour test can be a valuable addition to your seed quality testing, because it is a measure of how seed will perform under stress. According to Shari Lafreniere (2020 Seed Labs), Manitoba samples have had germination numbers in the mid to high 80’s with corresponding vigour tests in the 70% range. By comparison, Alberta samples to have been quite a bit lower. In Saskatchewan, 2016/17 samples submitted to Discovery Seed Labs have been fairly consistent with last year’s values, with average germination in the high 80’s and vigour around 75%. However, to date there have been 75% fewer samples than in 2015.
Managing for Reduced Seed Quality
Seeding Rates Based on Plant Population
If seed quality, e.g. low test weight, disease, low germination, are a concern calculating a seeding rate based on a desired plant population becomes very important to establishing a healthy stand. For maximum yield, farmers should target a plant population of 30 – 40 plants/ft2. Typical seedling survival of flax is approximately 50 – 60%.
Seeding Rate (lb/acre)
% Expected seedling survival x 10
Plant stands above 40 plants/ft2 do not necessarily increase yield and may actually predispose the crop to disease and lodging.
Yellow seeded varieties should be seeded at a slightly higher seeding rate (approximately 10%), particularly if seed treatment is not used.
Seed treatments can be used to protect germinating seedlings from seed and soil borne diseases, improve seedling survival and can be particularly beneficial when dealing with reduced seed quality or diseased seed. Seed treatments can also protect seeds that are germinating in poor soil conditions. However, seed treatments have limited protection period, and cannot rescue shriveled or broken seeds. Good agronomy (e.g. seed bed conditions, reducing seed cracking at harvest) and crop rotation are also important tools for managing soil borne diseases.
There are three seed treatments registered on flax:
- Vitaflo®-280 (UAP): seed rot, root rot and seedling blight caused by Rhizoctonia solani and Fusarium spp.
- Insure® Pulse (BASF): seed rot, root rot and seedling blight caused by Rhizoctonia solani and Fusarium spp.
INTEGO™ Solo (Valent): seed rot/pre-emergence damping-off caused by Pythium spp.
Industry research has shown an improvement in emergence when using a seed treatment on flax but there is no evidence to date indicating a yield advantage. New research at the Indian Head Agricultural Research Foundation, funded by SaskFlax and BASF, is underway evaluating seed treatments and seeding rates on emergence and yield.
Flax has typically been considered difficult to treat due to the mucilage on the seed coat. Seed treatments are formulated to penetrate the seed coat. Ensure uniform mixing to prevent clumping and do not add water. If using high rates, treated seed will benefit from allowing to dry in a truck box.
Interested in trying a seed treatment? Start with a small amount to see how it works for you.
Bin-run vs. Certified Seed?
- Traits. Using certified seed ensures the genetic purity of the traits of that particular variety. If seed is saved year to year it can eventually dilute the sought-after characteristics of that variety.
- Weeds. Using certified seed ensures strict standards for the kind and amount of weed seed that can be in each bag of certified seed.
- Germination. If you are using bin-run seed, a vigour test from a qualified seed lab can provide a better indication of in-field germination than a germination test alone.
- Storage. Storage and heating of flaxseed can cause deterioration of the germination potential, so testing prior to seeding is important.
- Pre-harvest / Desiccants. Do not use seed that has been treated with glyphosate pre-harvest due to reduce germination. Certified seed is not permitted its use. In contrast, Reglone® (diquat) has not been shown to negatively affect seed germination.
- Re-constituted Varieties. Use re-constituted certified flax varieties or certified seed of varieties developed by the CDC, AAFC or CPS which were released in 2014. If the seed in the bin that is older than 2014 be absolutely certain before you seed flax that samples test negative for CDC Triffid.
For more information:
Canada Grain Commission Flax Harvest Report: https://www.grainscanada.gc.ca/flax-lin/hqfm-mqrl-eng.htm
Canadian Flaxseed Grading Factors: https://www.grainscanada.gc.ca/oggg-gocg/11/oggg-gocg-11d-eng.htm
Vigour Tests: http://www.2020seedlabs.ca/what-vigour-test
Calculating a Seeding Rate: https://www.agric.gov.ab.ca/app19/calc/crop/otherseedcalculator.jsp
Understanding soil-borne disease: https://www.saskatchewan.ca/business/agriculture-natural-resources-and-industry/agribusiness-farmers-and-ranchers/crops-and-irrigation/crop-protection/disease/seed-borne-diseases-of-cereal-crops/seed-testing
Find a list of accredited seed labs here: https://csi-ics.com/accredited-labs
More on seed treatments in flax: http://www.grainews.ca/2016/09/02/getting-covered-treating-flax-seed-2
More on the re-constituted seed program: https://flaxcouncil.ca/growing-flax/re-constituted-seed-program/