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Pollination: Beyond Bees and Flowers · Hydroponics Daily

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Hi, welcome back to Hydroponics Daily with me, Dr. Russell Sharp.
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Today is pollination. I'm probably going to do pollination over a few days,
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if not a whole week, because it's a massive subject area and I don't want to just gloss over it.
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And also, it's really interesting and it's a particular interest of me.
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I've studied pollination for a number of years on certain plants,
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some quirky plants, and I'll talk about that.
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And there are loads of really interesting stories about
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pollination relating to horticulture and then just wild plants
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in general so we're going to talk all about those and you'll
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definitely learn something new about plants in
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this podcast and the next few podcasts so
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pollination is simply the transfer of pollen the
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pollen grains those microscopic grains from the
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male parts of the flowers to the female parts it doesn't involve fertilization
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that's a separate process it's just the transfer so So fertilization is when
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the pollen tube generally germinates and grows into the ovules and fertilizes
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and transfers the genetic material.
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This pollination is just the
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transfer of the pollen. So it's equivalent to sex in humans and animals.
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It's called pollination. And as we say, the anthers, the male part,
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and then the surface of the female part is the stigma.
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And then the whole part of the the female part of the flower is called the pistol and.
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Malcolm McLaren the manager of the
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sex pistols he was in a biology lesson at school and he
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saw a diagram of a flower and it was labeled sex pistol and he thought that
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is a great name for a band and that's how the sex pistols got their name but
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that's a complete tangent let's get back to pollination and there are a number
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of different types of pollination and there are lots of horticultural and agricultural
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crops that require pollination.
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It's often said that 80% of all food crops require pollination by bees,
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and this is why bees are so important.
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If we didn't have bees, we would starve.
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And this is very much, in my opinion, an over-exaggeration. Bees are very important,
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but they're not that important.
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You've got to remember that all arable crops are wind
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pollinated and bees are not involved in that at all so and arable crops make
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up the vast majority of our calorific intake now we don't consume equal amounts
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of all foods so yes apples are require bees absolute requirement for bees for pollination,
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But it doesn't have to be honeybees. It could be a native bee.
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And flies and beetles are also involved in pollination.
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And the honeybee is a non-native species, unless you're, you know,
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I think mainland Mediterranean Europe, they're native, but in England, they're non-native.
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So there's a bit of an exaggeration there.
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And bees, so as I say, bees are not the only pollinators. birds
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can pollinate and important for certain crops hummingbirds
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especially and then there's wind pollination even
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water pollination water pollination is not that common even in aquatic plants
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most aquatic plants have flowers that come above the surface of the water and
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in our insect pollinated moths are a massive pollinator as well lots and lots
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of species of plants are pollinated by moths.
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But if we look at the earliest flowering plants, the magnolias and tulip trees,
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so these are plants that are evolved.
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Maybe during the dinosaurs or just after the dinosaurs i'm not sure timeline
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might be off on that but basically they're the earliest flowering plants and
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they don't even have separated petals and sepals they just have what's called
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teples and they don't have a distinct stigma at the center.
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And they're actually pollinated by beetles and the
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beetles would eat the flowers and the tissues and the teples
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as they're called and then transfer the pollen between
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plants and but beetles don't
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make great pollinators because they
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tend to eat the flowers and eat the the seeds
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and also if you've seen a beetle beetles are.
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Shiny and not much sticks to them and so
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that's where bees evolved so bees did not exist
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before flowering plants and bees evolved
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as pollinators that's that whole raison d'etre
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as the french would say so as our
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first look into pollination a really simple one to
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look at would be tomatoes and included
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that in that we would include everything in the tomato family
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so chilies eggplants what
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the crops have got in there potatoes in that family but we don't want
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pollination there the fruits are poisonous and carcinogenic
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so we can ignore that and tomatoes
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are self-compatible so they will
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self-pollinate so the pollen from
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the same flower can produce
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a seed if it if it gets to the
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stigma however in a in a very very in a
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greenhouse where there's no more air movement where it's stagnant then those
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flowers are not moving and you struggle to get fruit set so you can go in there
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and shake the flowers and you can and basically be a pretend bee and buzz the
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flowers. That's what my son loves to do in our greenhouse.
