ISHS Acta Horticulturae 548: International Symposium on Growing Media and Hydroponics
QUANTITATIVE NUTRIENT MANAGEMENT AT LOW CONCENTRATION CONDITION IN NFT SPINACH CULTURE |
| Authors: | T. Maruo, H. Hoshi, M. Hohjo, Y. Shinohara, T. Ito |
| Keywords: | Quantitative nutrient management, NFT, closed-recirculating system, low concentration level, Spinacia oleracea L. |
| Abstract:
A new quantitative nutrient management (QNM) method employing a low concentration nutrient solution was investigated in Nutrient Film Technique (NFT) spinach (Spinacia oleracea L.) culture. Spinach seedlings were planted in a closed-recirculating NFT system in which channels were modified for low nutrient concentration. The first of two experiments used rainwater as the initial solution (starter solution). Three different amounts of nutrient were then supplied via the QNM method on the basis of estimated daily nutrient uptake. In the second experiment the QNM method with the three different concentrations of starter solution was applied from beginning. Experimental results were compared with those of the conventional EC control method (EC=2.7 dS.m-1). Although the initial plant growth was retarded slightly with the QNM, there was no significant difference in marketable weight at harvest between plants grown using QNM and conventional methods. The QNM reduced nitrate content and increased ascorbic acid content in the edible part of spinach plants. One advantage of the QNM method is that it allows for the maintenance of nutrient solutions at low concentrations. This reduces nutrient emissions through the renewal of nutrient solution. The method also makes it possible to control the amount of nutrients absorbed by the plants without disturbing plant growth or reducing yield. A spinach plant of commercial size (28g fresh weight) absorbed approximately 8.5 me.cell-1 of NO3-N during culture. | |
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