Germination Capacity

A germination test places a counted sample of seeds under prescribed conditions of substrate, moisture, temperature, and duration, then counts the proportion that produce a normal seedling — one with the structures needed to develop into a viable plant under favourable conditions. Seedlings that fail to emerge, or that emerge but are abnormal, damaged, or decayed, are not counted as normal even though a seed produced some growth.

Because the prescribed conditions are standardised and designed to be favourable, the test is reproducible between laboratories and over time, which is what makes it usable as a basis for seed certification and for malting contracts. That same standardisation is also its principal limitation, addressed below.

A real seedbed rarely offers the near-ideal moisture, temperature, and soil conditions a germination test provides. Cold soil, excess or deficient moisture, surface crusting, seedling diseases, and mechanical impedance in the field all reduce the proportion of sown seeds that actually establish as plants, none of which the laboratory test is designed to capture. The result is that laboratory germination capacity routinely overstates what the same seedlot will achieve when sown, and the size of that gap is exactly what vigour testing is designed to estimate — vigour tests deliberately impose stress conditions that a standard germination test does not.

Germination capacity is decisive for two distinct buyers and irrelevant to a third handling the same physical commodity. A seed buyer needs the lot to establish a crop, so germination capacity — alongside vigour — is central to whether the lot is fit for purpose at all. A maltster needs the grain to germinate on demand as the first controlled step of malting, so germination capacity is equally central there, for a different reason. A miller or a feed compounder, by contrast, has no use for germination at all: grain destined for flour, oil, or feed is valued for composition and processing performance, not for its ability to grow.

Germination capacity is sensitive to how the seed was dried and handled. Excessive drying temperature can damage the embryo without leaving a visible mark on the kernel, and mechanical impact during harvesting, conveying, or cleaning can crack or bruise seed in ways that reduce germination even when the kernel looks intact. This is one reason seed and malting grain are commonly dried at lower temperatures than grain destined for feed.

Germination capacity also declines over time in storage, at a rate governed chiefly by the moisture content and temperature the seed is held at rather than by a fixed calendar interval — seed held cool and dry retains germination capacity far longer than the same seed held warm and moist. Because of this, a germination test result carries an implicit expiry and is normally re-tested before a critical use such as sowing.