ISHS Acta Horticulturae 82: Symposium on Production of Protected Crops in Peat and other Media
SOME ASPECTS OF THE NUTRITION OF TOMATOES GROWN IN RECIRCULATING SOLUTION |
| Authors: | G.W. Winsor, D.M. Massey |
| Abstract:
The responses of tomato plants to nitrogen and potassium have been studied in nutrient film culture. A series of experiments collectively covered the ranges 10–320 ppm N and 20–375 ppm K. Varying proportions of ammonium-N (25%, 10% and nil) were included in order to assess the potential for pH control. High nitrogen (275 ppm N) including 25% NH4-N had little effect at first but ultimately reduced yield, fruit size and root growth (P<0.01), probably because of excess ammonium-N and acidity. A relatively low nitrogen concentration (35 ppm) sufficed for maximum growth when NH4-N was included at 10% of the total. Nominal concentrations of 10 ppm N and 20 ppm K both proved deficient, associated with nutrient depletion in the solutions. With small pumps incorporated to help maintain nutrient concentrations, no differences in appearance or early yield were found over the range 10–320 ppm N, supplied as nitrate. Plants thus grow satisfactorily in nutrient film culture at concentrations of nitrogen far below those normally recommended for conventional solution culture. The degree of depletion of N and K along a gully was shown to be significant statistically but too small to be of practical importance. | |
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