A model relating the maximum nitrate inflow of lettuce (Lactuca satvia L.) to the growth of roots and shoots |
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Authors: | B. Steingrobe M. K. Schenk |
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Affiliation: | (1) Institute of Plant Nutrition, Technical University of Munich, D-85350 Freising, Germany;(2) Institute of Plant Nutrition, University of Hannover, Herrenhäuser Str. 2, D-30419 Hannover, Germany |
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Abstract: | The net inflow of nitrate can be calculated from the nitrate concentration at the root surface by means of the Michaelis-Menten equation. Because of maximum inflow (Imax) is not constant but varies with plant age and growing conditions, a model for calculating Imax during plant growth was derived. Lettuce was grown in nutrient solution. Variations in temperature, radiation and plant age were used to vary growth rates and N-demand of plants. There was a linear relationship between relative growth rates (RGR) and maximum nitrate inflow (Imax), that could be described by the following regression function: Imax = 0.24 + 6.57 RGR. A residual analysis showed a further influence on Imax from the root:shoot-ratio (RSR), the effects of which could be accounted for by including an e-function in the relationship: Imax = (0.27 + 10.63 RGR) e(–0.0017 RSR). This model for calculating Imax was validated in two further experiments. |
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Keywords: | lettuce maximum inflow (Imax) model nitrate relative growth rate root:shoot-ratio |
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