Quality Assurance Testing Strategies

QUALITY ASSURANCE TESTING STRATEGIES FOR CORN SEED

What are the standard tests that should be the basis to your quality assurance and quality improvement program?

Sheller-run samples or pre-conditioned samples

Standard Germination (warm) – based on 400 seed or a herbicide trait germination based on 400 seed is recommended to establish the maximum germination potential of the seed. Some companies will perform Pericarp Damage (fast green) test after shelling to establish the level of mechanical damage. The warm germination test is a good measure of mechanical damage and can identify fungal species and sugar leakage.

Cold Tests – Tray colds and saturated colds are the recommended vigor tests for corn. Both of these methods have imbibitional chilling and respiratory stress. The saturated cold is a high stress test that will separate hybrids on innate quality and will give a wider separation of seed lots. The minimum quality value is 70% for saturated colds. Tray colds are widely used and have minimum quality values of 85-90%.

Trait Confirmation – When a trait is from the female parent, 90 and/or a 400 seed sample from the bulk lot is checked for insecticide and herbicide trait percentages, respectively. When the trait comes from the male parent, 90 and/or 400 seed sample from each expected grade size is checked for insecticide and herbicide trait percentages, respectively. When the VTTM Roundup Ready/ Rootworm trait is involved, the insecticide trait (RW) can be tested at the 30 seed level and meet the licensing requirements for testing.

Hybrid Purity and Fertility – Electrophoresis purity checks of 100 seed on round grade sizes (SR and MR) is the recommended first step. Winter grow outs are recommended for fertility checks or a five day laboratory testing using PCR technology is available at Mid-West Seed Services when time is a limiting factor.

Adventitious Presence – We recommend checking bulk seed for trait and conventional hybrids for Adventitious Presence (AP1200 is the recommended test and utilizes 1200 seed for herbicide traits and 2400 seed for insecticide traits).

Conditioned Seed Lots

Standard Germination (warm) – based on 400 seed and a Purity/Noxious seed examination on 500 grams is the official tests needed for labeling a seed lot. Tests should be conducted in accordance with Association of Official Seed Analysts (AOSA), since regulatory officials will check seed using this same set of rules.

Cold Testing – check lots using tray and/or saturated colds, minimum quality values of 85% and 70%, respectively.

Trait Confirmation – Herbicide trait confirmation on a 200 seed sample per seed size is recommended to assure no contamination has occurred. Insecticide trait confirmation requires a 30 seed test per seed size for each respective event. If trait testing was not conducted on the sheller run seed, a 400 seed herbicide and/or a 90 seed insecticide test is required for each respective grade size marketed.

Hybrid Verify – a 10 seed electrophoresis analysis of the seed lot is recommended to confirm hybrid pedigree. Hybrid purity for South American production should be checked using a 100 seed electrophoresis test.

Adventitious Presence – recheck conventional graded lots with AP1200, organic seed lots should use AP2400.

SAI loading – loading rates of seed applied insecticides should be checked.

Carry Over Seed Lots – warm germ (400 seed) and tray or saturated cold are recommended.

Kalyn Brix-Davis - DNA-Protein Laboratory Manager