Reduce nitrate uptake
From the September 2008 edition of Agriculture Today.
Asian vegetables are being put on a weight loss program to improve their quality, extend their shelf life and reduce their growing costs.
Research at Gosford Horticultural Institute aims to reduce the nitrate concentration of a range of vegetables grown in Australia.
"There is not much information available about appropriate fertiliser strategies for Asian vegetables grown in soil or in hydroponics," Gosford plant physiologist, Dr Sophie Parks, said.
"We know that about half of the leafy Asian vegetables purchased in the market place have an undesirably high nitrate concentration.
"This is likely to be due to the naturally high uptake of nitrate by Brassica vegetables, to which most Asian leafy vegetables belong, combined with excessive use of fertilisers in the production of these vegetables.
"Excessive application of nitrogen fertilisers to horticultural crops is a demonstrated problem in Australia where high losses of nitrate have been recorded from market gardens."
NSW Department of Primary Industries is undertaking the project, with $215,000 funding from Horticulture Australia and Ausveg over three-years.
Dr Parks has begun work with several greenhouse trials of plants, feeding them various nitrate levels.
Not that you would know which is which, as the plants are still thriving regardless of which tucker mix they are receiving.
"Efficient nutrient management in the production of leafy Asian vegetables is important to minimise production costs, prevent nutrient runoff and to ensure that the produce is of a high quality," Dr Parks said.
"Excessive nutrients can reduce vegetable quality, for example, lower the vitamin C concentration and increase the risk of soft rots.
"Vegetable quality is also compromised as increasing application rates of nitrogen-content fertilisers can increase the incidence and severity of bacterial soft-rot."
The nutritional requirements for a range of species will be determined through experiments.
Consultation with commercial laboratories will also assist in the development of protocols for plant analysis.
"Protocols for simple on-farm leaf tests will be developed using existing nitrate tools on the market," she said.
Farmers and agronomists will be trained in simple test protocols and on interpreting test results to improve crop nutritional management.
"If we can reduce the amount of nitrate input we will end up with a healthier product at a cheaper cost to the grower," Dr Parks said.
Dr Parks said the European Community had limits on fresh nitrate concentrations in some leafy vegetables such as spinach and lettuce, but there were no limits yet in Australia.
"Food Standards Australia and New Zealand (FSANZ) will soon publish a dietary exposure assessment and risk characterisation of nitrate and nitrite in foods in Australia and this may affect the introduction of any regulations," Dr Parks said.
"Therefore the vegetable industry’s action on nitrates in vegetables with this project is timely."
Contact Sophie Parks, Gosford, (02) 4348 1914.
