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Flower Colour Manipulation · Hydroponics Daily

• 0:00
  Hello and welcome back to Hydroponics Daily. I'm your host Dr.
• 0:04
  Russell Sharp and this is your podcast for everything soilless cultivation.
• 0:08
  Today I was going to do a podcast episode all about cut flower production in
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  hydroponics and how you grow cut flowers,
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  however that turned into a behemoth of an episode and so I'm going to cut it
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  down into a few different episodes and today I'm going to talk about how you
• 0:26
  can manipulate flower colour and even shape. So manipulating flowers.
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  Normally this can't be done. So when you grow a plant,
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  whether you change the, when you change the fertiliser, the environmental conditions,
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  things like this, you can massively change the way a plant looks from its leaves
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  and its roots and its stems and its fruit, but you can't really manipulate flowers.
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  But scientists have done a lot of studies on plants over the years and there
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  are some exceptions and some really interesting exceptions so we'll look at
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  that in this episode today.
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  So the first thing is that many cut flowers species show reduced petal colour
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  intensity when grown above optimal.
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  Temperatures so when they're grown in really high temperatures their flower
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  color can fade that's interesting and that's why you should avoid really high
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  temperatures now that doesn't mean light levels that just means temperatures
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  so you'll find that a lot of cut flowers are grown in high altitude areas where
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  the air temperature is low but the high level the light levels are,
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  the light levels are high and the air temperature is low for that reason to
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  make sure you get the most intense colours.
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  High heat temperatures suppresses anthocyanin biosynthesis.
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  So there's a plant called lisianthus, or eustoma is its scientific name,
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  and that's one way you'll find the most effect.
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  And lisianthus, or eustoma as they're called, they are very,
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  very pro, they're the one flowers you can manipulate the most.
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  So conversely, cool night temperatures late
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  in flowering can boost color in anthocyanin-rich
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  flowers and that includes legal cannabis
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  that of the purple varieties so cool night temperatures and it's even this is
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  technique is used by some growers who can't cool their air temperature they
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  actually put iced water onto the onto the root system into the grow media and
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  that's how they can boost the purple color.
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  Now we've got led lights we can produce tune tunable
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  led lights in the past we just had
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  sodium lights or sunlights and a few
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  filters that we could put on to manipulate the spectrum now we
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  can do massive things so red and blue leds increase anthocyanin production in
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  lettuce red and blue leds double anthocyanin levels in the leaves obviously
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  not in the flowers because they have white flowers and nobody cares about lettuce
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  flowers but that just shows you that anthocyanin levels can really increase
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  when you use an LED, red-blue LED.
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  In lisianthus, as we said, high temperature almost bleaches the petals,
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  but increasing the light levels, especially in the leaves, boosts the colour
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  intensity in the flowers.
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  More photosynthesis equals more sugars, more pigments, so just think of it like that.
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  And sunflowers like osteospermum hybrids only open during bright sunshine,
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  meaning the colours are show only in ideal light conditions that's something
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  that's to consider now let's look at the effect of biochemistry and ph influence
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  anthocyanins shift between red purple and blue depending on the ph and the copigments in the tissues,
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  You can think of cabbage. When you put cabbage in vinegar, it goes bright purple.
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  If you were to put it in something like bicarbonate of soda,
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  it would go pink or creamy colored.
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  So they almost act as like an indicator dye.
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  But the most common one that we talk about when it comes to pH is hydrangeas,
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  and hydrangeas are a cut flower.
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  They're very expensive cut flower as well so hydrangea macrophylla
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  and hydrangea serrata they're the
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  two species that show dramatic color change with soil ph it's
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  only those two species i think other species well you
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  won't you won't see this especially because they're white flowers as
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  well a lot of them so in acidic soils with a
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  ph of 5.5 or below aluminium binds
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  to the pigment in the petals and that gives you a blue flower aluminium is soluble
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  in low ph soils it's toxic to most plants but hydrangeas are what we term ericaceous
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  or calcifuges and they can tolerate the aluminium and they can use it to bind to their pigments.
