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For our farmers, harvest is the busiest, | 0:00:03 | 0:00:06 | |
most important time of the year. | 0:00:06 | 0:00:09 | |
It's the culmination of all their hard work. | 0:00:11 | 0:00:15 | |
I'm Stefan Gates, and I'm completely and utterly, | 0:00:22 | 0:00:25 | |
obsessively fascinated by food - | 0:00:25 | 0:00:27 | |
where it comes from, what it tastes like | 0:00:27 | 0:00:30 | |
and the extraordinary secrets lurking behind it. | 0:00:30 | 0:00:33 | |
But to grow good food, and to grow enough of it, farmers need to | 0:00:33 | 0:00:37 | |
intimately understand the science behind the harvest. | 0:00:37 | 0:00:41 | |
There are almost half a million different | 0:01:08 | 0:01:10 | |
species of plants on Earth. | 0:01:10 | 0:01:13 | |
We cultivate nearly 2,000 of them for food. | 0:01:13 | 0:01:17 | |
These edible plants provide us | 0:01:20 | 0:01:22 | |
with a dazzling variety of things to eat. | 0:01:22 | 0:01:25 | |
We harvest cereals and grains to make our bread. | 0:01:25 | 0:01:30 | |
And fruit and vegetables provide us | 0:01:32 | 0:01:34 | |
with essential vitamins and minerals. | 0:01:34 | 0:01:37 | |
Our ability to feed ourselves all depends on how well farmers | 0:01:39 | 0:01:43 | |
manage the needs of edible plants. | 0:01:43 | 0:01:46 | |
Take the potato - it feeds a vast proportion of the planet. | 0:01:46 | 0:01:49 | |
But it still shares the same basic characteristics | 0:01:49 | 0:01:52 | |
with the rest of the plant world. | 0:01:52 | 0:01:54 | |
Every plant needs its own particular balance of the same | 0:01:56 | 0:02:00 | |
key chemicals, so that it can grow. | 0:02:00 | 0:02:03 | |
And these are absorbed from the soil through the roots. | 0:02:04 | 0:02:08 | |
By adding fertilisers to the soil, farmers give their crops | 0:02:09 | 0:02:12 | |
a very specific cocktail of these chemicals, | 0:02:12 | 0:02:14 | |
and it makes sure they're as healthy as possible. | 0:02:14 | 0:02:17 | |
Yum-yum! | 0:02:17 | 0:02:19 | |
Phosphorous is essential for healthy roots and shoots. | 0:02:21 | 0:02:25 | |
Potassium strengthens stems, the plant's transport system. | 0:02:25 | 0:02:29 | |
Along with nitrogen, found in nitrates, these nutrients | 0:02:30 | 0:02:34 | |
help plants to create the energy they need to live and to grow. | 0:02:34 | 0:02:38 | |
Plants, unlike animals, are able to create their own food | 0:02:40 | 0:02:44 | |
through the process of photosynthesis. | 0:02:44 | 0:02:47 | |
This is why they're the first step in the food chain for us | 0:02:49 | 0:02:52 | |
and almost all other animals, and successful photosynthesis | 0:02:52 | 0:02:56 | |
is a fundamental part of growing crops for harvest. | 0:02:56 | 0:02:59 | |
But what does the process actually involve? | 0:02:59 | 0:03:03 | |
In order to grow, all plants have to pull off the same incredible trick. | 0:03:03 | 0:03:08 | |
They transform water and carbon dioxide gas into solid matter. | 0:03:08 | 0:03:15 | |
This amazing growth process is powered by the energy in sunlight. | 0:03:17 | 0:03:23 | |
Light enters the chlorophyll, | 0:03:23 | 0:03:25 | |
a green pigment contained within the chloroplasts in the plant's cells. | 0:03:25 | 0:03:29 | |
Here, it provides the energy that drives | 0:03:31 | 0:03:33 | |
the reaction between carbon dioxide and water, | 0:03:33 | 0:03:36 | |
to make glucose. | 0:03:36 | 0:03:38 | |
This provides the sugars that the plant needs to grow. | 0:03:40 | 0:03:43 | |
