ISHS Acta Horticulturae 150: International Symposium on Substrates in Horticulture other than Soils In Situ
THE USE ON AMMONIUM - N FOR CONTROLLING PH AND IRON AVAILABILITY IN RECIRCULATING NUTRIENT SOLUTIONS |
| Authors: | Edward W. Johnson, P. Moore |
| Abstract:
Ferrous sulphate was added at weekly intervals to supply 3 mg/l Fe to recirculating nutrient solutions containing ammonium-N at 0,6 and 12% of the total nitrogen in solution. Lettuce grown with no ammonium-N in solution soon developed chlorosis of the youngest leaves typical of iron deficiency, and growth was severely restricted. The symptoms spread eventually to the 6% treatment but the 12% treatment remained virtually free of any chlorosis. Average fresh weight per lettuce was 182, 230 and 264 g in the 0,6 and 12% treatments respectively. The 'active' iron contents in the leaf were assessed by the method of Katyal and Sharma. Ammonium-N increased the 'active' iron in all leaves and not just the youngest leaves. | |
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