Aeroponics - Fukta rötterna

I ett Aeroponic system, används en pump för att spruta en vattendimma över rötterna i vattenbehållaren vilket ger hög grobarhet, högre växter och starka rötter. Så länge som vattentemperaturen är mellan 17C - 22C. Några system har automatisk temperaturreglering där temperaturen i ”rotkammaren” ständigt regleras och vattendimman används för att kyla rotkammaren.

Vattendimma
En metod är att i intervaller ha vattendimma i 3 minuter var 5 minut. Denna intervall kan användas under hela tillväxttiden. Intervallen ser till att rötterna aldrig torkar och de får rätt tempererad näring kontinuerligt och mycket syre.

Kontinuerlig dimmning
Med en korrekt temperatur av 17C - 22C, och syre kommer roten att hålla sig frisk och producera en extremt stark planta.

Dimm intervall
Med intervall ökar också syret till rötterna. Börja med att sätta timern till 1 minut till och 1 minut från. Titta på plantan, om den inte slokar öka från tiden med en minut åt gången upp till 10 minuter.  Repetera detta en gång i veckan.

Det ultimata är 1 minut till och 2 minuter från under de 2 första veckorna.

1 minut till och 3 minuter från under bladsättningen

1 minut till och 10 minuter från under blommningen.

När man planterar sticklingar i en aeroponic chamber måste de vara konstant fuktiga och de måste täckas för att hållas fuktiga. När de väl har rotat sig skall de ha näring.

Närings intervallen delas in i vegetativ och blommnings stadiet genom rot temperaturen. I blommningsfasen är det viktigt att rötterna får tillräckligt med syre.

Tänk på att i ett Aerophonic system så skall EC vara något lägre koncentrerat då rötterna har lättare att ta till sig näringen.

Dag och Natt
De flesta plantor tar upp näring både på natten och dagen. Men mest näring tas upp under kvällen och natten då temperaturen sjunker och vid lägre temperatur kan rötterna tillgodogöra sig mer näring detta sker i större utsträckning med tomater och gurkplantor.

Under dagen då det är varmare minskar fotosyntesen och avdunstningen och näringsupptaget minskar. Calcium tas upp under natten då rottrycket kan suga upp mera vatten.

Rotsystemet jämförelse
I ett Deep Flow system ligger rötterna kontinuerligt i vatten eller i ett droppsystem har rötterna inte ett så förfinat och mera brunaktigt rotsystem i jämförelse med ett Aeroponic system.

Aeroponics - Misting Frequency and The Root Systems

Introduction:
Aeroponic systems, which use a mist of nutrients over the plant roots, inside a growing chamber. Producing faster growth rates, high yields and healthy roots. As long as the plant rooting chamber is being kept between 17C – 22C consistently. Some of the more sophisticated commercial greenhouse systems are temperature linked. The temperature is continually monitored in the root chambers, when pre-set temperature is triggered the mister system is activated to bring temperatures down.

Simple Misting Time:
One method of delivering nutrient spray in commercial aeroponic systems is the `regular, intermittent misting cycle’. This is a burst of nutrient solution, misting 3 minutes every 5 minutes. By using this technique, which does not change during the life of the crop, the misting cycle never causes the plant’s roots to dry out. The emphasis here, is on regularly delivery fresh aerated, temperature adjusted nutrient to the root zone.

Continual Misting with Proper "Oxygenation":
With proper oxygenation nutrient solution in the aeroponic growing chamber, the plant root system will not become `water logged’ or cause `root rot’ problems. Unless the root system is damaged with presence of large numbers of root pathogen spores or bacteria, nutrient deficiencies or toxicity's or other undesirable elements contained within the water. Proper oxygenation in aeroponic system is successfully researched in commercial production of many plants including large medicinal plants at the University of Arizona’s research faculty. The extensive plant root systems on continual misting cycle with proper oxygenation nutrient solution produces extremely healthy roots and high yields of plant material. Continual misting eliminates the problems of roots drying out between misting cycles and is one way of ensuring temperatures in the root zone stay stable and do not fluctuate. Rapid fluctuation in root zone temperature is extremely detrimental to most plants and results in `thermal shock’ weakening the roots, slowing nutrient and water uptake, and predisposing the plants to pathogen attack.

Nutrient uptake - Day and Night:
Most plants take up nutrients by both day and night. With nighttime being the more dominant side. Commercial hydroponic growers of `heavy feeder’ crops such as cucumbers and tomatoes, experience higher nutrient uptake in the evening and into the night as the temperatures cool down the plants are able to take up more water and nutrients through increased root pressure and more suitable environmental conditions. Warmer conditions during the day, the plant will shut down photosynthesis and transpiration and thus reduce nutrient uptake, and will then feed rapidly in the evening as conditions become cooler. Calcium is taken up during the night when root pressure allows more water uptake and transpiration within the plant, carrying with it calcium into plant tissue.

