What type of containers allow for extended germination test limits?

Hermetically sealed containers are designed to be airtight, preventing the ingress of moisture and other environmental factors that can affect seed viability during germination testing. This controlled environment allows for a more stable testing condition, thus extending the limits for germination tests. When seeds are placed in these containers, they maintain consistent humidity and temperature levels, which are crucial for accurate germination results.

In contrast, other types of containers, such as plastic bags, cardboard boxes, and glass jars, may not provide the same level of protection from external conditions. For instance, plastic bags can allow some air exchange and might not effectively prevent moisture loss or gain, while cardboard boxes are permeable and thus potentially expose seeds to varying humidity levels. Glass jars can be better than plastic bags or cardboard but may still allow for temperature fluctuations or moisture condensation that can interfere with the germination process. Thus, hermetically sealed containers are specifically advantageous for extending germination test limits.