Open Hydroponic Systems an Overview Rian Briedenhann +27 82 565 5504 Todays Situation Buzz words are quality & hi-tech
Plant manipulation More advanced fertigation & irrigation No textbook response Scheduling
Sunlight Biomass production Water Oxygen Nutrients 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 Principles of Fertigation Consumption rates of nutrients by the tree rootstock / clone combination plant population growth stage climatic conditions water supply
plant size Open field hydroponics 3 Pillars of the system Maximum advantage of environmental factors Drip irrigation / Restricted rootzone Nutrient solution manipulation Environmental factors High noon - max sunlight and energy
Will give us maximum Transpiration Stomatal conductivity CO2 assimilation Photosynthesis Physiological Aspects of Water Stress
cell growth (-) wall synthesis (-) protein synthesis (-) nitrate reductase level (-) abscisic acid (+) stomatal opening (-) CO2 assimilation (-)
sugar accumulation (+) proline accumulation (+) Why use drippers ? Dripper Low O2 / High H2O High O2 / Low H2O Photosynthesis
Non stressed Rat e Stressed 12.00 6 am 9 am
6 pm Environmental factors Open field hydroponics Water requirement Area of water deficit Normal irri scheduling
Growth period IRRIGATION SCHEDULING Pulsing 10 Pulsing 50% of PAW
mm Water Enviroscan Plot- T4, T5 120 110 100 90 80 70 60
50 40 30 Drip irrigation- 0.64 x class A pan 1/Week 3/Week Date
Soil moisture regimes Rooting volume 0.3*0.3 11*5min 0.4*0.4 6*9min
0.5*0.5 4*15min 0.6*0.6 3*21min 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 Environmental factors Management of environmental factors Orchard layout/design row direction
ridges plant spacing trellis system cultivar / rootstock selection Open Hydroponic Max. Adv. Of Production Environment al Factors + Drip irrigation +Nutrient Solution
Maximum Transpiration Stomatal conductivity CO2 assimilation Photosynthesis Maximum yield and fruit Quality Complimentary Practices Tree Formation
training method for light management Cultivar / Rootstock combination early production vigor control nutrient uptake fruit quality Complimentary Practices Spacing North / South orientation
Pruning practices Hormone manipulation Complimentary Practices Stress management Growth regulation Girdling Fertigation 2 drippers per tree 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 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) 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 TIME Mid-May to July Growth
Stage Floral induction and initiation Development Phase 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 Fruit World Fertigation systems (Very complex system but shows need for automation) 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.