The fact that plants do take up sometimes large amounts of nutrient at night, and still need high levels of oxygen for root respiration means that aeroponic units should be operating at night as during the day. The fact that cooler conditions at night mean the roots will stay moist longer between misting is not enough reason to stop or reduce the frequency of misting at night. If a misting cycle of on for 2 minutes, off for 1 hour may in fact keep the roots suitably moist. During this off time, the thin film of nutrient which coats the roots has become `stale’ that is deficient in dissolved oxygen. Which may have become deficient in certain mineral ions, and may have built up excess levels of plant waste gases and metabolite by products, which need to be flushed from the root system. The ideas of aeroponics is not just to supply oxygen rich nutrient and keep plants roots moist, but to deliver mineral irons for plant uptake, wash away any root waste products or gases and provide regular supplies of fresh nutrient. Test after test has shown that plant still needs nutrient turnover to feed well and certainly still need high levels of oxygen. Under warm night conditions, keeping up a frequent misting is vital as even higher levels of dissolved oxygen in the root zone will be required and the plants will still be taking up large volumes of water and nutrient ions.

The Need for Tweaking:
Aeroponic timer units allows the grower to adjust the frequency of the on/off misting or spraying cycle as well as how long the roots are misted for. FHD has discovered that by changing the cycle timer during the plant stages of life, we received overall better production without adding higher cost in the systems. This idea is based on applying more oxygen to the root system than the regular intermittent misting cycle. When using this type of system the following points should be taken into account.

1. There is not one set ideal misting program, the amount of nutrient mist time required, is largely depended on the plant, stage of development and more importantly the temperature in the root chamber during the plant stages.

2. Each growing environment is different. The need for experimenting is crucial in receiving eXtreme harvest. Take your time, set your timer 1 minute on and 1 minute off. Then watch the program in action allowing to repeat its self a few times making sure the plant leaves don’t start to wilt from lack of nutrient mist. If no sign of wilting, increase off time for a minute. Continue until desired setting is reached or 10 minutes is reached. Repeat this programming once a week for that growing week. Ultimate would be 1 minute on and 2 minutes off, for first 2 weeks of vegetative stage. Then moving to a 1 minute on and 3 minutes off after shading the growing chamber and the whole duration of flowering a 1 minute on and 10 minutes off.

4. The major benefit of an adjustable misting program is its flexibility in the growing stages of the plant. When propagated in an aeroponic chamber, newly clipped clones need to be constantly misted until rooted with a dome on top to trap humidity to the plant leaves. Once rooted, the root system needs nutrients. The nutrient interval cycles are determined in vegetative and flowering stages by root temperature. As the plant matures, the plant leaves will begin to shadow the growing chamber, reducing temperature, allowing decreasing misting time. By utilizing this procedure, the plant is allowed more oxygen intake to the root hair between feedings, achieving faster and bushier growth. In flowering, the importance of oxygen intake to the root system is staggering. Plants will go from looking beautiful to looking sick and death is inevitable from oxygen starvation.

5. Always keep a close eye on the root system inside an aeroponic chamber - even slight drying of a portion of the root system will result in tissue damage and could lead to pathogen attack.

6. Make sure to use a quality sediment free nutrient, as it's very important not to have a mister plug up. Remember that in aeroponics, nutrient solution needs to be less concentrated, than other soil-less systems as the roots intakes the nutrients much more easier.

Root Morphology and Root Health:
Plant root systems are capable of adaptation to the conditions in which they are grown, and this is commonly seen in all types of hydroponic systems. The roots, which end up continually submerged in a `deep flow’ or constant drip systems will commonly be long, thin, relatively unbranched seem to be lacking in fine, fluffy root hairs, will be yellowing or brown in color. These have become adapted to submerged conditions and have become specialized in absorbing minerals and oxygen in the liquid nutrient (as dissolved O2). The roots which develop up above the flow or pond of nutrient are typically whiter in color, shorter, but more branched and often contain masses of very fluffy, fine, bright white root hairs. These roots are adapted to drier conditions although the air surrounding is still moist enough to prevent desiccation -they are specialized in absorbing water and nutrient from very fine films of nutrient and oxygen from the air. Such specialized roots take a few days, sometimes weeks to develop, and if suddenly the environment is changed, they will suffer a severe set back and some roots will die off, although the rest will adapt to the new conditions over time.

This is why in an aeroponic system, if the root system is continually experiencing a `off’ cycle between misting, the root that will develop will be specialized to survive these conditions. Typically they will be the white fluffy root hairs which provide a very large surface areas to absorb water and nutrients from a very thin film which coats them. Often root systems in `hydroponic' systems will be extremely long, thin and brownish in color when the water cycle is frequent. High temperatures result in brown, thinner roots, but these are just as healthy as the fine, white fluffy roots found in other systems. The only time root systems should be of concern in aeroponics, is when there is obviously something wrong such as root disintegration or rotting, bacterial slimes or fungal growth. Pathogens can certainly attack aeroponically grown roots, however this is most common where the root system has dried out (even slightly). Other common problems are become stressed (such as with a thermal shock), or overheated in the root chamber. All this weakens the roots sufficiently to make them very prone to pathogen attack.

Conclusion
Aeroponic systems do not confirm to one set `rule’ or `spraying program' which is optimal for all growing conditions or all plant types. It is up to the grower to decide the best `cost effective and plant growth effective cycle’ for running an aeroponic system. Generally however, more frequent misting cycles are preferred as they lower or eliminate the risk of root drying, and root water logging is usually not an issue in a well designed aeroponic system.

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