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Regulated Deficit Irrigation - Hack your crop quality · Hydroponics Daily

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  Hi, welcome back to Hydroponics Daily. Today's topic is regulated deficit irrigation.
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  This is an alternative to the use of growth regulators in hydroponics.
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  So really important for optimising the ultimate yield of your crop,
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  avoiding those nasty chemicals that are hazardous to your health and also limit crop quality and yield.
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  This method actually increases quality, so it's a great method.
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  There's two methods we're going to talk about today and tomorrow this one is
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  regulated deficit irrigation and the other one is partial root zone drying so
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  regulated deficit irrigation or rdi.
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  Is where you take a well-watered plant
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  as a reference in your grow room and you
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  work out how much it weighs when it's
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  well watered and how much and then you
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  you calculate how much water it's lost in a
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  24-hour period and that water has been
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  lost from evaporation from the soil surface and from
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  transpiration the loss of water through the stomatal pores in the leaf that
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  is a hundred percent potential evapotranspiration okay so you can just use a
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  weighing scales a balance to work out what how much that water is in your reference
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  plant you might have one or two
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  reference plants they should be representative of all the plants in your.
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  Room and then to impose a
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  regulated deficit irrigation you only apply
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  75 percent of the water that reference
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  plant lost to all your crop so each plant
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  only receives 75 percent every day and then
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  the well water plant obviously receives it all back because then
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  you calculate it every day or every other day how much
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  the reference plant has lost because this will vary according
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  to the temperature according to the humidity and so
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  to keep a stable deficit you want
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  75% going back in so if it's 100 grams of water
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  has been lost you add 75 grams and ratio
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  it that way now this will impose over time a
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  very mild water deficit on your
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  plants they'll lose water slowly they won't dry
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  out they won't die because they're always getting some of the
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  water they require now why does this improve crop
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  yield and crop quality it's because a plant that receives all the water that
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  it needs doesn't actually grow in the optimum way it wastes a lot of growth
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  it produces a leggy growth and so actually mildly stressing it produces hormones
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  like aba abscisic acid and jasmonic acid and salicylic acid that.
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  Reduce growth slightly and also make the plant hardier to pest and disease.
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  And produce more flowers to leaf ratio and produce a better crop with higher
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  concentrations of bioactives, tastes and chemicals.
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  It's been found in numerous studies that an RDI regime produces a better quality
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  crop and doesn't actually significantly impact yield.
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  And if it does impact yield, you're more than happy with the trade-off that
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  it's giving you for, excuse me, for increasing crop quality.
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  And a lot of hydroponic growers are going after quality, not quantity when it comes to yield.
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  If you did a 50% RDI, you'd get a severe stress. You can play around with the exact figure you want.
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  I've imposed both 50% and 75% and seen really good effects on flowering amounts.
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  You can find those studies that I published on flowering in rhododendron,
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  a perennial crop that flowering is very important for and
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  and using that as an alternative to growth regulators so that's
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  regulated deficit irrigation if obviously as
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  the control plant grows it's going to get add weight
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  so you need to factor in that that's another complication so you
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  you might want to increase your what is your reference weight for well
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  watered over time but it's a very good method it's
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  better than just removing watering altogether or you know it's more precise
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  it's a gentle form that doesn't stress the plant extremely It just gives a nice
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  dose of those hormones like ABA that just keep growth in check and keep quality high.
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  We'll do partial root zone drying tomorrow. I definitely recommend this one.
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  This one is the easiest, easier of the two methods to look at.
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  If you've tried RDI and you've seen positive or negative effects, drop a comment below.
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  And really interesting to see this on hydroponics, if anyone can impose this
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  on a hydroponic crop. Thank you very much.