The by-product is oxygen - the oxygen we all rely on to breathe. | 0:03:43 | 0:03:49 | |
By measuring the speed of photosynthesis, | 0:03:49 | 0:03:52 | |
we can gauge how healthy a plant is. | 0:03:52 | 0:03:55 | |
The process is happening right here to this plant, | 0:03:55 | 0:03:58 | |
but normally it's invisible. | 0:03:58 | 0:04:00 | |
However, there is a way | 0:04:00 | 0:04:02 | |
in which we can see photosynthesis actually happening. | 0:04:02 | 0:04:05 | |
All it takes is a lamp and some aquatic plants. | 0:04:07 | 0:04:10 | |
If you look underwater, | 0:04:10 | 0:04:11 | |
photosynthesis is happening right now, and that oxygen | 0:04:11 | 0:04:14 | |
is being released as these tiny little bubbles. | 0:04:14 | 0:04:16 | |
The intensity of light affects the speed of photosynthesis. | 0:04:19 | 0:04:23 | |
Without enough light, the process will stop. | 0:04:24 | 0:04:27 | |
If I move the light further away... | 0:04:29 | 0:04:32 | |
..the bubbles slow down. | 0:04:34 | 0:04:36 | |
If I move the light closer... | 0:04:36 | 0:04:38 | |
..the bubbles speed up. | 0:04:40 | 0:04:41 | |
More light means more bubbles, | 0:04:41 | 0:04:43 | |
which means that photosynthesis is happening faster. | 0:04:43 | 0:04:47 | |
Faster photosynthesis means that plants can grow more quickly. | 0:04:49 | 0:04:54 | |
So farmers need plenty of sunshine for their crops to do well - | 0:04:54 | 0:04:57 | |
and that's why they say they're harvesting sunlight. | 0:04:57 | 0:05:01 | |
We expect fresh fruit and veg throughout the year. | 0:05:05 | 0:05:08 | |
So how do farmers grow their crops when there isn't much sunshine, | 0:05:10 | 0:05:14 | |
like in winter? | 0:05:14 | 0:05:15 | |
Greenhouses help farmers to grow their crops all year round, | 0:05:17 | 0:05:20 | |
which means that in the middle of winter, | 0:05:20 | 0:05:22 | |
and even in the middle of the night, they can grow tomatoes. | 0:05:22 | 0:05:25 | |
Not in this greenhouse, | 0:05:25 | 0:05:27 | |
but in a slightly bigger one that we found in Kent. | 0:05:27 | 0:05:29 | |
This greenhouse is gigantic - | 0:05:41 | 0:05:43 | |
about the size of ten football pitches. | 0:05:43 | 0:05:47 | |
It may be February, | 0:05:48 | 0:05:50 | |
but inside, it's possible to create the ideal conditions for growth. | 0:05:50 | 0:05:54 | |
The temperature, light and amount of carbon dioxide | 0:05:57 | 0:06:01 | |
can all be controlled to maximize photosynthesis. | 0:06:01 | 0:06:04 | |
Water and fertilisers provide all the minerals the plants need. | 0:06:10 | 0:06:14 | |
Growing crops like this costs money, | 0:06:21 | 0:06:23 | |
but with almost half a million plants in here, they can harvest | 0:06:23 | 0:06:27 | |
about 50,000kg of tomatoes every single week, even in winter. | 0:06:27 | 0:06:34 | |
And this way, they can meet our year-round demand. | 0:06:36 | 0:06:39 | |
Sometimes, with an understanding of exactly what a plant needs, | 0:06:42 | 0:06:45 | |
you can artificially create the ideal conditions for farming. | 0:06:45 | 0:06:49 | |
But farmers can't grow all of their crops inside. | 0:06:49 | 0:06:52 | |
So how does a plant cope | 0:06:52 | 0:06:53 | |
when photosynthesis simply isn't happening, like in winter? | 0:06:53 | 0:06:57 | |
Plants have their own strategies for surviving when it's freezing cold. | 0:07:02 | 0:07:06 | |
During the warmer months, | 0:07:10 | 0:07:12 | |
they save some of the glucose created through photosynthesis. | 0:07:12 | 0:07:16 | |
