Has your seed been rain-damaged?
It is important to get your seeds graded – particularly if they have been stored for a while or have been damaged.
Due to the immense rainfall over the 2022-23 season, seed grading is especially important as the weather may have caused significant damage to your seeds.
Weather-damaged seeds generally have decreased roots, inconsistent seedling emergence and shorter and thinner coleoptiles. If the seeds have been exposed to a large extent of weather damage, the seedlings can then have a reduced leaf area and slow root growth. This results in them having a decreased chance of accessing important soil nutrients and moisture leading to lower germination and crop yields.
Dr Greg Rebetzke, CSIRO’s Agriculture and Food chief research scientist, details the importance of grading your seed in wet harvest years to protect your crops from damage including fully sprouted, discoloured or diseased grain. He explains that “what is less obvious is grain that has started the germination process but then dried down, often resulting in partially-wrinkled or cracked grains that have compromised seed quality”.
Seed grading ensures that these damaged seeds are extracted and only the best are left to be sowed. Dr Rebetzke also suggests that “a basic seed germination and vigour test will determine if the seed is suitable for planting”.
So, what is seed grading?
Seed grading is a process that helps to sort and improve the quality of seeds. It involves separating seeds by size, shape, and other characteristics. The sorting process removes any damaged or defective seeds making sure you’re left with a high-quality product suitable for planting. Graded seed has a higher crop health, vigour, and yield. Grading also helps to maintain the quality of the seed from one season to the next.
The process is carried out using specialised equipment with screens and air extraction, designed to sort seeds based on their size and shape, and suck out all dust, chaff and lighter grains. The sizing sieves filter out harmful materials that are larger or smaller than the grain itself – leaving only the healthy, more vigorous seed. Seed that is consistent in size and shape will generally germinate and grow more evenly.
What are the benefits of grading your seed?
Dr Rebetzke, states that “vigorous seedlings are an inexpensive way to help control weeds, increase water-use efficiency and grow more grain”.
Grading your seed is crucial in ensuring you get the best possible crop. Some benefits of seed grading are:
- Getting a larger seed: Only using the larger seed gives a better chance of producing strong seedlings and increasing the crop yield.
- Higher vigour: Larger seeds also have a higher vigour which gives the seed a better chance of germination, emergence from the soil and strong healthy seedlings that grow faster.
- Removing negative elements: Through the removal of foreign materials, you are giving your seed a better chance at growth without having to compete with foreign seed, weeds, dirt, and other debris.
- Less affected by adverse conditions: Poorer conditions, such as issues with soil or weather have a much higher impact on lower quality seed than that with a higher vigour.
Summary
To ensure you are using the highest quality seed to maintain a healthy, vigorous crop, seed grading is an important step to follow. This is especially necessary for the 2023 season as the large amounts of rainfall received last year has damaged seeds and not grading seed or not using properly graded seed could leave you with a less than satisfactory crop in the upcoming season.
