ISHS Acta Horticulturae 98: Symposium on Research on Recirculating Water Culture
THE GROWTH AND MINERAL COMPOSITION OF SUNFLOWER PLANTS, HELIANTHUS ANNUUS, UTILIZING NITRATE- OR AMMONIUM-NITROGEN WHEN GROWN IN A CONTINUOUS FLOWING CULTURE SYSTEM. |
| Authors: | A. Kurvits, E.A. Kirkby |
| Abstract:
Sunflower plants (Helianthus annuus) were grown using a continuous flow nutrient system in an experiment in which nitrogen was supplied as nitrate or ammonium, and the pH of the nutrient medium controlled. The experiment revealed that there was little difference in growth between the two nitrogen treatments. This finding contrasts markedly with our own and other workers' observations that in static water cultures, NO3-N is very often a preferential source for plant growth. The concentration of K, Ca, Mg and Na, in the dry plant material, were all higher in the NO3-fed plants, but for P the converse was true. The total uptakes of K, Ca, Mg, Na and N (mg per plant) were also higher in the NO3-fed plants whereas for P, again, the reverse was the case. The mean rates of uptake of K, Ca, Mg and Na during the intervals between harvests, expressed per unit root length at each harvest, were all higher for the NO3-fed plants. For P, however, the rate of uptake was higher by the NH4-fed plants. The results are discussed in relation to the comparative influences of nitrate and ammonium nutrition on ion uptake, metabolism and plant growth. | |
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