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  If you've got neutral or alkaline soils there's no aluminium there to take up
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  and so you get pink or red to cream flowers mainly like a light pink.
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  I prefer the light pink but many people prefer the blue and you can buy aluminium
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  in an acidic form to spray on hydrangeas at most uk garden centers only certain
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  varieties of anthocyanins respond so white flower cultivars remain unchanged
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  because they haven't got any pigment.
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  What else can we say about that there are some other
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  chemicals there are some products
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  on the market that are designed to increase or change flower
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  color especially in the legal cannabis sector purple producing
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  products and at eutrema we have tried
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  to make compounds for increasing anthocyanin
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  levels in flowers we've tried a number of different active ingredients
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  we've tried our salicylic acid product we've tried what
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  else have we tried abscisic acid we've tried
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  all sorts of things really and none
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  of them have worked so we've not released a product to change flower color
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  so you know even the greatest
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  minds can fail at this and some mediocre ones like mine
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  but if you've got an idea for a product that can change flower
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  color then let me know we can collaborate in the
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  late 1990s french researchers found significant color
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  variation in a single tulip variety depending on
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  the growing regions that where the tulip was grown in spite
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  explaining why the packet art you get with you when
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  you buy a flower or a bulb doesn't always match what
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  you get when you grow your plants in your soil and then interestingly forget-me-nots
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  which grow as a wildflower here in the UK or as a flower that you can grow in
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  an English country garden they shift from pale pastels to vivid blue as they
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  mature and I think they also change colour once they've been pollinated.
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  I'm pretty certain on that so practical techniques
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  for growers keep your daytime temperatures optimal use cooler
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  nights to boost pigments late in flowering avoid high
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  temperature stress during flowering to prevent washed out colors
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  use an led light that's got
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  it's tunable and you can increase the red and blue to
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  enhance flower production ensure high
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  light levels on foliage not just the flowers the
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  plant needs energy it needs sugars to make them you could
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  even look at feeding your plants high
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  sugar concentrations we think about these as sugar
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  or carbohydrate based products it's like resonator type
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  products you might see them in hydroponics we think of them as for
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  like resin production but they can also be good for improving pestle color
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  if you're going something like lisianthus and then if you're trying to shift
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  the actual color you can mess around with ph lowering the ph adding aluminium
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  sulfate to produce more blues if it's hydrangeas or raising the pH and adding
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  lime if you want pink or red hydrangeas.
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  Have a go at changing the pH and adding aluminium, sulphate or lime if you want
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  to mess around with how that affects pigment production in your plant.
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  You've got a few plants to spare, that'd be a good interesting study if you're
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  prepared to mess around with them that close to flowering and harvest.
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  As I said, not all species respond to these interventions, only anthocyanin-rich varieties.
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  Most plants, no matter how you grow them, the pigment won't change,
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  especially those based on carotenoids, betalanes.
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  So that's a really difficult one for me to say. They're the pigments found in
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  sugar beets and other types of beets.
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  They will affect change according to pH, but not so much light.
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  So that's something to consider.
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  So know your pigments, control your temperatures, use LED lights.
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  Mess around with pH and lime and aluminium sulfate if you want to mess around
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  that and mess around with adding sugars as well,
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  so you can in some certain circumstances change
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  it it isn't just about genetics obviously you can breed different
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  colors you can cross one a green variety with
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  a purple or a black or you know and produce different color
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  flowers but environment can have a small effect
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  as well in certain species i'm dr
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  russell sharp thank you for joining me for hydroponics daily i will
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  do another episode at least possibly two or three on cut flowers we'll talk
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  about day length and cut flowers we'll talk about where cut flowers are grown
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  and certain techniques for propagation and why hydroponics might be used instead
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  of soil cultivation so thank you very much for listening and until time until
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  next time that's been hydroponics daily.