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Inside the World of Pollen: A Deep Dive into Plant Reproduction and Hydroponics · Hydroponics Daily

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Hello and welcome back to Hydroponics Daily. This is your go-to podcast for
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everything soilless cultivation.
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I'm your host Dr Russell Sharp and today we're talking all about pollen and
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then I'm just going to give you an update on garden centre fertilisers which
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we talked about on yesterday's episode.
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So pollen, very interesting subject and something there's loads of really interesting
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facts about pollen that I'm going to go into towards the end of the subject
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but first I'm going to go into why pollen is important,
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what pollen is, and how to manipulate pollen in your hydroponic setup.
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So I think I've said on this podcast that pollen is like sperm for plants.
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That's an oversimplification because pollen is not sperm, although it does carry
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the male genetic material.
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So think of pollen as a delivery capsule.
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Each grain contains a vegetative cell that grows a pollen tube and a generative
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cell that divides into two sperm cells and those pollen,
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grains they can also be clumped together so in orchids you'll get a lot of pollen
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grains on like a pod so that each individual grain are released from the anthers
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the male parts of the flowers and they need to land on a compatible stigma so
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the way you remember that is stigma ma is.
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Mother in lots of languages including chinese and
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in english ma you say that where i'm
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from in the north of england ma for mother anther is
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male just think of android for that okay once
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on the stigma the pollen grain germinates and sends a
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tube down the style the style is
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the name for the little tube into the and delivers
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the sperm cell into the ovule so ovule is the same in
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human anatomy and that's when fertilization and
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seed development begins so that's very different to
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a sperm that swims okay so a pollen grain
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germinates produces a tube pollen comes
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in wildly different shapes and textures and a
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few different sizes and they are really
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interesting to look at under an electron or a fluorescent microscope
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some are sphere some are ovoid some
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are spiny and some are smooth small some are
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small like dust 10 microns 10 micrometers across
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these are mostly the wind pollinated from wind
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pollinated species because they don't want to float in the air and some can
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be massive 100 plus microns depending on the species as i said orchids produce
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a clump packs of pollen called pollinia whereas grasses make airborne wind dispersed
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pollen bees prefer a stickier textured pollen that clings to their hairs.
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Now bees didn't exist before flowering plants so they weren't around before
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flowers were around because bees need pollen and nectar to survive and that's why they're hairy.
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And before bees flowering plants had to rely on beetles which are shiny and don't.
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You don't hold on to pollen very good they're very poor pollinators
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so pollen size weight and texture is
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affected by the dispersal method the storage potential
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and contamination risk in controlled environments
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so storage potential is massive some species of pollen some plant species their
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pollen can only be stored for a number of days i think wheat is one of those
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so if you're thinking about breeding don't store it for ages or if it's one
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of these species check how long pollen can be stored for your species.
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There's been a lot of research on storing pollen for much longer now and that
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seems to be an area of active research amongst plant breeders.
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So pollinating crops indoors in hydroponics, especially in greenhouses and vertical
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farms, natural pollination often needs human help or technological help.
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Some common methods, hand pollination, best for tomatoes, peppers, cucumbers.
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You can use a brush, cotton buds or vibration tools.
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So that could be a modified toothbrush or
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you can use your imagination for what else it could be a modified form of and
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works well on a small scale but not good on a massive greenhouse
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you can buy in bumblebees commercial tomato greenhouses do this somewhere like
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copper sell them effective for buzz pollination species require a habitat box
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and consistent temperatures basically that's a cardboard box and they are regulated
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in some regions whereas in other regions you could just buy them in the post.
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Now if you're growing strawberries then you probably
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want to buy hoverflies and hoverflies are doubly good because not only are they
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going to pollinate their larvae will also eat and aphids and other pests so
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that's great less effective than bees but easy to manage in some systems and
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probably great for strawberries introduced regularly for best effect.
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Mechanical pollination you could have vibrating poles fans
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or air pulses good for automated systems when
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introducing insects and guests just having lots of air movement in
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your in your grow room will help with pollination cucumbers outdoors you probably
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want pollination or cold unheated greenhouses you want pollination because that
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will help with fruit sets whereas for heated greenhouses you don't want pollination
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and then things like legal cannabis and you don't want any pollination at all.
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So cucumbers, pineapples, you don't want any pollination, but they're pollinated by hummingbirds.
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So unless you've got hummingbirds in your grow room, you're going to be all right.
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So yeah, how can you prevent pollen from coming into your grow room in the air though?
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To say something like hemp, legal hemp or hops, they could come in through the air from a local plant.
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So you could use sealed grow chambers or air curtains, a HEPA filtration system.
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Obviously a carbon filter is going to be no good for this because it's not going
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to trap small particles, but they're only going to be limited in effectiveness.
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And most people don't have a HEPA filter on their inlet filter.
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So the best option there is not to go anywhere near people are breeding those
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plants and have male plants.
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Ozone could potentially destroy pollen as
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well as fungal pathogen spores a lot of people use ozone
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generators could degrade pollen viability but it's difficult in a growing environment
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and the ozone could damage the plant tissues and damage your lung tissues as
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well and your eyes so always use ozone very carefully in a tightly controlled
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environment there are now some growers using like peroxide generating.