It's stockpiled in roots, stems and leaves | 0:07:19 | 0:07:23 | |
as a food store for the cold of winter. | 0:07:23 | 0:07:26 | |
We use these as food for ourselves, | 0:07:30 | 0:07:33 | |
and some of them are our most familiar vegetables. | 0:07:33 | 0:07:36 | |
Carrots are actually the plant's winter food supply, | 0:07:38 | 0:07:41 | |
stored in its roots. | 0:07:41 | 0:07:43 | |
Onions are basically energy stored up in swollen leaves. | 0:07:43 | 0:07:47 | |
And the potato is like a swollen, subterranean stem, | 0:07:47 | 0:07:51 | |
called a tuber. | 0:07:51 | 0:07:53 | |
For the plant, it's like an underground larder - | 0:07:53 | 0:07:55 | |
a stash of food to see it through the cold, dark winter. | 0:07:55 | 0:08:00 | |
Any extra sugars that the plant doesn't need to use immediately | 0:08:02 | 0:08:05 | |
are instead used as building blocks to make larger starch molecules. | 0:08:05 | 0:08:09 | |
Starch is insoluble, meaning it doesn't dissolve in water. | 0:08:10 | 0:08:15 | |
This makes starch much better than glucose for storing energy. | 0:08:15 | 0:08:19 | |
If potatoes weren't so starchy, they would draw in lots of water | 0:08:21 | 0:08:25 | |
from the soil, and all that precious food energy would be lost. | 0:08:25 | 0:08:29 | |
Every single potato is like a power cell for the plant, | 0:08:33 | 0:08:36 | |
packed to bursting with starch molecules. | 0:08:36 | 0:08:39 | |
And that means it's full of energy. | 0:08:39 | 0:08:42 | |
The potato uses its stored energy to grow a new plant in spring. | 0:08:44 | 0:08:49 | |
We use it for food. | 0:08:51 | 0:08:53 | |
I know when you taste a potato, you don't think of the energy, | 0:09:02 | 0:09:05 | |
but have a little look. | 0:09:05 | 0:09:07 | |
I'm going to put a couple of teaspoons of starch | 0:09:07 | 0:09:09 | |
into this bit of piping, and then blow it across a naked flame. | 0:09:09 | 0:09:13 | |
See what happens. | 0:09:13 | 0:09:15 | |
What you saw there was the energy being released | 0:09:22 | 0:09:25 | |
in just 30 or 40 kilocalories of starch. | 0:09:25 | 0:09:28 | |
The average potato contains around 150 kilocalories, | 0:09:33 | 0:09:38 | |
so about ten potatoes a day | 0:09:38 | 0:09:41 | |
would supply almost all the energy you need. | 0:09:41 | 0:09:44 | |
It's no surprise that lots of our most important foods | 0:09:45 | 0:09:48 | |
come from plants that are rich in starch. | 0:09:48 | 0:09:51 | |
As well as potatoes, these include grains like rice, barley and wheat. | 0:09:53 | 0:09:59 | |
Hidden in the ears of wheat | 0:10:01 | 0:10:03 | |
are the tiny grains that we use to make flour. | 0:10:03 | 0:10:06 | |
These are actually the plant's seeds. | 0:10:08 | 0:10:12 | |
They're packed full of starch and protein - | 0:10:13 | 0:10:16 | |
all created from the glucose the plant makes during photosynthesis. | 0:10:16 | 0:10:20 | |
So why do plants need to store energy inside their seeds? | 0:10:23 | 0:10:27 | |
Seeds are nature's way of ensuring that plants survive | 0:10:28 | 0:10:32 | |
into the next generation - but what exactly is a seed? | 0:10:32 | 0:10:36 | |
Seeds come in lots of different shapes and sizes, | 0:10:40 | 0:10:43 | |
but within every single one of them, new life has already been created. | 0:10:43 | 0:10:49 | |
This is a broad bean pod. | 0:10:49 | 0:10:51 | |
If I open it up, you find these. | 0:10:51 | 0:10:54 | |
These beans are all actually little seeds. | 0:10:54 | 0:10:58 | |
