Hydroponic Management - Hydroponics II

Course CodeBHT213
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment
Build on existing knowledge or experience in hydroponics.

 

This course is for someone interested in or already involved with commercial growing, who has prior knowledge or experience.

It has been designed by experts who have been advising commercial growers for years; with a view to solving the issues that are common problems for people who are already working in the hydroponic industry  (eg. on a farm, in a hydroponic shop or elsewhere).

 

Lesson Structure

There are 11 lessons in this course:

  1. How the Crop Plant Grows
    • Understanding how a plant grows in hydroponics
    • Plant growth factors
    • Roots, Stems. Leaves, Reproductive Parts
    • Manipulating and controlling growth
    • Light Levels, Air Temperature, Root Zone Temperature, Relative Humidity, Carbon Dioxide and Oxygen, etc
    • Heating and Ventilation Systems
    • Thermal Screens
    • Blackout, Shading and Lighting Equipment
    • Day Length Manipulation
    • Irrigation and Nutrition Control
    • Links to Weather Station
    • Controlling Plant Growth: Stopping, Spacing, Disbudding, Trimming, Training
    • Growth Control: Chemical and Cultural
    • Pest and Disease Disorder Control
    • Intercropping
    • Plant troubleshooting
    • Resources
    • Fruit set management
    • Pollination issues
    • Flower initiation
    • Flower and fruit development
  2. How to Run a Small Evaluation Trial
    • What is a Hydroponic Trial
    • Running a Crop trial
    • Setting up a Comparison Trial
    • Records and Recording
    • Evaluating the Trial
    • Research Methodology
    • Experimentation
    • Steps for Collecting Data
  3. Harvest and Post Harvest
    • Importance of Harvest and Post Harvest Management
    • Understanding Harvested Crop Physiology
    • Ripening of Fruit
    • Respiration
    • How and When to Harvest
    • Preparing Salad Mixes from Harvested Hydroponic Produce
    • Prevention of Bruising and Post Harvest Rots
    • Packaging
    • CA and MA Storage
    • Chilling Damage and Storage Te3mperatures
    • Harvesting and Grading Vegetables
    • Grading Standards
    • Fruit Grading Systems
    • Mechanised Grading
    • Grading Equipment
    • Harvesting Cut Flowers; stage, shelf life.
    • Post Harvest Treartments for Flowers
    • Grading Standards for Flowers
    • Conditioning and Packaging Flowers
    • Marketing: wholesale, supermarket, export, contract, local retailers, etc.
  4. Tomatoes
    • Growing Hydroponic Tomatoes
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
  5. Capsicum
    • Growing Capsicums; Bell Peppers in Hydroponics
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
  6. Lettuce, Salad Greens and Foliage Herb Crops
    • Lettuce
    • Celery
    • Chicory
    • Endive
    • Parsely
    • Spinich
    • Basil
    • Marjoram
    • Mint
    • Sage
    • Thyme
  7. Cucurbits (Cucumber and Melons)
    • Growing Hydroponic Cucumbers
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
    • Other Cucurbits in Hydroponics; Marrow, Zucchini, Melon, Watermelon, Pumpkin
  8. Strawberries
    • Growing Strawberries in Hydroponics
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
  9. Roses
    • Growing Roses in Hydroponics
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
  10. Carnations
    • Growing Carnations in Hydroponics
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
  11. Orchids
    • Growing Orchids in Hydroponics
    • Growing conditions
    • Nutrition
    • Suitable Systems
    • Culture
    • Problem Management
    • Harvest and Post Harvest for different Orchid Genera

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


Hydroponics offers more than anything else, possibilities for plant culture that did not exist before. In a hydroponic system, many of the manual tasks, and costs involved in soil culture can be eliminated, but there is a trade off. The set up costs are normally higher. Hydroponics can make better use of limited water resources, and can reduce or eliminate the need for chemical pest control in a commercial situation. Hydroponic produce can in fact be less tainted by chemical residues than produce from a traditional farm.
 
Hydroponics may offer the possibility of "perfect growing"; but in reality; things can still go wrong no matter what you do in horticulture. The fact always remains that you are dealing with living things and living things are never 100% predictable.
 
