ISHS Acta Horticulturae 98: Symposium on Research on Recirculating Water Culture
THE PRODUCTION OF MICRONUTRIENT ELEMENT DEFICIENCIES IN PLANTS GROWN IN RECIRCULATED NUTRIENT FILM (NFT) SYSTEMS |
| Authors: | E.J. Hewitt, E.F. Watson |
| Abstract:
Our objectives were to test the suitability and convenience of using NFT systems based on readily available components for producing deficiencies of most of the plant micronutrients in a variety of species and to describe for diagnostic purposes some of the symptoms of micronutrient deficiencies of probable importance for crop production by NFT methods. Established Long Ashton methods were used to purify nutrient reagents and water. The plant channels (1 : 50 gradient) were rectangular section PVC rain water guttering. Polypropylene reservoirs (130L) and "header" tanks (50L) were connected to 12 mm reinforced black PVC water tubing and "Nylon" impeller magnetically coupled pumps. The flow rate in the gutters was 50 – 300 ml min-1 according to requirements. Severe deficiency effects causing death of most plants in a few weeks were produced by omission of iron, boron or copper with tomato, dwarf french bean, cucumber, spinach or green pepper sown in the treatments. Omission of manganese induced severe symptoms and death in 4 – 8 weeks in most plants and molybdenum deficiency induced typical symptoms generally and death of spinach, but beans with large seed reserves were practically unaffected. Zinc deficiency was delayed by nutrient contamination but older plants showed characteristic symptoms. Brassicas, legumes and other crops used above, when transplanted from complete nutrient, showed no delay in appearance of iron deficiency. Boron, copper and molybdenum deficiencies were mostly greatly delayed but manganese and zinc deficiencies appeared more quickly. | |
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