If I cut open the protective coating... | 0:10:58 | 0:11:01 | |
..and take a little look inside... | 0:11:03 | 0:11:05 | |
This little bit up here is the embryo - it contains all | 0:11:06 | 0:11:09 | |
the genetic information the seed needs to become an adult plant. | 0:11:09 | 0:11:14 | |
All the rest of the bean is the endosperm - | 0:11:14 | 0:11:17 | |
it's a package of energy | 0:11:17 | 0:11:18 | |
to support it on the first stage of its journey. | 0:11:18 | 0:11:21 | |
Given a very precise combination | 0:11:24 | 0:11:26 | |
of the right temperature and enough water, | 0:11:26 | 0:11:29 | |
the seed will germinate | 0:11:29 | 0:11:30 | |
and the plant starts to push up in search of sunlight. | 0:11:30 | 0:11:33 | |
Each bean contains about 1 kilocalorie - | 0:11:35 | 0:11:38 | |
the energy it requires to reach the surface. | 0:11:38 | 0:11:41 | |
Under optimum conditions, | 0:11:41 | 0:11:43 | |
it can grow at a speed of 3cm a day. | 0:11:43 | 0:11:47 | |
So, when farmers sow their crops at the start of the farming year, | 0:11:50 | 0:11:54 | |
each seed goes into the ground with its own store of energy. | 0:11:54 | 0:11:58 | |
But from day one, it's also crucial that farmers get things right. | 0:12:01 | 0:12:06 | |
If they plant their seeds when the ground is too cold | 0:12:09 | 0:12:13 | |
or too dry, they won't germinate. | 0:12:13 | 0:12:15 | |
From the minute they sow their seeds, | 0:12:23 | 0:12:25 | |
farmers must understand exactly what their crops need | 0:12:25 | 0:12:29 | |
to ensure a good harvest. | 0:12:29 | 0:12:31 | |
To produce seeds, plants need to reproduce. | 0:12:38 | 0:12:41 | |
And that's where pollen comes in. | 0:12:42 | 0:12:45 | |
Each microscopic grain carries the male reproductive cells of a plant. | 0:12:45 | 0:12:50 | |
For a plant to reproduce, | 0:12:50 | 0:12:52 | |
its pollen must reach the female parts of another plant. | 0:12:52 | 0:12:56 | |
The trouble is, plants can't really travel, | 0:12:56 | 0:12:58 | |
so finding a suitable mate can be pretty tricky. | 0:12:58 | 0:13:01 | |
And that's why lot of plants rely on animals to act as go-betweens. | 0:13:01 | 0:13:05 | |
To attract animal pollinators, plants entice them | 0:13:05 | 0:13:09 | |
with dazzling displays of flowers, rich with nectar and scent. | 0:13:09 | 0:13:13 | |
Birds, insects, and even mammals feed on the nectar, | 0:13:14 | 0:13:19 | |
and in return provide an invaluable service. | 0:13:19 | 0:13:23 | |
Flowers contain both male and female parts. | 0:13:25 | 0:13:28 | |
If you look at this beautiful lily, you'll see that up here, | 0:13:28 | 0:13:31 | |
these yellowy-brown things, these are called the anthers. | 0:13:31 | 0:13:34 | |
They're utterly drenched in pollen. | 0:13:34 | 0:13:36 | |
The anthers are the male part of the flower. | 0:13:38 | 0:13:41 | |
They stick out, so that any visiting creatures are sure to get | 0:13:44 | 0:13:48 | |
a thorough coating of pollen - | 0:13:48 | 0:13:50 | |
pollen they will then carry to the next plant. | 0:13:50 | 0:13:54 | |
Hopefully it will drop some of that pollen onto this part here - | 0:13:54 | 0:13:57 | |
the stigma, which is the female part. | 0:13:57 | 0:13:59 | |
And when the pollen drops there, | 0:13:59 | 0:14:01 | |
it travels all the way down to the bottom, to the ovaries. | 0:14:01 | 0:14:05 | |
Once it reaches an ovary, the pollen fertilizes an egg - | 0:14:07 | 0:14:11 | |
the flower can now develop seeds. | 0:14:11 | 0:14:14 | |
