Aeroponic system of plant culture

 

Q. What is aeroponic system of plant culture? Diagrammatically represent the system.  2+6                       

 

                          Aeroponics: Aeroponics is defined by the International Society for Soilless Culture as “a system where roots are maintained in an environment saturated with fine drops (a mist or aerosol) of nutrient solution” . In other words, instead of planting crops directly into the soil or media or growing them in a nutrient rich liquid solution, aeroponics relies upon applying a fine mist of nutrients and water directly onto the roots themselves. The plant is typically suspended or supported in some manner and the roots allowed to grow freely in the air inside a closed chamber without contact with any substrate.

 

                          In these containers roots can find the best condition regarding oxygenation and moisture. These conditions allow for better plant nutrition assimilation in a more balanced way, with consequential faster development of the cultivated plants .              

 

                           An aeroponic system was developed at the Cabot Foundation Laboratories during 1973-1974 as a method for studying root nodules on peas. The present system is the result of a long series of empirical changes and improvements. The present principle of this technique is to grow plants with their root systems exposed constantly to a nutrient mist.

                    

Instrument and machinery: An excellent feature of this system for growing plants in the greenhouse is that it is simple to operate and involves no complex machinery.

 

Container : A box (container) in which the plants are grown is made. The top of the box consists of  holes  at which  plants are to be spaced. “Traditional” aeroponics systems use a horizontal trough for supporting the plants. To make more efficient use of space, a modified stack arrangement will be used instead. Commonly available materials will be used where possible to minimize costs.

The basic structure would consist of 3” dia. PVC piping constructed in a “lean-to” fashion. Thin, styrofoam sheets (“blue board”)

cut into 2’ x 2’ panels would be used to support the plants. Pre-punched holes of 1-2” dia. Would be made to hold rooted seedlings. Spacing of the holes would be crop dependent. Therefore, a number of different crops could be grown simultaneously (assuming their nutrient requirements were similar).The panels would be held in place by brackets or clips, to make removal easier. This would allow for easy access to plants for harvesting as well as for viewing the developing roots. The lower frame would be covered on all sides by black polyethylene plastic or blueboard, to contain the mist spray and help maintain a high humidity level required in the root zone. The misting nozzles would be installed at the base of the frame. To allow for nutrient and water recycling, a plastic liner would be mounted just below the misting heads and at the same.

Impellor system: The impellor system is also required. It is composed of 3 parts: the motor, he shaft, and the spinner. The motor turns the spinner. The shaft is solid stainless steel, attached to the motor at one end by set screws and to the plastic spinner at the other.  The spinner, made  up of light durable plastic, creates the mist in which the plant roots grow. The tip of the spinner dips into the nutrient solution sucking it up by centrifugal force. Plants should not be placed closer than 25.4 cm from the motor on any side. Plants placed closer than this will not receive enough mist to sustain growth in the early seedling stage.

 

Procedure:

1.    Plant containers can be mounted on top of one another and because they are light and handy, they can be easily moved according to agricultural needs. Numerous plants are mounted in vertical columns within a greenhouse or shade house space. Nutrients are allowed to trickle down through the growth columns.

 

2.    Young plants are placed at the highest level of the growth column. Afterwards they are progressively lowered utilizing a rotational mechanical system. With the rotation periodically repeated, this permits constant production without any interruption. Because Most agricultural plants need a direct exposure to the sun during the first vegetative development. Afterwards this direct exposure is no longer relevant. Based on this observation, plant containers are periodically displaced.

 

3.    Plant nutrition is supplied into a closed circuit. Consumption is consequently limited to only the quantities absorbed by the plants, allowing for substantial water savings. For example: to produce a kilogram of tomatoes using traditional land cultivation requires 200 to 400 liters of water, hydroponics requires about 70 liters, aeroponics utilizes only about 20 liters.