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Manipulating Sex in Plants · Hydroponics Daily

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Hi, welcome back to Hydroponics Daily with me, Dr. Russell Sharp.
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If I'd been clever, I would have batch recorded all these podcasts,
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but I haven't been doing that.
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And it's getting really busy now because it's springtime and everyone wants
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spring fertilizer. So I've left it to the last minute. It's now half eight at night.
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I've cracked open a beer and realized I don't have the right lead.
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So I've whizzed around to my neighbor's Dan's house and on my scooter.
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So I sound out of breath, grabbed the lead and started recording this podcast.
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So yeah we've been really busy we've got
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loads of product out this week going off
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to all places all around the world on ships and
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so yeah it's been really exciting to get that out but thank god it's
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the weekend so now yeah we'll probably be working
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this weekend anyway so to carry on the
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podcast we were talking about plant sexuality yesterday and
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i said in this podcast we're talking about how you can manipulate that
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sometimes that's chemicals and sometimes that's environment
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and certainly when it comes to commonly cultivated
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plants in the curcubitaceae family
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or the pumpkin family cucumbers what
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else is in that squashes melons say cucumbers
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yeah they they are fairly easy to
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change the sex of the flowers i
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have to stop myself saying gender sex is the
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biology gender is you know anthropomorphic society
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you change the sex by basically well
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what you want to do when it comes to plants in the cucumbers and
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things like that you want to keep them cool and in short days because then they
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produce female flowers and they're monicious plants so they have male and female
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on the same plant and you want to promote females because that's where the fruits
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and the seeds will come from and in obviously melons you the fruit is still on the.
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Female plants you maybe want a seedless variety cucumbers again you might not
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want pollination but you want female flowers squash is the same giant pumpkins
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you really only need one female flower if you're growing a giant pumpkin.
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But you certainly don't want the case where your cucumbers are all male and that
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can happen if your greenhouse is too hot and if
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your plants are stressed so in in those
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plants you want to keep them cool and under preferably under
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short days that's why if you plant cucumbers and pumpkins
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a bit too late in the season they can all be male and you
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have really massive plants but no fruit on them and probably
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if you like is it melon fritters or you
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know pumpkin fritters where you use the male flowers then
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that would be a good thing but most people don't that's
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a secondary crop off the plant it's mainly
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the fruits you're going for this domination of male flowers in monoecious plants
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in warm conditions is actually a problem for some wild plants and the arctic
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willow for example it is dominated the more male flowers further south in the
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arctic and so with climate change and warmer summers,
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you're going to get more male and less seed production.
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And the same for the cloudberry, Rubus camiomorus, which grows in the Pennines
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in the UK, but it's on the southern end of its geographical distribution.
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And so the warmer the summers get in the UK.
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Then the less chance the cloudberry has surviving in its native environment,
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because soon the only cloudberries will be male
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cloudberries when it comes to hemp and
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cannabis i have read that sex is
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determined by x and y chromosomes just like it is
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in humans which is very much not
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the standard mechanism in plants however i'm not
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sure how true this is because you can
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use environment and chemicals to
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disrupt the sex of
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a cannabis and a hemp plant so you
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can't really do that in in humans
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and i don't see how you could do that if it was purely down
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to a chromosomal effect maybe the chromosomes only
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have a domineering effect but not
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an absolute effect when it comes to the hormonal
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control of flower production it is very much species
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specific so in some crops gibberellins
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promote femaleness in other crops ethylene promotes
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femaleness and if you
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look at things like bitter lemon sweet corn you can
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change the the the sex by adding different hormones courgettes are a good example
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of that where gibberellins and ethylene have been used to produce more female
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plants in certain crops and you'll have the opposite in other crops and in things
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like selenium, campion.
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Plant hormones have been found to have no effect on the sex of the flowers at all. So completely.
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It might be hormone-related, but the actual application of exogenous hormones,
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as we say, the application of synthetic hormones has no effect.
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There's a fabulous plant called the bloody arum, which is like a tropical vine,
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and there, sex is controlled by the age of the plant rather than the environment.