And with that, the plant has successfully reproduced. | 0:14:14 | 0:14:18 | |
After pollination, | 0:14:21 | 0:14:22 | |
in some plants, the flower will develop into a fruit. | 0:14:22 | 0:14:27 | |
The fruit will only start growing once the plant has reproduced. | 0:14:27 | 0:14:31 | |
So the huge variety of fruit that we eat wouldn't exist | 0:14:33 | 0:14:37 | |
without the help of animal pollinators. | 0:14:37 | 0:14:40 | |
On some large-scale fruit farms, | 0:14:49 | 0:14:51 | |
there are so many trees that an army of insects is needed to do the job. | 0:14:51 | 0:14:57 | |
There just aren't enough bees locally, so at this cherry farm | 0:15:01 | 0:15:04 | |
in Herefordshire, they import bumblebees by the box-load. | 0:15:04 | 0:15:08 | |
These bees are specially bred to do this. | 0:15:12 | 0:15:15 | |
We've relied on bees to pollinate our fruit trees for hundreds | 0:15:17 | 0:15:21 | |
of years, and they're every bit as important today. | 0:15:21 | 0:15:24 | |
Without insects like bees, there'd be no fruit. | 0:15:26 | 0:15:30 | |
And it's not just our fruit trees - | 0:15:31 | 0:15:33 | |
75% of all the crops we grow rely on animal pollinators. | 0:15:33 | 0:15:39 | |
Plants create fruits for one very simple reason - | 0:15:44 | 0:15:47 | |
to spread their seed as far and wide as possible. | 0:15:47 | 0:15:51 | |
The tasty fruit tempts animals to eat it. | 0:15:51 | 0:15:54 | |
Mmm. | 0:15:56 | 0:15:57 | |
The seeds inside the fruit pass through the animal's gut, | 0:16:00 | 0:16:03 | |
and are deposited far away from the parent plant. | 0:16:03 | 0:16:07 | |
But creating that fruit requires | 0:16:07 | 0:16:09 | |
a huge investment of energy for a plant. | 0:16:09 | 0:16:12 | |
That apple contained over a tablespoon of sugar, | 0:16:12 | 0:16:15 | |
which the plant had had to painstakingly create | 0:16:15 | 0:16:18 | |
using photosynthesis. | 0:16:18 | 0:16:20 | |
So plants won't give up their fruits | 0:16:20 | 0:16:22 | |
until the seeds inside them are ready. | 0:16:22 | 0:16:26 | |
And that's why unripe fruit is so unappealing. | 0:16:26 | 0:16:29 | |
These unripe apples are dry and sour. | 0:16:29 | 0:16:32 | |
They are packed with carbohydrates, | 0:16:32 | 0:16:34 | |
but they haven't been broken down into the sweet sugars we can taste. | 0:16:34 | 0:16:37 | |
Until they ripen, most fruits are green, | 0:16:39 | 0:16:42 | |
so that they're well-camouflaged within the plant. | 0:16:42 | 0:16:45 | |
But once they are mature, | 0:16:45 | 0:16:47 | |
the plant produces a syrupy-smelling gas called ethene. | 0:16:47 | 0:16:51 | |
This causes the fruit to become sweeter, darker | 0:16:51 | 0:16:54 | |
and much more appetising. | 0:16:54 | 0:16:57 | |
For the plant, this is the potential for a future generation. | 0:16:57 | 0:17:01 | |
But for us, it's a food | 0:17:01 | 0:17:03 | |
packed full of flavour and essential vitamins. | 0:17:03 | 0:17:07 | |
Once the fruit is ripe, | 0:17:11 | 0:17:13 | |
at harvest time, it's a real mission to get it picked before it goes off. | 0:17:13 | 0:17:17 | |
Cherries are a delicate fruit and need treating with care, | 0:17:19 | 0:17:23 | |
so it all has to be done by hand. | 0:17:23 | 0:17:25 | |
Fresh from the trees, they're brought here, to the pack house. | 0:17:29 | 0:17:32 | |
They're chilled, washed and sorted into different sizes | 0:17:35 | 0:17:39 | |
before being packed into punnets and shipped off to our supermarkets. | 0:17:39 | 0:17:43 | |