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But on a commercial scale, that's not possible. So they still bring in beehives
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into greenhouses in all around the world to pollinate tomato plants.
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And some people I know, certain commercial greenhouses, they wanted to save money on bees.
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And so they just got maggots from a local fishing shop and then they allowed
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the maggots to turn into flies and then the flies would pollinate the plants.
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Sounds disgusting, but flies are also really good pollinators.
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And so this worked for them and it was a cheap alternative.
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Companies like Biobest and Copper are going to hate me now because everyone's
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going to go out and buy maggots instead of their beehives.
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And as I say, not an absolute requirement for cross-pollination,
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but they do require pollination to form a good fruit. Same goes for strawberries.
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Strawberries require 25 visits, I'm told, by a bee to form a good fruit.
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If you don't get the pollen transferring to all of the stigmas,
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because there's more than one stigma on the flower, then the fruit will be deformed
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because the seeds aren't setting all around the fruit.
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And the seeds exude auxin i believe and
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that's what causes the strawberry to produce its flesh and so
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you you get really deformed fruit same
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with runner beans if you don't get really good pollination then
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you you won't get
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good bean set they are self-compatible
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most of the time and they have
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a probably an absolute requirement for bees because they've beans and
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anything the legume family has like a bee trigger type flower that
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sort of lupin type flower and other
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plants where you you are self-compatible that you
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would need really good pollination to get seed set even though
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they're self-compatible onions you might even have
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to resort to doing the pollination yourself if
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you wanted to get onion seeds so that you would like get
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a paintbrush or some something like that and and set it yourself all the crops
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require good pollination yeah raspberries raspberries gooseberries places like
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plants like these require really good pollination to get all around the fruit
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or on the flower so that you get really good formed and luscious fruit.
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Now, apples require really good pollination, but there's the added problem that
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apples are self-incompatible.
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And they're self-incompatible because they've evolved self-incompatibility mechanisms
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to prevent inbreeding depression.
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In humans, we know if you breed with closely related members of your family,
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you get a lot of inbreeding depression, you're not as fit, and you get diseases.
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Same in plants. And so they've evolved this mechanism, and this
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genetic mechanism to prevent them breeding
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with the same genetic or similar types and
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so a granny smith can't pollinate another granny smith because they've got
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this self incompatibility genes and so what
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you have to do as well as having to have two to three beehives in
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every orchard you also have to have a pollinizer and
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this pollinizer plant flowers at
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the same time as the variety you're growing that's crucial
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because apples and pears they can flower in
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distinct periods all through the spring so
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that's you have to flower at the same time and it also has
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to produce ample amounts of pollen it can
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produce the world's worst apples it can
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be a crab apple even but it just has produced
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loads because it's only its only job is to donate pollen
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into all those maybe there might be fuji apples
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or they might be all be not going to be red delicious anymore
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but maybe pink ladies they're a popular one now
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and so that's that that's its only job it's
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just a what would be like a sperm donor in humans that's what it is so golden
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hornet is a variety that's often used in apples and there are one or two self-compatible
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apple varieties however they're not grown commercially widely and even then
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they need good pollination.
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Self-pollination by a bee and to get good fruit sets just like the just like a tomato plant,
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and so you wouldn't want to grow them you can
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get apple trees they're called family trees where you
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graft four or five varieties onto one
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tree very popular if you want to if you've got a small garden and you really
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love apples and you want five different varieties of apples and there they normally
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match them up so they flower at the same time and so you you don't need to worry
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about pollination there they're
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probably going to get pollinated by just a few bees running around the.
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Plants in the daisy family and the poppy family are also very commonly self-incompatible,
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even though they have hermaphrodite flowers to prevent inbreeding depression.