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So the floral spike is dominated by male flowers when it's young,
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and then as it increases it's as
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its age develops it turns more
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female with subsequent years so it's an
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age-related thing and then there's a
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good analogy to like um slugs slugs
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are slugs are born hermaphrodite but
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they don't have penises they have love
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darts and so they fire their love darts into
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another slug and then they become female for the
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rest of their life and then they're like eggs absolutely useless
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factor but interesting so you're going
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back to the bloody arum that becomes female as
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it it gets older you could imagine that a young plant can divert some of its
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resources to be to producing pollen and then when it needs to produce flowers
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and and sorry seeds and fruits which which is very energy intensive it's built up to a size where it can.
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Divert the resources to that when it's older.
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In certain maples, like the snake
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bark maple, drought stress induces the formation of more female flowers.
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And that's interesting because certain crops where you may want more females,
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that's an easy thing to change, isn't it?
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You can literally just dial back the irrigation a
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bit and then you could potentially create more
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female flowers perhaps the most interesting way of
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changing the plants sex is
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to is was found in bangladesh at
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the the university of chittagong in 1992
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where researchers decided they were
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going to electrocute a load of gourd plants and they
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found that this increased the proportion of
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female flowers on the gourd plants i would not
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advise do not try this at home do not start electrocuting your
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plants there is enough issues with electrocution and
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fires in indoor hydroponics especially with
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the introduction of under canopy lighting i
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think this is a recipe for disaster where you've got anywhere where you've
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got irrigation and electricity you've got
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to be really careful and electrocuting a plant
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is probably you know 80 90 water is also
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a recipe for disaster so there must be easier ways of
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producing female plants and electrocuting them so going
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back to hemp and legal cannabis it's ethylene seems to be the most important
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hormone when it comes to controlling the sex of the plant and it's not a it's
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not a black and white case so when you.
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When you treat the plants with ethylene-producing chemicals during its development,
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that actually prevents the formation of hermaphrodite plants.
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But if you want to make sure that the seeds of that plant are all female,
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then you actually spray it with ethylene inhibitors, normally silver thiosulfate
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or silver nitrate, something like that.
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And so you have to be careful what is a feminizing spray that is designed for
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the seeds that breeders would use, or is this something that you're trying to
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prevent hermaphrodites if you're producing a crop?
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So if you're trying to produce a crop, you would apply an ethylene stimulating
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chemical, and if you're trying to produce seeds that are all female,
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you would apply an ethylene inhibiting chemical.
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And both of those come with their issues. So silver compounds,
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although not extremely toxic can lead to a bizarre medical condition called argaria.
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I don't know how his other names, agariosis. And this is where your skin turns
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blue or blue-gray and your eyes go blue-gray.
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And I don't think it's a deadly disease, but you don't end up looking very good.
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I'm looking at the Wikipedia page here for it. And there's a
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man who looks very ill and
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doesn't look in the best of conditions and as
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i say a lot of the ethylene producing chemicals are not great
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for your health either so just be aware of that other interesting things when
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it comes to plant sexuality there's a the gunnerus like giant rhubarbs although
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they're not related to rhubarb from the south southern hemisphere there are
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lots of species in new zealand in the south pacific,
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and certain species only there's males on
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certain islands and females on other islands and so
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conservationists have done sort of like blind dates where they
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swap the males and the females around to help improve the
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populations there is a cycad
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from africa that has cycads are
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really interesting they've got rather than pollen they're another one with sperm
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and then they hold the record for the largest sperm in the biological world
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i think even bigger than any animal sperm blue whale sperm anything like that
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sperm whale sperm and talking a lot about sperm slap myself again Russell stop
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talking about sperm and apparently there's one species where there's only one.
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Only males survive, and they haven't got any females. I might be the other way around.
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And they're trying different ways to convert the plants that are there into
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the other sex so that they can produce seeds and hopefully mix the genes up
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and help with its conservation.
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Because at the moment, it's just clonal, and it's a risk because of that.
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That's it. I found it in my research here. it's
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the woods cycad encephalatos woody
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eye and hundreds of male
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species exist but there's no
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females the last specimen they're
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all generated from zulu land in 1895 and
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so i don't think they exist in nature anymore the woods
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cycad poor fella and scientists think
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that gene silencing and things like crisper could help
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with creating a female woods cycad
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so here's a challenge for you get yourself a wood cycad
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if you think you've got a good way of turning it into a
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female you could be a famous botanist for being the
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first person to generate a female woods
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cycad so i mentioned that i've studied pollination in
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the past and i just thought i'd talk about two examples where i've
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done research and about 2008 to
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2012 i was got really interested in
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a plant called wild ginger completely unrelated to ginger
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and i read in an obscure eastern
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european book from like the 1970s that people thought it was pollinated by slugs
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and snails and i looked at it and thought yeah that looks about right because
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the flowers were produced on the ground they were pointing down hitting the
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soil and so i went and they didn't they weren't like looked like they were attractive to.