From tree to table is a very speedy process. | 0:17:46 | 0:17:50 | |
But strangely enough, the success of the cherry harvest starts | 0:17:52 | 0:17:56 | |
way back in the depths of winter. | 0:17:56 | 0:17:58 | |
Snow in January is great news for our fruit farmers. | 0:18:04 | 0:18:08 | |
It might not look like it, but inside the trees, | 0:18:13 | 0:18:16 | |
there's actually a lot going on. | 0:18:16 | 0:18:19 | |
The trees need the cold of winter | 0:18:22 | 0:18:25 | |
so that they can flower in spring, and then fruit in summer. | 0:18:25 | 0:18:29 | |
If they don't get enough chilling time, they might not fruit at all. | 0:18:32 | 0:18:36 | |
And it's not just about cherries. | 0:18:39 | 0:18:41 | |
All our fruit crops need to go through the cold of winter | 0:18:41 | 0:18:45 | |
if they're going to produce fruit. | 0:18:45 | 0:18:47 | |
So what's actually going on? | 0:18:48 | 0:18:50 | |
Well, it's all to do with the fact that plants really do feel the cold. | 0:18:52 | 0:18:57 | |
When the trees lose their leaves in winter, they become dormant. | 0:18:58 | 0:19:02 | |
That's because they are genetically pre-programmed to shut down. | 0:19:02 | 0:19:06 | |
But what is it that causes the tree to wake up again? | 0:19:08 | 0:19:12 | |
It's all down to a mysterious process called vernalization. | 0:19:12 | 0:19:16 | |
Take this apple tree. | 0:19:16 | 0:19:18 | |
It's only when the plant gets cold for a prolonged period of time | 0:19:18 | 0:19:22 | |
that another set of genes is activated - | 0:19:22 | 0:19:24 | |
and this begins the long process of preparing the plant for spring. | 0:19:24 | 0:19:29 | |
It's a bit like the plant's internal clock is being re-activated. | 0:19:29 | 0:19:35 | |
The long cold of winter triggers the release of hormones, | 0:19:38 | 0:19:43 | |
which kick-start the plant into flowering, and eventually to fruit. | 0:19:43 | 0:19:48 | |
To make an apple, the tree must endure around 700 hours | 0:19:50 | 0:19:55 | |
of temperatures colder than 7 degrees. | 0:19:55 | 0:19:58 | |
Without that, it simply won't flower as well when the weather warms up. | 0:19:58 | 0:20:03 | |
The success of the harvest will always be affected by the weather. | 0:20:08 | 0:20:12 | |
Urgh. | 0:20:12 | 0:20:14 | |
But farmers are constantly coming up with more and more clever | 0:20:14 | 0:20:17 | |
ways of controlling the environment to produce more, and better food. | 0:20:17 | 0:20:21 | |
Good job too. | 0:20:21 | 0:20:23 | |
As farming gets ever more high-tech, | 0:20:26 | 0:20:28 | |
some of our crops lead a really pampered lifestyle. | 0:20:28 | 0:20:32 | |
Polytunnels were first introduced to British farming 20 years ago. | 0:20:33 | 0:20:37 | |
They protect our crops from the worst of the weather. | 0:20:38 | 0:20:41 | |
Inside, it's possible to control the conditions. | 0:20:43 | 0:20:46 | |
These strawberries aren't grown in soil at all, | 0:20:50 | 0:20:53 | |
they're actually sitting in ground-up coconut shells. | 0:20:53 | 0:20:56 | |
They get all the water and food they need through a network of pipes | 0:20:58 | 0:21:02 | |
The amount of nitrogen, potassium, | 0:21:04 | 0:21:06 | |
and phosphorus is carefully measured to make the healthiest plants. | 0:21:06 | 0:21:10 | |
And to grow the very sweetest, plumpest fruit. | 0:21:14 | 0:21:17 | |
So by controlling the environment that they're grown in, | 0:21:17 | 0:21:21 | |
our farmers can increase the amount and the quality | 0:21:21 | 0:21:23 | |
