A 45-year-old mung bean discovery exposes a hidden threat to the world’s doomsday seed banks — frozen crops may not survive as long as scientists once believed

The world’s seed banks are often described as emergency vaults for humanity’s food supply. Hidden in secure facilities, millions of seeds are preserved for a future threatened by climate change, crop disease, war or environmental collapse.

But new research from Australia suggests that freezing seeds is not the same as protecting them forever.

Scientists studying thousands of seed samples have discovered that some tropical crops lose their ability to germinate much sooner than older estimates predicted. Mung beans emerged as one of the strongest performers, with at least 90 per cent of seeds in one 45-year-old batch still capable of germinating.


The result is encouraging, but it also exposes a serious weakness in the global seed-bank system. Many seed collections may need to be tested and replenished decades earlier than expected.

The study, published in Plant Genetic Resources, examined seed samples stored at the Australian Grains Genebank. Researchers assessed how well six tropical crops had survived under long-term storage conditions, offering a rare real-world picture of how seed longevity changes over time.

Seed banks are not permanent time capsules

Seed banks play a vital role in protecting agricultural biodiversity. They preserve crop varieties that may disappear from farms because of changing weather, commercial farming practices, pests or disease.

The seeds stored inside these facilities can later be used to restore lost varieties, develop stronger crops or support food production after a major disaster.

One of the best-known facilities is the Svalbard Global Seed Vault in Norway, often called the “Doomsday Vault”. However, it is only one part of a much larger international network. The Australian Grains Genebank is also home to a vast collection of crop seeds, including cereals, legumes and oilseeds.

At the Australian facility, seeds are sealed in packets under controlled conditions. They are stored at around -20°C, with low relative humidity, to slow down the natural ageing process.

Cold storage can greatly extend a seed’s lifespan, but it does not stop ageing completely. Over time, biological damage can build up inside the seed. Eventually, the embryo may lose the ability to begin growing, even if the seed still looks normal from the outside.

The major problem is that scientists do not yet have reliable longevity estimates for every crop. Predictions have traditionally been based on limited data, laboratory experiments or comparisons with related species.

That means some seed banks may be relying on storage schedules that are far too optimistic.

Thousands of samples reveal which crops survive longest

To understand how stored seeds were actually performing, researchers carried out germination tests on 3,861 seed batches held at the Australian Grains Genebank.

The samples represented six tropical crops:

• Sorghum
• Common bean
• Mung bean
• Soybean
• Pigeon pea
• Adzuki bean

Some of the seeds had been stored since the 1960s, giving scientists an opportunity to examine how different crops survived across several decades.

The results varied sharply between species.

Pigeon peas showed some of the weakest performance. After an average storage period of 36 years, only four batches recorded germination rates above 85 per cent. This suggests that many pigeon pea samples may need to be regenerated or replaced.

Adzuki beans also showed a relatively short average longevity estimate of approximately 17.4 years.

Mung beans, by contrast, performed particularly well. In one batch that had been frozen for 45 years, at least 90 per cent of the seeds were still able to germinate.

Common beans and soybeans also retained strong viability across long storage periods. Sorghum ranked behind mung beans among the longer-lasting crops examined in the study.

These findings do not mean that every mung bean seed will remain healthy for 45 years. Seed survival can vary depending on the original quality of the sample, moisture levels, storage conditions and genetic differences between varieties.

However, the results show that some crops can remain useful for decades, while others may deteriorate much faster than expected.

The biggest danger is outdated storage predictions

The most concerning part of the research is not that some seeds failed. It is that the failure happened much earlier than older models predicted.

Previous theoretical estimates suggested that frozen seeds from certain crops might remain viable for hundreds or even thousands of years.

For example, earlier predictions indicated that sorghum might only need to be checked once every 2,901 years. Mung beans were assigned a projected monitoring interval of around 2,075 years.

The new germination results challenge those assumptions.

Researchers found evidence of seed batches falling below 85 per cent viability after only 20 to 40 years, even under carefully controlled long-term storage conditions.

That creates a major practical concern. If seed banks follow outdated monitoring schedules, they could discover that a valuable crop collection has deteriorated only after much of its reproductive potential has already been lost.

The scientists argue that such long gaps between checks are risky. Germination testing is therefore not simply an administrative task. It is essential maintenance for the world’s agricultural safety net.

A seed bank may contain a rare crop variety, but that collection is useful only if enough seeds can still grow into healthy plants. Once viability falls too low, the seeds must be planted, multiplied and returned to storage.

This process is known as regeneration. It can be expensive and time-consuming, and it carries its own risks. Growing a seed collection outside storage can expose it to pests, disease, accidental mixing or unwanted cross-pollination.

That is why early testing is so important. It gives conservation teams time to regenerate a collection before the number of healthy seeds becomes dangerously small.

Why the mung bean result matters for future food security

Mung beans may not be the world’s most widely discussed crop, but they are important in many food systems. They are used in dishes such as soups, stews, sprouts and other protein-rich foods.

Their strong performance in long-term storage is therefore useful information for agricultural conservation. It could help seed banks refine their storage schedules and decide which collections require more frequent testing.

The research also carries a broader message: seed preservation cannot end when packets are placed inside a freezer.

Scientists must continue recording germination rates, comparing results across genebanks and updating predictions based on real evidence. Different facilities may also need to share information so that they can identify vulnerable crops before their collections become unusable.

There is another important limitation. Germination is only a measure of whether a seed begins to grow. It does not automatically prove that the resulting plant will be strong, fertile or capable of producing a healthy crop.

A seed may germinate but fail later in development. For that reason, germination tests should be treated as an important indicator of viability, not a complete guarantee of future agricultural success.

The researchers say that continued data collection will improve scientists’ understanding of seed longevity. Better information can help genebanks update their models and make more informed decisions about when to test or regenerate each crop.

The findings also offer a warning about how humanity prepares for future disasters. Preserving seeds is often presented as a one-time solution to a long-term problem. In reality, it is an ongoing responsibility.

The world may have stored millions of crop varieties for future generations, but those collections must be actively managed. Without regular testing and regeneration, some of the seeds intended to help rebuild agriculture after a crisis may no longer be capable of doing so.

The 45-year-old mung bean discovery is therefore both hopeful and cautionary. It shows that certain crops can remain viable for decades, but it also reveals that no seed bank can safely assume its contents will survive indefinitely.

The future of global food security may depend not only on what humanity stores today, but also on how carefully those seeds are checked tomorrow.

Frequently asked questions

1. What did scientists discover about 45-year-old mung beans?

Researchers found that at least 90 per cent of the seeds in one mung bean batch stored for 45 years could still germinate. This made mung beans one of the longest-lasting crops in the study.

2. Which crop performed worst in the seed-bank tests?

Pigeon peas showed some of the weakest results. After an average storage period of 36 years, only four batches recorded germination rates above 85 per cent.

3. Why do seed banks need to test frozen seeds?

Freezing slows seed ageing but does not stop it. Germination tests help scientists identify declining samples early so they can regenerate or replace them before too much viability is lost.

4. Does germination prove that a seed will produce a healthy plant?

No. Germination only shows that a seed has begun to grow. The plant must still develop successfully, reach maturity and produce a viable crop.