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Flies or bees or anything or moths and i
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went and went to poland to look at the european
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species and found loads of eaten petals but no eaten seeds and no no leaves
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being eaten that was interesting and i went to china number of times and japan
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the study of serums and then i also try to find some asperdistra in the wild.
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Asperdistra is, well, it used to be a really common houseplant, not some more.
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And there was a study in the journal Nature, which is the most prestigious biological
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journal in the world, and in the 1980s, I believe,
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and that showed, the Japanese researchers showed that asperdistra were pollinated by a sort of.
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Freshwater shrimp that grew near these that
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lived in streams and so asperdistra is a
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wetland plant and it grows near rivers and
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it was thought that they they pollinate that so
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i would go off and find asperdistra plants as well and a
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serum and i'd go off into the the mountains
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of south east southwest china
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and i learned to write chinese i
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found i quickly found that if you try and speak chinese a lot
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of chinese people can't understand you no matter how hard you try so
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just learned to write it and i'd write i am looking for this plant and
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they go oh like i go to the local bar and then
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everyone gather around and say oh he's looking for this plant and they
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say please could you go and find this one oh he wants us
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to go find this one if you find this plant i will give you 10 pound or
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whatever 10 pounds is in renminbi and they
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would all go oh and they'd all rush off and try and find this plant
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they'd all bring back these plants and again no that's not
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the plant yeah that's the plant and we'd all go off and find this
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plant that was good fun probably a bit dangerous really
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looking back on it but i used to do that and then yeah good it was good fun
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studying bizarre plants got to see some strange parts of china i've never been
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to beijing only have i recently been to shanghai but i've been to some crazy
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places in guangxi in sichuan.
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Yunnan all up in the mountains searching for
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these plants around easter time so coming up to around now
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yeah so these all start to flower so if you're in poland go and
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have a look at a serum europium if you're in china or japan and
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then also go to california as well i used to go to california northern california
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and i used to just camp out and
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study the the serums there and
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look at the banana slugs that i was looking to see if
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they pollinated them there was loads of lovely species of wild gingers
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in northern california this is before i realized
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that northern california was a hotbed of you know drugs cultivation
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and it's before i watched the film zodiac and
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i was just camping by all these lakes having a
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great time and i came home watched zodiac on dvd
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i was like yeah that serial killer was killing all those people right where
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and he never got caught and and it was right where i was camping all the time
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i also learned that after about three weeks that it's illegal to just park your
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car at the side of the road in california and i must have done this about 400
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times looking for serums.
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Just stuck and pretty, again, pretty dangerous. Looking back on it,
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I just stagger across people's.
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Bunkers that they had in the middle of nowhere and they'd go what you're
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doing i'd tell them what i was up to and they'd help me find
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wild gingers so yeah if you're in northern california and
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you want to take a break from growing legal crops
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i'm going to go and find some of serum and see if
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they're pollinated by the the famous banana slugs which
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are probably the funniest looking slugs in the
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world then hit me up and i'll give you some advice thank you
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very much that's been hydroponics daily for today more about
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pollination there's probably loads more
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to do on pollination but i think three in a
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row is stretching the
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limits for everyone anyone listening so tomorrow i
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think i'm going to do a podcast about how
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and why i invented gold leaf the
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process of how i did it and where
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we've gone where we've come to since we did that
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so that should be an interesting one anyone who's
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used gold leaf or as it's called in the uk liquid gold it's also sold under
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a different brand in australia i think that'd be a really interesting one because
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it started off with very different aims as to how it is now where it's a premium
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fertilizer so it started off as a bit of a
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one for amateur growers who didn't know how to grow but it's very much not that
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now it's very much a product for people who want to grow the best crops so that's
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been hydroponics daily for today,
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changing plant sexuality. Thank you very much for listening.