of the fruit and veg that they grow. | 0:21:23 | 0:21:25 | |
Hmmmmm. That is fantastic. | 0:21:30 | 0:21:33 | |
But some farmers have taken it one step further, | 0:21:36 | 0:21:39 | |
and they're experimenting with even wackier techniques. | 0:21:39 | 0:21:43 | |
Miniature-sized versions of everyday veg are a real | 0:21:45 | 0:21:50 | |
favourite at fancy restaurants. | 0:21:50 | 0:21:52 | |
But how do you grow tiny vegetables? | 0:21:53 | 0:21:56 | |
Basically, it's all about density. | 0:21:57 | 0:22:00 | |
The plants are squashed together, with nearly 800 in a square metre. | 0:22:01 | 0:22:07 | |
Provided with the ideal conditions, they take just five weeks to grow. | 0:22:07 | 0:22:11 | |
And it's not just about the size. | 0:22:13 | 0:22:15 | |
Researchers have found that growing vegetables under red lights | 0:22:17 | 0:22:22 | |
speeds up photosynthesis, making them grow faster. | 0:22:22 | 0:22:25 | |
If red light is combined with blue light, | 0:22:29 | 0:22:32 | |
it also speeds up root growth. | 0:22:32 | 0:22:34 | |
And that can alter the taste, | 0:22:35 | 0:22:37 | |
and even make the vegetables better for you. | 0:22:37 | 0:22:40 | |
But in actual fact, our farmers have been experimenting | 0:22:42 | 0:22:45 | |
with how to make better food for thousands and thousands of years. | 0:22:45 | 0:22:48 | |
And to do that they have to understand | 0:22:48 | 0:22:50 | |
the process of natural selection, and then speed it up. | 0:22:50 | 0:22:53 | |
Natural variation in plants is down to chance. | 0:22:59 | 0:23:02 | |
Everything about them | 0:23:02 | 0:23:03 | |
is constantly being changed and refined by evolution. | 0:23:03 | 0:23:06 | |
Sometimes a mutation happens by chance that means a plant | 0:23:08 | 0:23:12 | |
is more likely to survive. | 0:23:12 | 0:23:14 | |
If you have a gene that makes you taller than your neighbours, | 0:23:14 | 0:23:17 | |
you'll get more sunlight, and so you're more likely to thrive. | 0:23:17 | 0:23:21 | |
Natural selection is a lengthy process. | 0:23:25 | 0:23:28 | |
But through artificial selection, farmers can speed things up | 0:23:28 | 0:23:32 | |
by selecting the characteristics we like best. | 0:23:32 | 0:23:35 | |
Mange tout peas are usually green. | 0:23:41 | 0:23:43 | |
The plant's genes act like an internal instruction manual, | 0:23:43 | 0:23:46 | |
telling it to produce a green pod. | 0:23:46 | 0:23:48 | |
But what if there's a chance mutant? | 0:23:50 | 0:23:52 | |
A random plant with purple pods, | 0:23:52 | 0:23:54 | |
and it's the purple colour that I want to keep? | 0:23:54 | 0:23:56 | |
By cross-pollinating the flowers of the purple pea plants with | 0:23:57 | 0:24:01 | |
those of other plants, it's possible to help it reproduce. | 0:24:01 | 0:24:06 | |
So we can artificially spread the genes of the purple pods around. | 0:24:06 | 0:24:10 | |
This increases the chances of purple offspring. | 0:24:11 | 0:24:14 | |
It's a painstakingly slow process | 0:24:16 | 0:24:18 | |
because you have to do this again and again over generations of peas. | 0:24:18 | 0:24:22 | |
But eventually most of my crop should be purple. | 0:24:22 | 0:24:25 | |
Farmers have been selecting plants with the characteristics | 0:24:31 | 0:24:34 | |
we want since farming began, | 0:24:34 | 0:24:37 | |
making them easier to grow as well as producing | 0:24:37 | 0:24:40 | |
a better end result. | 0:24:40 | 0:24:42 | |
Fruit that's sweeter. | 0:24:44 | 0:24:47 | |
