The concept of hydroponics is to grow seeds and/or crops without using soil as the provider of a support medium and associated nutrients. The first recorded hydroponic experiments were conducted in England in 1699 by the naturalist and geologist John Woodward. The concept of hydroponics was extended by the mid-nineteenth century by Sachs and Knop. These pioneers developed techniques of growing plants without soil. Further breakthroughs in hydroponics came from the research of Gericke who demonstrated that plants are able to grow on a commercial scale by adapting the laboratory technique of the solution culture.
Nutrients in hydroponics
In hydroculture, the plants receive their nutrient requirement by the controlled addition of minerals to the water system. One main advantage of the hydroponics approach is that it does not depend on the climate and therefore plants can be grown anytime in any location.
Our aim at Wasabi Crop Research is to grow Wasabia japonica in various greenhouse hydroponic systems to produce wasabi rhizomes for the commercial market. The proof-of-concept will be developed in various modified hydroponic and aeroponic systems based on:
Deep Water Culture: In this set-up which involves moving parts the plant roots are immersed in water containing the right concentration of nutrients. The water is kept oxygenated using an air pump to allow the roots to breathe – stopping the ‘plants’ from drowning.
Drip Irrigation: The nutrients in the water are delivered to the plants and/or seeds via a network of raised jets. This process is controlled by a pump on a timer unit. The two modes of operation are:
(a) Recovery System: when the excess nutrient solution is collected and returned back to the reservoir – the pH of the solution is susceptible to change.
(b) Non Recovery System: the excess nutrient solution does not return back to the reservoir – pH of the solution in the reservoir remains constant.
Nutrient Film Technique (NFT): This system requires a constant flow of nutrient solution. The solution is pumped from a reservoir into the growing tray which contains no medium. Essentially, the plant roots draw up the nutrients from the solution being pumped around before returning back to the reservoir.
Wicks System: The most basic hydroponic set-up consists of a series of wicks that have the ability to draw-up the nutrient solution through a variety of mediums such as perlite or gravel of coco to the surrounding plant roots.
Food & Drain: In this hydroponic system, the grow tray containing the plant roots is flooded with nutrient solution from the reservoir before draining back. This set-up is controlled by using a water pump on a timer.
Aeroponic Systems: This is the apex of hydroponic technology with the aim of growing plants in the air. In these systems, the roots are suspended in air and receive the nutrient solution by misting. The frequent misting of the roots is essential to avoid the roots from drying out. The nutrient spray pump is timer controlled to allow bursts of misting to the roots.