INDOOR CROPS Soilless
1 July, PGU.
Why is growing media important? • Growing medium - material where plants grow • Media – Provides nutrients by absorption through roots – Anchors – Anchors plants – Contains pore spaces which provide oxygen for roots – Provides favorable environment for microorganisms
Why is growing media important? • Growing medium - material where plants grow • Media – Provides nutrients by absorption through roots – Anchors – Anchors plants – Contains pore spaces which provide oxygen for roots – Provides favorable environment for microorganisms
What are the different types of growing media? • Soil – Thin layer of earth‟s curst that provides provides for growth of plants
• Soilless medium – Contains no topsoil
Components of Growing Media 1. Peat Moss- moisture and nutrients 2. Bark- substitution for peat moss 3. Sand- increases aeration and drainage 4. Perlite - increases aeration and drainage nutrients and moisture 5. Vermiculite- holds nutrients • Peat- lite mixes- common formulation of soilless media
• Bark-based mixes- commercially prepared bark based mixes that are substituted for sphagnum moss.
Perlite • Volcanic material • Provides drainage and aeration
Vermiculite • Heat treated mica • Holds moisture
• Sterilized organic compounds – Loosen the medium – Create larger air spaces between the particles – Include: - Peat Moss - Sphagnum Moss - Leaf Mold - Bark
Peat Moss
Sphagnum Moss
Leaf Mold
Bark
Soilless Structures
Environmental conditions • Lighting * In many climates it will be necessary to grow indoors under artificial lighting.
* This requires careful practice because it is difficult to replicate the performance of sunlight. * High Intensity Discharge (HID) lamps are a type of light that uses electric arc to produce light, (ex: Metal halide and high-pressure sodium lamps). Used in a combination these two types of lamps can be a substitute for natural sunlight.
• Ventilation
Is a key consideration especially when growing indoors under artificial lighting. The combination of lighting and plants generates excessive amounts of heat and humidity which will harm plants if not properly controlled.
• Irrigation systems and parameters pH and CF Conductivity (EC) for hydroponics • “Conductivity Meter” Device used to help monitor the concentration of nutrient solutions. (EC meter, CF meter or TDS meter ). • „Conductivity‟ represents the ease with which a solution conducts electricity. • Solid substances known as 'salts' (e.g. sodium chloride, potassium nitrate), yield 'ions' when dissolved in water. 'Ions' permit the flow of electricity through the solution.
• Increasing the concentration of ions improves the ease with which the solution carries an electric current and therefore causes a higher conductivity.
• Hence, an EC meter can be used to detect the presence of salts and their approximate concentration in water.
• Not all solutions or liquids conduct electricity Ex: petrol, alcohol and distilled water.
pH measurement and control • To ensure the long-term stability of nutrient solutions, it is important to maintain the pH between 5.0 and 6.5. This helps ensure all nutrients are available for root up-take. It also minimizes the risk of plumbing blockages.
Optimum pH of nutrient solutions
• The key reason for controlling the pH of nutrient solutions is to make sure that the individual elements in the nutrient remain soluble.
• If certain elements become insoluble, a white precipitate will form on the bottom of the reservoir.
Hydroponics The word hydroponics is comprised of two Greek words: „hydro‟ (water) and „pono‟ (labour)
Growing plants in a nutrient solution consisting of water and dissolved nutrient salts.
– Advantages • Complete control of nutrient solution • Greater yield per unit area through closer spacing of plants • Less spreading of roots • Reduced need for control of weeds, disease, and insects due to absence of soil
INDOOR CROPS HYDROPONICS • One of the most exciting challenges of indoor gardening is producing out of season fruits and vegetables.
• Change the way in which strawberries are grown in NZ. To obtain quality plant and fruit production, under protective cultivation.
Fruit, A frame hydroponics, showing root system of Camarosa strawberries, Dural NSW
•Hydroponic systems are classified according to: Substrate systems • Sand culture- plants grown in sterilized sand with individual drip irrigation • Gravel culture- involves irrigating plants grown in gravel for mechanical support.
• Bag culture- uses plastic bags that are filled with substrate, such as rockwool, peatlite, and sawdust. Drip irrigation used to supply nutrient solution.
rockwool
Cocotek mat
Bare root systems Aeroponic system • Involves plant roots suspended in air with a fine mist of oxygen-rich nutrient solution sprayed on them a regular intervals.
–Continuous flow system •Involves using shallow pools with panels containing plants floating on the surface
Flood & Drain (or Ebb & Flow) • In flood & drain systems, the nutrient is fed from beneath. This process floods the root zone to a pre-determined maximum level after which all the nutrient is allowed to drain back into the reservoir.
