Open Hydroponic Systems - an Overview

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Open Hydroponic Systems - an Overview

• Rian Briedenhann
• 27 82 565 5504

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Todays Situation

• Buzz words are quality hi-tech
• Plant manipulation
• More advanced fertigation irrigation
• No textbook response

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Scheduling

• Sunlight
• Biomass production
• Water
• Oxygen
• Nutrients

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Principles of Fertigation

• Concentration of individual inorganic ions in the
  plant depend on the
• Rate of uptake
• Concentration in nutrient solution
• Uptake of water
• Intensity of transpiration

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Principles of Fertigation

• Consumption rates of nutrients by the tree
• rootstock / clone combination
• plant population
• growth stage
• climatic conditions
• water supply
• plant size

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Open field hydroponics

• 3 Pillars of the system
• Maximum advantage of environmental factors
• Drip irrigation / Restricted rootzone
• Nutrient solution manipulation

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Environmental factors

• High noon - max sunlight and energy
• Will give us maximum
• Transpiration
• Stomatal conductivity
• CO2 assimilation
• Photosynthesis

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Physiological Aspects of Water Stress

• cell growth (-)
• wall synthesis (-)
• protein synthesis (-)
• nitrate reductase level (-)
• abscisic acid ()
• stomatal opening (-)
• CO2 assimilation (-)
• sugar accumulation ()
• proline accumulation ()

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Why use drippers ?
Dripper
Low O2 / High H2O
High O2 / Low H2O
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Photosynthesis
Non stressed
Rate
Stressed
12.00
6 pm
6 am
9 am
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Environmental factors

• Open field hydroponics

• Water requirement

• Area of water deficit

• Normal irri scheduling

• Growth period

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IRRIGATION SCHEDULING
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Pulsing
10
Pulsing
50 of PAW
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Soil moisture regimes
Rooting volume
115min
0.30.3
0.40.4
69min
0.50.5
415min
321min
0.60.6
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Factors affecting Fertigation efficacy

• Correct application techniques requires paying
  attention to the following
• Water quantity and quality
• Nutrients needs and demand cycle
• Fertilizers characteristics and compatibility
• Installations dissolution, storage, injection

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Environmental factors

• Management of environmental factors
• Orchard layout/design
• row direction
• ridges
• plant spacing
• trellis system
• cultivar / rootstock selection

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Open Hydroponic Production
Max. Adv. Of Environmental Factors


Drip irrigation
Nutrient Solution
Maximum Transpiration Stomatal conductivity CO2
assimilation Photosynthesis
Maximum yield and fruit Quality
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Complimentary Practices

• Tree Formation
• training method for light management
• Cultivar / Rootstock combination
• early production
• vigor control
• nutrient uptake
• fruit quality

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Complimentary Practices

• Spacing
• North / South orientation
• Pruning practices
• Hormone manipulation

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Complimentary Practices

• Stress management
• Growth regulation
• Girdling
• Fertigation
• 2 drippers per tree

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Complimentary Practices

• Stress Control
• Growth regulators
• Flower regulators
• Regulated Deficit Irrigation
• Pre bloom, Post bloom
• Pre harvest, Post harvest
• Girdling
• Fertigation
• Restricted root growth area - Drip pots

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Nutrient solution

• Soil contribution regarding nutrient supply??
• Fertilization program based on concentration and
  weight units per plant
• Composition of irrigation water considered when
  preparing nutrient solution
• Buffered at pH 5.8 - 6.2
• Adapted to the Phenology of plant (growth events)

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General formula for .

• More fruit and less wood production
• N (), P (), K (), Mg (--)
• More wood and less fruit production
• N (), P (-), K (--), Mg ()
• Good Fruit Grower Tree Fruit Nutrition, edit
  by A. Brooke Peterson and Robert G. Stevens

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TIME Growth Stage Development Phase
Mid-May to July Floral induction and initiation Transition of resting buds to floral buds
Aug. to mid-Sept. Pre-bloom Bud break and inflorescence development
Mid-Sept to Oct. Flowering Flowering and initial fruit set
Nov. to Dec. Stage I Fruit growth Fruit cell division and physiological fruit drop
Jan. to Apr. Stage II Fruit growth Fruit cell expansion
May onwards Maturation Fruit maturity and harvest
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Fruit World Fertigation systems(Very complex
system but shows need for automation)
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Mulching vs no-mulching OHS
With OHS, the objective is to form root balls as
close to the soil surface as possible to minimize
soil interaction with the nutrient solution.
Mulching speeds up the process of forming roots
near the surface.