Cereals that produce more grain, | 0:24:47 | 0:24:50 | |
or vegetables that are less vulnerable to pests and diseases. | 0:24:50 | 0:24:54 | |
Walk through a field of wheat today | 0:24:56 | 0:24:58 | |
and the crop stands less than a metre tall. | 0:24:58 | 0:25:01 | |
That's very different from the shoulder-high wheat that | 0:25:02 | 0:25:06 | |
farmers grew thousands of years ago. | 0:25:06 | 0:25:08 | |
And that's because farmers have artificially selected | 0:25:09 | 0:25:12 | |
for shorter wheat. | 0:25:12 | 0:25:13 | |
As well as being easier to harvest, it's less likely to be | 0:25:15 | 0:25:18 | |
damaged by bad weather, and creates less waste from the stalks. | 0:25:18 | 0:25:22 | |
So experimenting with new techniques to improve our food | 0:25:23 | 0:25:27 | |
is nothing new. | 0:25:27 | 0:25:29 | |
But there's one thing that really has changed the way | 0:25:29 | 0:25:32 | |
we grow our food in the last hundred years, | 0:25:32 | 0:25:34 | |
and that's the rise of the mega machines. | 0:25:34 | 0:25:37 | |
There's one machine in particular | 0:26:03 | 0:26:05 | |
that's completely changed the way we farm. | 0:26:05 | 0:26:08 | |
The combine harvester. | 0:26:09 | 0:26:11 | |
The first self-propelled | 0:26:16 | 0:26:17 | |
combine harvesters were only introduced to Europe in 1952. | 0:26:17 | 0:26:22 | |
Before that, wheat was harvested in pretty much the same way we'd | 0:26:24 | 0:26:28 | |
done it for thousands of years - by hand. | 0:26:28 | 0:26:30 | |
It took a lot of people power to bring in the harvest, | 0:26:32 | 0:26:35 | |
and the whole community had to pitch in. | 0:26:35 | 0:26:38 | |
But what once relied on an army can now be done with one machine. | 0:26:40 | 0:26:44 | |
This combine harvester has an eight-metre knife section | 0:26:45 | 0:26:49 | |
on the front, which makes around 1,300 cuts per minute. | 0:26:49 | 0:26:54 | |
It can harvest an area the size of a football pitch | 0:26:54 | 0:26:57 | |
in less than ten minutes. | 0:26:57 | 0:26:59 | |
But the real beauty of the combine is that it combines the job | 0:27:06 | 0:27:11 | |
of cutting and threshing the wheat, and that's how it got its name. | 0:27:11 | 0:27:15 | |
Inside the machine, | 0:27:18 | 0:27:19 | |
a set of centrifugal rotors | 0:27:19 | 0:27:22 | |
separate the grain from the rest of the plant. | 0:27:22 | 0:27:25 | |
The grain is collected behind the cab, | 0:27:25 | 0:27:27 | |
and the stems are spewed out the back. | 0:27:27 | 0:27:30 | |
Processed grain is ready | 0:27:33 | 0:27:36 | |
within seconds of the crop being cut. | 0:27:36 | 0:27:38 | |
Because they're so quick, and so efficient, machines like the | 0:27:40 | 0:27:43 | |
combine harvester make it possible to farm on a much bigger scale. | 0:27:43 | 0:27:47 | |
The innovation in the way that we farm never stops. | 0:27:52 | 0:27:56 | |
We'll keep on experimenting, | 0:27:56 | 0:27:58 | |
keep designing new and more efficient machines, | 0:27:58 | 0:28:03 | |
and who knows how we'll be growing our food in centuries to come? | 0:28:03 | 0:28:07 | |
What fascinates me about farming is this extraordinary | 0:28:08 | 0:28:11 | |
combination of technology, chemistry, | 0:28:11 | 0:28:14 | |
the magic of photosynthesis, | 0:28:14 | 0:28:16 | |
and the care and the love the farmer has to show to the crops. | 0:28:16 | 0:28:18 | |
And there lies the secret behind the food on our plates. | 0:28:18 | 0:28:22 | |
Subtitles by Red Bee Media Ltd | 0:28:45 | 0:28:47 |