For Example:

What can Happen When the Nutrition Goes Wrong?
The nutrient solution in hydroponic systems provides an ideal environment for a number of other forms of life to grow and multiply. Plant life such as algae is common, and microbial populations exist in most healthy nutrient solutions unless some form of sterilisation is used. Nematodes, insects such as mosquito larvae and others, can proliferate in some nutrients and may cause plant growth problems. Nutrient solutions provide the ideal breeding ground for many plant pathogenic fungi and bacteria since they contain mineral elements, usually some organic matter, moisture and are often warmed to just the right temperature for optimum microbial growth. Bacteria, fungi and algae are also very commonly carried in water supplies, on media, seedlings and old root systems, on equipment, transported by humans, animals, wind and in dust, making complete avoidance difficult. Despite this, most well run hydroponic systems don’t often have problems with odour, bacterial growth or insects, but when they do establish, control needs to be swift as certain nutrient problems will rapidly cause root death and plant decline.

Algae

Most hydroponic growers come across algae sooner or later. It appears as a green, brown, reddish or black, slimy growth which clings to channels, gullies and pumps or spreads over the surface of damp media. Long strings of algae are common in nutrient tanks and return channels and the speed at which this form of plant life can grow and multiply is often impressive. Algae usually has an earthy or mouldy smell, and large volumes of decomposing algae in the nutrient can be responsible for unpleasant odours.

Algae is a nuisance to any grower as it not only looks unsightly, but has the ability to block drippers, emitter, pumps, return channels, filters and heavy growth can even seal off the surface of growing substrates, robbing the roots of oxygen.

The problem with algae, apart from the appearance and smell problems it can create, is not so much that it competes for nutrients with plant roots, but as it blooms, dies and decomposes, it sucks up dissolved oxygen from the system. This increases the biological oxygen demand (BOD) on the system and causes root suffocation from a lack of oxygen. Decomposing algae may also release toxins as it breaks down and provides a food source for plant pathogenic fungi which may then multiply to high levels in the system. Algae directly attached to plant root systems can suffocate the roots, making the plants prone to attack by opportunist pathogens such as Pythium.

Algae, is a form of plant life, and it is a natural consequence of exposing water with nutrients dissolved in it to a light source. Where there is no light, algae cannot grow, so the best solution to preventing algae growth is to stop light from reaching the nutrient solution where ever possible. Channels should have light-proof covers; return gullies also benefit from covers; large media beds can also be covered with either plastic film or a layer of substrate which is designed to act as a ‘dry mulch’ since algae can not grow on dry surfaces.

In aeroponic systems, the root chamber must be light proof and media pot or container systems can use plastic or rigid collars which cover the surface of the media. Plastic collars are available these days for rockwool propagation cubes – a surface which is usually green with algae by the time seedlings are ready for plant out. However, even in the best designed system, there is usually somewhere that light will fall on the nutrient – planting holes in NFT, return outlets in channels and tanks are common areas.

Control of algae, once established in a hydroponic system can be difficult – most growers tolerate small amounts of algae in the systems provided it does not become excessive. A regular scrub out between crops will often remove stubborn algae and is often the only control used by commercial growers.

Some growers do add algaecide products into the nutrient to kill off algae and there are a number of these products on the market. However, since any product which kills algae, a form of plant life, can also damage young or sensitive root systems, care must be taken with the dose and damage has been known to occur. Algae will also regrow very quickly after applications of most algaecide products, requiring regular applications to maintain good control.

Hydrogen peroxide can also be used added to the nutrient solution to kill of existing algae. However it has been found that dose levels of 50ppm of hydrogen peroxide (H2O2) is required to control algae, a rate which was phytotoxic for young plants, although older plants survived this dose rate. Therefore careful and selective use of H2O2 could be used on older, more resistant plants, but since H2O2 is a biocide rather than just an algaecide, there is always a risk of root damage.

Root Death
The major causes of root death in hydroponics are suffocation, starvation, pathogens, chemical damage, temperatures and EC/pH problems. In hydroponics, suffocation is probably the leading cause of root death and reduced growth rates. Often, any pathogens present won’t attack a healthy root system until it is damaged or weakened by adverse conditions – usually stagnation or suffocation in the root zone.

A lack of oxygen can be caused by flooding or ponding of the nutrient solution, decomposing organic matter in the solution, slow flow rates, and too many plants robbing oxygen from the root zone, which is accelerated as conditions become warmer. A lack of oxygen reduces the permeability of roots to water and toxins will accumulate as the root cells die. Some plants such as tomatoes, will attempt to adapt to the lack of oxygen by producing adventitious roots on the lower stem and swelling at the stem base.

 

WHO IS THIS COURSE FOR?

This course was developed to cover key issues which have been identified as recurrent problems for many experienced growers. It is suitable for anyone who has either completed hydroponics I, or alternatively, has significant prior experience.

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