 |
 |
Corn Testing Services
SGS offers quick, professional, and diagnostic service to seed companies from over 43 different states and several countries.
- Standard Germination Test (Warm)
- Tray Cold Test
- Saturated Cold Test
- Herbicide Tolerance Tests
- Bt Corn – ELISA
- Electrophoresis / Isozymes
- Quick ColdSM and Quick Saturated ColdSM
- Waxy Corn Purities
- Accelerated Aging Tests
- Tetrazolium Test
- Mechanical Purity and Noxious Weed Seed Examinations
- Conductivity Tests
- Fast Green
- Shake-out Service
- PCR Servcies
- Corn Germination and Cold Remarks Reference Form
- Automatic Retesting
Saturated Cold Test
Saturated Cold Tests utilize subirrigation to provide a saturated soil/towel media (100% WHC) condition throughout the test. Cold period is seven days at 10C followed by a 64 hour 25C warm period.
This test is commonly used as the primary cold test method or on certain grade sizes and when questionable quality is indicated by standard germination and/or tray cold tests. Please submit at least 250 grams of seed.
Herbicide Tolerance Tests
Herbicide Tolerance Tests are offered for Clearfield® (ALS), Roundup Ready® and Liberty® corn. A 400 seed sample is tested for seven days with tolerant and non-tolerant check samples.
If the sample tests below the minimum requirements for herbicide tolerance, an additional 400 seeds are tested at no charge. Submit at least 1,200 seeds for these tests.
Electrophoresis / Isozymes
Isozyme testing can be used to determine Genetic Purity and to verify a hybrid’s identity. Hybrid purity or variety characterization may assist a seed producer in developing and marketing their seed.
Hybrid purity - Typically 100 seedlings are tested. Female selfs, Offtypes, Variants and purity percentages are determined.
Hybrid Verification – 10 seedlings are tested and compared to the expected hybrid pattern.
Quick ColdSM and Quick Saturated ColdSM
The Quick ColdSM and Quick Saturated ColdSM tests were developed to simulate the Tray Cold and Saturated Cold tests, respectively. What makes these tests appealing is that the results are available several days quicker. Many lab and field studies were conducted over a period of two years to develop relationship data. We encourage quality assurance departments to evaluate these tests and compare them to their current cold test methods. Please contact us for more information.
|
|
|
|
Waxy Corn Purities Waxy Corn Purities are conducted on an 800 seed sample. Please submit at least 250 grams of seed. |
|
|
|
|
Tetrazolium Test Tetrazolium Test is a quick viability test to estimate standard germination percentages. This test can be useful when frost damage occurs. |
Fast Green
Fast Green is a pericarp (seed coat) damage assessment test. Please submit at least 250 grams. This can be completed within two days.
Shake-out Service
We perform shake-outs and treating as a service to our clients. You can submit a 20-25 pound sample. Please specify sizes and tests requested.
PCR Servcies
We offer PCR testing for both GMO detection and Event Identification for a wide variety of transgenic events. Qualitative and Real-Time PCR are available.
Corn Germination and Cold Remarks Reference Form
When germination tests are evaluated the seedling abnormalities, fungal species (warm test) and seedling growth (cold test) are described. Below are listed the most commonly observed problems and possible causes.
Physical / Mechanical Abnormalities
| Observed Symptom | Possible Cause |
| Shredded leaves (SL) | Impacts to shoot and coleoptile |
| Insufficient roots (IR) | Impacts to radicle and mesocotyl |
| Stunted shoot growth (SS) | Damage within or below growing point |
| Peeling pericarp (PP) | Physical damage related to freeze injury |
| Frost damage (FD) | Physical damage related to freeze injury |
| Lacks primary root (LP) | Impacts to radicle and mesocotyl |
| Leaves bent/protruding from base of coleoptile (LB) | Impacts to shoot and coleoptile |
Physiological Abnormalities
| Observed Symptom | Possible Cause |
| Plumule < 1/2 coleoptile (PC) | Freeze injury or aged/weak seed |
| Swollen mesocotyl (SM) | Freeze injury or aged seed (shoot and root are also stunted) |
Pathological Abnormalities
| Observed Symptom | Possible Cause |
| Decayed seedling (DS) | Fungal infection by Fusarium,Penicillium spp. |
| Rhizopus spp. (RH) | Sugar leakage from aged or damaged seed--rated by the amount of Rhizopus mycelium present on the growing media. T - trace, very few colonies. |
Fungi Observed
| Species | Possible Cause |
| Fusarium spp. (FU) and Diplodia spp. (DI) | Field Fungus - ear rots. |
| Aspergillus flavus (AF) & Aspergillius niger (AN) | Storage fungus - high seed moisture. |
| Penicillium spp. (PE) | Storage Fungus - high seed moisture |
| Alternaria (AL) | Field Fungus |
FU, AF, AN, AL and PE are reported only when 2% or more of sample is dead or infected.
Cold Test (Tray/CCP method) Remarks
- Slow growth (SG) Slower growth rate than normal as compared to check samples.
- Uniformity Varies (UV) The percentage of seedlings on a tray that are less than 1/3 of the average normal seedling height.
- Extended Uniformity Varies (EUV) UV after sample has been extended for a 2 day period.
Fast Green Abnormalities
| Observed Symptom | Description | Consequence or Cause |
| Protruding Plumule (PPL) | Plumule extends outward from normal surface of seed. | Succeptable to mechanical damage during, harvesting, conditioning and handling |
| Peeling Pericarp (PP) | Portions of seed coat detached or peeling seed surface. | Physical damage, possibly related to freeze injury. |
| Black Layer Exposed (BE) | Tips of seed broken off, exposing black layer. | Mechanical damage caused by harvesting/shelling/shelling. |
| Cracked Seed (CK) | Whole seeds with cracks/damage | Mechanical damage caused by harvesting/handling |
| Mechanical Damage (MD) | Split seeds and/or half seeds | Harvest or handling damage to seed. |
| Silkcut Damage (SKC) | Exposed starch | Seed growing into silks, forming cuts in pericarp. |
Automatic Retesting
We offer customers an automatic retesting option when ‘apparent’ seed quality issues occur. This retest will provide additional information on the seed lot to facilitate seed quality decisions. Currently, this service is offered on corn, soybeans, sorghum and cotton.
You, the customer, choose the thresholds that would trigger the auto-retest and MWSS sets these thresholds up for your account in our computer system. For example: if you want corn samples to be auto-retested when the warm germination falls between 79% and 94%, the thresholds for a warm germ test would be set at 80<=Germ<=93. Samples falling into this range receive an automatic retest. Retest threshold ranges can be applied to most germination-based tests and can be easily adjusted if your needs change.
There is no charge for setting up auto-retest thresholds and once auto-retesting is in place; your samples will be retested within 24 hours thus saving valuable time in your decision-making process. Retests are billed to your account at the same rate as the regular tests.