• This process is controlled by a pump, timer and a specialized „inlet‟ and „overflow‟ device: ‘Inlet’:
This also serves as the drain outlet. It is positioned as close as possible to the base of the flood & drain tray. Once pumping stops, the nutrient is able to fully drain into the reservoir via the inlet and pump. ‘Overflow’:
This is positioned at the maximum desired flood height. This means pumping can only flood to the height of the overflow. Suitable media for flood & drain include expanded clay, perlite or even none at all. The water holding capacity of the medium determines the feeding frequency.
Advantages to Flood & Drain systems • The flooding action helps prevent salt build-up in the root zone and achieves uniform root zone pH and conductivity . • Flooding purges stale (oxygen deficient) air from the root zone. Drainage draws fresh air back into the medium . • Flooding can enhance the penetration of disinfectants throughout the root zone.
Disadvantages to Flood & Drain systems • If no medium is used, pump failure can result in plant death within a few hours, especially in hot weather.
- Nutrient film technique (NFT) • NFT provides no medium support for roots. • Typically, roots sit in a long sloping irrigation channel. • Nutrient is introduced at the high end of the channel and allowed to flow over the roots after which it drains into a nutrient reservoir. It is then re-pumped back into the channel to repeat the watering process.
• This feed cycle can be intermittent or continuous.
Basic design requirements for NFT are: • Channels need suitable slope for drainage (i.e. gradient 1:40). • Channels must be wide and deep enough to comfortably accommodate the plant‟s mature root system.
• Undersized channel‟s can become choked with roots which can lead to damming, overflowing or create stagnant areas that fail to drain fully.
• The last plant should be positioned well upstream of the drain‟s outlet so that roots do not block the drain.
• Growth problems can occur as the channel length increases. Plants
at the head of these long channels often perform better than those at the „outlet‟ end.
• The threshold length will depend on factors such as the type of plant being grown and the nutrient strength.
Advantages to NFT • Lower water and nutrient consumption. • Avoids the supply, disposal and cost problems associated with media based systems.
• Relatively easy to disinfect roots and hardware compared to other system types.
• The absence of medium makes it easy to inspect roots for signs of disease, feed adequacy, etc.
• Regular feeding (and associated flushing) prevents localised salt build-up in the root zone and maintains uniform root zone pH and conductivity.
• Environmentally friendly, minimal potential for localised groundwater contamination.
Disadvantages to NFT • Pump failure can result in plant death within a few hours, especially in hot weather.
• Not suitable for plants with large tap-root systems (e.g. carrots). • Compared to run-to-waste systems, it is less suitable for saline (salty) waters because the salinity of the recirculating water gradually increases.
• Support beds structure
• Nutrition • The grower has the complete control over the implementation of various types of fertiliser including the type, concentration and the pH of the nutrient solution.
• The pH , temperature and EC/CF of the nutrient solution should be monitored, and the solution should be replaced to ensure successful hydroponic production.
Pests • It is commonly assumed that hydroponic agriculture systems are relatively free of insect pests and plant diseases because the technology is mostly enclosed. this is not true.
• Pest populations can increase with alarming speed in greenhouses because of the lack of natural environmental checks.
• Check foliage and roots regularly for signs of pests (and diseases). Problems can multiply rapidly if left unattended
• Whiteflies: There are about 1,200 different species of whiteflies. They are pests in many important agricultural and horticultural crops, both inside and outside the greenhouse environment.
• Spider mites (2 spotted mite): Tiny spiders appear on the plant as pinhead sized yellowish spots. They feed on sap and their presence is indicated by plants generally looking sick. They cause mottling of leaves that eventually turn brown and fall off. The formation of tiny webs indicates the problem is well advanced.
• Aphids: Pear shaped body typically ~2mm long; can be any colour. They suck sap from leaves causing leaves to curl.
• Thrips Appear 1-3mm long with hairy wings. They feed off plant sap causing damage to manifest as patches or streaks on the leaves.
• Scales Brown, oval and hard-bodied. They suck sap from leaves and stems.
Thank you!
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Glossary - CFL: Acronym for "compact fluorescent”. Chlorosis: The yellowing or whitening of normally green plant tissue because of a decreased amount of chlorophyll CO2: Chemical symbol for “carbon dioxide”. - Conductivity: EC. - Ground water: Under-ground water deposit e.g. artesian bore. - Hardness (or “hard”). - HID: Acronym for "high intensity discharge” lamp. - HPS: Acronym for "high pressure sodium" lamp. - Make-up water: Water used during the process of making a fresh batch of nutrient solution. - MH: Acronym for "metal halide" lamp. - Mottling: Spots or blotches of different shades or colours commonly found on leaves. - mS: Short-hand representation of "mS/cm". - Natural water: Water supply that is uncontaminated by pollution. - Necrosis: Death of plant cells resulting in dead/brown spots on foliage. - NFT: Acronym for "nutrient film technique". - Nutrient solution: The diluted nutrient that is fed to plants. It is usually comprised of a nutrient concentrate, water and nutrient additives. For the purpose of clarity, the nutrient solution is sometimes referred to as the "working nutrient solution".
