Beating the clock

This module should have convinced you how important it is to protect seeds while they are being processed between harvest and storage. Genebanks can control the temperature and humidity of the areas where seeds are processed: this does a lot to reduce aging reactions. But there are a lot of processes to get through, so perhaps the biggest challenge is controlling the amount of time it takes to process the seeds.

Watch this video, which shows the number of processes a genebank must carry out before seeds are ready for storage. Scientists at IRRI and IITA demonstrate these processes, while Fiona Hay and Olaniyi Oyatomi discuss some steps genebanks can take to ensure all processes are carried out efficiently. As you watch, think about how the scientists ensure the seeds’ passage through the genebank is as swift as it can be.

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Transcript: Video 3: beating the clock

Narration:

A new batch of freshly threshed rice. These seeds are as viable as they ever will be. Now they must be processed before they lose their ability to survive years in storage.

Fiona Hay:

When we harvest the seeds, we first take them off the plants, what we can say is that the, the clock is ticking. And if we keep the seeds too long in high humidity or high temperature, then that clock is going round faster and the seeds will be aging already.

Narration:

These maize seeds are starting their journey to be stored in the IITA genebank.

Olaniyi Oyotomi:

The life in the seeds are embryos, and then these embryos also are living things. So each time and all the time when seed are being processed for storage, the life of the embryo is the target to be protected.

Narration:

That protection starts in the drying room, so it’s important to get seeds in here as soon as possible. Inside the seeds, the biochemical reactions that promote ageing slow down, as moisture diffuses out into the cool, dry air. At IRRI, rice goes through two stages of drying. Three days at a higher temperature, then the process continuing in a cooler drying room.

Marionette Alana:

Every three days, we check again for its moisture. We want to if know once the seeds already reach less than 30% ERH, then that’s the time when we’re going to transfer the seeds in the net bags into paper bags.

Narration:

These drawers contain the original samples of every type of seed in the genebank’s collection. It’s important that new accessions match the old ones exactly.

Marionette Alana:

We need to authenticate first the harvest, because we have to know if the harvest they give us is the correct one. We compare it using our reference material, on what we call the seed file.

Narration:

These checks are essential for seed quality - whatever the crop.

Kofoworola Olatunbosun:

It is important to do the conformity check with a reference sample, to ensure we have seed purity in our genebank conservation, and to eliminate the debris, the broken seed and the off-type.

Narration:

Seeds that have come straight from the field may have been contaminated during planting, harvesting or threshing.

Kofoworola Olatunbosun:

you can see, the seed shape and the eye pattern are the same with this, while these are quite different, so that is why we do the conformity and the cleaning, to eliminate the bad seed from the good seed.

Narration:

Other seeds may be rejected because they are immature. Only the ripest and most well formed seeds will remain viable during storage. At IRRI, the unfilled seeds and chaff are literally blown away. This is cultivated rice. The genebank’s collections of wild rice require special treatment.

Arma Kristal Pabro:

Unlike the cultivated rice species, where we use the seed blower, for the wild rice species we use manual seed cleaning, where we take out the plant debris and unfilled grains in the harvest.

Narration:

Cleaning rice requires an eye for detail. For instance, the green colour of this seed tells the technician it is immature, and must be discarded. This makes manual cleaning a time-consuming process. But for some types of rice, technology can help. This is IRRI’s automatic seed-sorting device. First, the machine is trained on hand-selected rice of the ideal color, size and shape for the particular accession. Then, when a new seed lot is introduced, the machine will identify the very best seeds. This automated process reduces the time it takes to get through the sorting. But the seeds are still not ready for storage.

Marionette Alana:

After we have finished sorting the seeds we’re now going to give it to our quality personnel. She’s going to check again those selected materials and then prepare the seeds for viability testing and also the materials that will be sent to the seed health unit.

Narration:

At IITA, one of the seed health procedures is fumigation. It’s a chemical pest control treatment, to ensure the seeds are free of insects by the time they go into storage. If the seeds pass the phytosanitary checks, they’re ready to be counted.

Opeyemi Oyatomi:

What I am doing right now is to know the number of seeds. The first thing I do is to count one hundred seeds, to know the hundred seeds’ weight. Then I do the total weight of the seed. The system will do the calculation, and determine the number of seed we are having for conservation.

Narration:

At last, the seeds are ready for packing. They are placed in foil packets, and the air is removed to avoid oxidation. Cool dry and sealed, they’re now prepared for their long state of suspended animation. Throughout all these processes, the precious embryos have been kept alive.

Fiona Hay:

We always say that it's very important to get the seeds into a controlled environment as soon as possible. And of course, the best-controlled environment is the genebank storage rooms. The longer it takes before getting the seeds into genebank storage, the more the seeds will be aging and losing viability, and then their longevity will be compromised when they are actually in the genebank as well.

End transcript: Video 3: beating the clock

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Video 3: beating the clock