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And so you'll need a pollinator there. Other things that apple growers do is
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they, or they've certainly looked at, researchers have looked at,
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is putting in chemicals that attract pollinators into the orchard.
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And eugenol, I think that's a terpene that's commonly found that attracts bees.
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And that can be this the people have
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experimented with including that into orchards and spreading that
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around orchards to bring in pollinators from outside you you
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might think that you would struggle to get enough pollinators
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if you were growing in a urban farm or an
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urban situation in say london but
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actually because beekeeping has become.
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Popular a lot of people have you know gotten the
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bandwagon of save the bees save the bees i love
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bees i'm going to keep bees there's so many beekeepers now
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that there's actually been reports of of honey
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levels declining amongst london beekeepers
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because so many people are keeping bees there's not enough flowers for
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them and so you this crazy situation
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where if you were growing apples in an urban you
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know in london you wouldn't struggle for pollinator because there's
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so many people keeping bees now that it's it's
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not an issue but now in the countryside it
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might be an issue especially in really windy exposed areas near
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the coast where the bees would struggle to fly or certainly
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where I live where it's so wet that you know it's always raining so
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there's no never going to be any bees flying around and in
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fact flowers sense this and many plant species don't open their flowers if it's
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not sunny and if it's raining and so you'll get lack of pollination there they
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simply don't open they don't produce nectar and pollen in those sorts of situations
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some plants you don't want pollination at all because it is a it's going to interfere with the.
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The harvested crop so not talking about things like lettuce where you
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just don't want flowering at all or cabbages you
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know you don't want the plants to bolt this is a case where you do want
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them to flower you do want them to fruit but you don't want pollination
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seed set and the first
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examples i'm going to talk about is cucumber cucumber is
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an interesting one because you don't want the seeds to set if you go in
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a greenhouse crop because it will produce bitter
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fruit that's why you go
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to commercial greenhouses often they have a tomato greenhouse
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and a cucumber greenhouse one they've got bit bumblebees in
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and one they haven't now if you're going cucumbers outdoors
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a lot of the varieties you do want pollination in because if you're growing
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in cooler environments and cooler conditions like in the uk this fruit will
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struggle to set and develop in cold conditions but if they're pollinated yes
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they'll have seeds in but they will develop in the colder conditions.
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And another example if we go to more extreme
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exact an environment hawaii hawaii
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is great for growing pineapples and lots of pineapple plantations and
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i think it's the dole company but it might be the del monte company they
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own vast areas of hawaii and
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they with the hawaiian government have prevented people
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from importing humming bees into hawaii it's against the law
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as i am understood to import hummingbirds into
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hawaii because they if they pollinate the pineapple
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plants which is what the pineapple has evolved it's a
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bromeliad and it's evolved in the jungles in the rainforests to
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be pollinated by hummingbirds but the pineapple fruit becomes.
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Bitter if it's pollinated and so they
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keep out hummingbirds and so if you
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grow pineapples in places with hummingbirds you get a more bitter
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fruit not a sweet so pineapples are
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an extreme example of where you want to keep out birds hummingbirds
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hummingbirds are have evolved a type of bird that's
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evolved as pollinators just like bees are
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a type of insect that evolved as purely as pollinators now
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there are other examples of plants like hops and
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hemp where you don't want
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to have pollination in certain situations but
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i'm going to cover them again tomorrow because that's moving
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into plant sexuality and we'll
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talk about dioecious plants and male and female plants
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and we'll talk about that tomorrow because that's another area and
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it's getting late now and i don't have the time to talk about that and
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i'll bore you richard if i just want to keep on mind about pollination and
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i'll also talk about my particular interest and
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my particular interest in pollination is about slug pollination
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and snail pollination and also a little bit about shrimp pollination which you'll
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almost certainly have never heard of but it's an interesting story okay thank
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you very much for today that's been hydroponics daily for today an introduction
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into pollination and its importance in various hydroponic crops.