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Misters but again that might help with pollen
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degrading pollen but again i won't want to be
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in an environment that's got peroxide in the
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air um so there's no foolproof method
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preventing pollen if you've got people with male plants in
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your area then you could get pollination if that's undesirable
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in your crop where is pollen also useful
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for it's not just a plant thing detectives police
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use pollen so forensic science pollen is
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species specific and incredibly durable so it
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might not survive but the actual pollen grain will stay intact for a long time
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so criminals have been placed at crime scenes via unique pollen signatures stuck
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to their clothing or cars especially if they've moved from somewhere with a
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rare plant type to somewhere where those plants don't grow near their house
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that's a great way of putting you at the scene of a crime,
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pollen traces can reveal origin of illicit goods or even drugs and fake documents.
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Safes and currency this is my favorite some high-end
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banknotes and vaults are coated with traceable pollen
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signatures to tag them the stolen
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items so when you drill into a safe you might think
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hooray i'm getting all these banknotes out but you're actually
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covering yourself in one specific pollen that
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could be used in court to put you at the scene of that
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bank heist so that's really interesting and pollen cores
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help scientists reconstruct ancient climates and plant
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life going back thousands of years so you can look at
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how so scientists do like ice cores to look at co2 levels
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they do dendrochronology where they look at tree
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rings to look at how the environment changed and they also look
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at pollen cores to see how plant species in that environment changed throughout
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the years so you suddenly had loads of cacti in a in a in a sediment then you
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know that it was pretty hot whereas if you had lots of arctic willow pollen
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then you knew it was going to be pretty cold at that time point when that sediment was laid down.
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And then also, I just want to talk about ginkgo and cycads.
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So ginkgo, the maidenhair tree, and cycads, a primitive plant that grows in Africa.
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Like other seed plants, male ginkgos and cycads produce cones,
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so a bit like a conifer, but they produce pollen
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grains which serve to carry the male sperm cells towards
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the female ovules but the difference here is that the sperm cells
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are flagellated and motile so they
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are like sperm and in fact cycads can
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be particularly large and i've been i've i've been
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to the tree in tokyo botanical gardens where it was discovered that ginkgos
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produce sperm so inside the pollen grains of ginkgos and cycads is a large coiled
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sperm cell with flagella basically tails and that swim to the egg once released
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so they're obviously going to need a wet surface to do that So unlike most seeds,
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like conifers and flowering plants where the sperm are delivered passively via
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a pollen tube, these ones, they swim.
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This makes them like a living link to earlier plant lineages where water was
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required for fertilization, like ferns and mosses.
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They're evolutionary oddballs in modern science and seed plants. So there we go.
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Know your crop. Take away messages. Know your crop. Is your pollination needed?
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Is pollination not wanted?
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Choose the right pollination strategy. Can you do it by hand?
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Do you need to get insects in?
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As I say, you can buy in bumblebees. Another option is just to get
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down to the fishing shop and buy some maggots bumblebee and
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they'll create blue bottles or green bottles depending on the species of maggots
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you get not the best pollinators in the world but a hell of a sight a lot cheaper
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than bumblebees and a lot easier to get hold of if you're a small grower you
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just have to deal with the blue bottles in your grow room after you've you know
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grown your strawberries or whatever it is you want looking to get pollinated
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tomatoes if you're growing
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dioecious plants make sure you you have some sort of filter on your inlet filter
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if you've got male plants nearby especially if you're breeding yourself you
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know that's a recipe for disaster.
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Pollen is sticky sneaky and stubborn and can
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spread and some can survive a long time so it could survive to
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surfaces and then i was just going to
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that's pollen for today so it's been hydropower study for today i was going
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to give you an update on garden center fertilizers got some data for you i had
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a look at the best selling garden center fertilizers in the uk which are also
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some of the best selling in the us and other countries and had a look at their
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safety data sheets to see what they contained.
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I knew some of this, but I just wanted to confirm it.
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Fostrogen, that's a very old school, popular one, that contains over 35% chloride salts.
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We said that chloride salts were the cheapest and most inferior form of fertilizer.
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And so they contain mostly, most of their fertilizer ingredients is this inferior
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form for fostrogen, which some growers think of as being like,
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you know, top end fertilizer.
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Tomorite, you know, the names and the bottle and
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the name suggests this is for tomatoes zero calcium despite
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blossom end rot being the number one problem for tomatoes tomorite contains
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zero calcium miracle grow pour and
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feed this is the trade name for that ready to
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use products that i talked about over 99 water
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and then maxi crop that's the best selling seaweed and
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then inverted commas fertilizer seaweeds are
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not fertilizers they're biostimulants and so no surprise that.
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Maxi crop all the nutrients come from fertilizer salts
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added to the formulation not from the seaweed itself
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and then there's those ones that say you
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know focused on cacti focused on african violets
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and things like this and they were down at ph2 so
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and obviously not great for plant growth their ph2 will strip
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calcium particularly out your plants so you
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get very weak plants if you use those so they
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are by far the most popular five different types
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of fertilizers definitely here in the uk they've all
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got massive problems with them so garden center fertilizers as
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i said yesterday they suck big time and so
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that's why we don't sell at any products
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at utreema gold leaf liquid gold any of our products
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in garden centers because we're not here
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to satisfy the demands of the
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finance directors of garden center chains we're here
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to satisfy the demands of plants and their
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productivity and health so yeah garden center fertilizers not great so if you'd
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like any more information on pollen you think i've missed something crucial
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then give me a bell and if you found this useful please do share it on social
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media and tag us so that i know you've shared it that would be fantastic thank
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you very much for listening and until tomorrow goodbye.