PALMERSTON NORTH - A sophisticated system of growing medicinal herbs in a soil-free environment is being fine-tuned at Massey University.
Horticultural science lecturers Bruce Christie and Mike Nichols say growing herbs and other plants with "aeroponics" produces better crops more quickly and easily than conventional growing methods.
A more sophisticated form of
hydroponics, aeroponics is largely unheard of in New Zealand, but has been used commercially for several years in Singapore for growing lettuce and strawberries.
It has also been used experimentally in the United States and Israel.
It is similar to hydroponics, in that the plants are suspended in an enclosed growing chamber, but rather than being immersed in a growing solution, the roots are briefly sprayed with a fine mist of nutrients and water every few minutes. The solution is made up of about 15 essential nutrients and trace elements which is all the plant needs to grow.
And because the solution is recirculated throughout the chamber, there is no waste. About 50 litres of the nutrient-rich water can keep a whole system of plants alive.
Dr Nichols said good root activity was the key to plant growth. Roots needed plenty of oxygen, of which they received little when immersed in water or soil. Changes in water and soil temperature could also affect growth.
Because the roots of aeroponically grown plants were left to dangle freely in the air, they had access to all the oxygen they needed, he said.
The scientists also had the ability to manipulate the temperature of the spray solution, in order to speed up or slow down the rate of growth.
Dr Nichols said aeroponics was quite possibly the ideal method of growing plants, because leaves, fruit and roots could all be harvested easily, without destroying the plant. As long as they kept providing the nutrient spray, the plants would live.
The aeroponics unit was set up at Massey in February. In that time it has grown tomatoes in an experiment financed by a Norwegian company, and cucumbers, and has now turned to high-value crops such as kava and medicinal herbs such as St John's wort, camomile, valerian and echinacea.
The chemical composition of the roots and tops of this first lot of herbs is about to be analysed.
The two scientists said the potential was huge for growing and harvesting the valuable roots and leaves of these plants, without destroying the whole plant.- NZPA
