ISHS Acta Horticulturae 554: World Congress on Soilless Culture: Agriculture in the Coming Millennium
EXPERIENCE WITH IRON NUTRITION IN NFT CULTURE OF BUTTER-HEAD LETTUCE USING POLYPHOSPHATES AND LIGNOSULFONATES |
| Authors: | A. Demeyer, N. Ceustermans, F. Benoit, M. Verloo |
| Abstract:
The results of three years research on non-synthetic Fe-chelates for NFT lettuce are reported. Polyphosphates and lignosulfonates were compared with a commercial chelating agent (HEDTA). Results of different growth experiments showed that iron-polyphosphates replaced synthetic chelates without any adverse effect on plant quality, as evidenced by analyses of total plant nutrient contents, plant iron (II) and plant pigments. Supply with polyphosphates increased the phosphate concentration in the nutrient solution, but did not result in higher plant P content. Excessive dosage with polyphosphates should be avoided to prevent precipitation with calcium. The results from different growth cycles with Ca-lignosulfonates showed that lignosulfonates effectively replaced synthetic chelates. However the high Ca-concentration in this product induced nutrient unbalances. Supply with Fe-lignosulfonates could solve this problem. Excessive Fe supply is inevitable, regardless of the form in which it is supplied | |
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