AOSA germination testing is crop specific. Seeds differ in dormancy, seed-coat permeability, oxygen demand, light response, temperature response, susceptibility to decay, and seedling structure. The method must therefore be selected by botanical kind rather than by convenience.
Approved substrates serve different biological and analytical needs
AOSA methods may use between-paper systems, top of blotters, covered paper containers, sand, pleated paper, or another approved substrate specified for the crop. The substrate controls seed contact, water availability, oxygen, root development, seedling separation, and the analyst's ability to evaluate structures.
The substrate must be non-toxic and prepared to the moisture condition required by the crop. Cucumber, for example, is kept on the drier side to reduce avoidable decay. Onion is sensitive to toxic paper and excess moisture. Large seed may require sand or a different physical arrangement to allow normal development.
Constant and alternating temperatures trigger different responses
Some crops use a constant temperature program. Others use alternating temperatures, such as approximately 16 hours at 20 C and 8 hours at 30 C. Alternation can improve the response of crops whose germination is tied to day and night temperature cycles.
The chamber record captures actual temperatures, not only the setpoint. Deviations can change speed, dormancy response, decay pressure, and seedling development.
Light is part of the method for selected crops
Some seed kinds germinate rapidly without a light requirement. Others respond to prescribed light, often during the warm portion of an alternating temperature cycle. Zinnia method cards may call for light during the warm phase. Borage uses a light period within its controlled setup. Dormancy options for selected crops may also combine light with another authorized treatment.
Pretreatments address dormancy and seed-coat barriers
Prechilling, scarification, potassium nitrate, light, and other treatments are used only when the crop method prescribes or permits them. They are not general remedies for every slow test. The analyst first confirms the seed kind and then applies the treatment that belongs to that method.
Prechill can help overcome physiological dormancy in selected crops. Scarification can improve water entry where a hard seed coat is the barrier. Potassium nitrate and light can support germination in crops with specific dormancy responses.
Examples from AONSK method cards
| Crop | Method controls | Count schedule |
|---|---|---|
| Capsicum spp., sweet pepper | Approved paper substrata or covered paper system; 20 to 30 C alternating; dormancy treatment when prescribed. | First count around day 10; final count around day 14. |
| Cucumis sativus, cucumber | Paper substrata or sand; 20 to 30 C alternating; substrate maintained on the drier side. | First count around day 3; final count around day 7. |
| Allium cepa, onion | Between-paper, approved paper substrate, or pleated paper; 20 C constant; non-toxic media. | First count around day 6; final count around day 12. |
| Zinnia elegans, zinnia | Top of blotters or approved paper substrate; 20 to 30 C alternating; light during the warm phase. | First count around day 3; final count around day 7. |
| Brassica oleracea var. viridis, collard | Paper, blotters, or covered paper system; 20 to 30 C alternating; dormancy treatment when needed. | First count around day 3; final count around day 10. |
| Borago officinalis, borage | Covered paper system; 20 C constant; at least eight hours of light daily. | Final count around day 10. |
The method is part of the result
A germination percentage has meaning because the seed kind, sample, substrate, temperature, light, treatments, count timing, and seedling rules are controlled. Change the method, and the biological response can change with it.
That is why AONSK builds method selection before chamber scheduling and why each test follows a crop-specific card.
