Factors influencing longevity

So far, we have explored how scientists investigate longevity and viability, and considered some of the factors that can affect these qualities. Back in the 20th century, a vast body of evidence was built up to support the idea that the lower the storage temperature, and the lower the moisture content of the seeds, the longer the period of viability for seeds in storage. Other scientists during the last century conducted experiments to investigate the gaseous environment: they built up sufficient evidence for us to assert that for most species, the higher the oxygen pressure, the shorter the period of viability.

More recent experiments confirm that time spent in storage is an important predictor of how a seed lot will perform in germination tests. This issue has become more pressing as genebanks, and their collections, come of age in the 21st century. Meanwhile, discoveries from priming experiments have given us a more nuanced understanding of the impact of moisture content. These experiments have suggested ways in which manipulation of the moisture content of seeds may improve viability. There are other influences: seeds may be immature, dormant, quiescent or empty. You will learn more about these influences later in the course.

Figure 14 summarises the full range of conditions of the storage environment, which can affect the viability and longevity of seeds. You might like to keep a high quality version of the image, so you can refer back to it in future. To do this, first click the 'Maximise' link below the image: to download, right click or control click once the image has opened.

Maximise

Figure 14: Factors influencing seed lot viability

Now that we have considered all the factors that may influence seed longevity, it is time to return to the Genebank Standards for storage, and consider how they might be modified by genebanks, depending on species and context.