ISHS Acta Horticulturae 779: International Symposium on Growing Media
NUTRIENT CONCENTRATIONS OF PLANT TISSUES OF GREENHOUSE CROPS AS AFFECTED BY THE EC OF THE EXTERNAL NUTRIENT SOLUTION |
| Authors: | C. Sonneveld, W. Voogt |
| Keywords: | EC, nutrient uptake, osmotic effects, osmotic adjustment, uptake concentration |
| Abstract:
This paper reports osmotic effects from a series of experiments where greenhouse crops were grown in substrates with different EC values of the nutrient solution. Results of yield characteristics were published elsewhere: in the present paper, the nutrient uptake in relation to the EC will be discussed in the light of growth of lily, lettuce and kohlrabi. The crops were grown in substrates within a circulation system and thus, the water absorption of the crops could be precisely determined. The nutrient absorption was determined by tissue analysis. For lettuce whole heads were sampled and analysed; for lily, bulbs and leaves and for kohlrabi, tubers and leaves were sampled and analysed separately. The results showed a strong increase of plant nutrient concentrations in the EC-domain until the optimum growth response of the crops. Higher EC values did not affect the plant nutrient dry matter concentrations seriously, except for K concentrations of the lily crop. Calculations showed that the K concentration in the plant sap played an important role in the osmotic adjustment of the different crops to high external concentrations. The uptake concentrations of the different crops were presented and discussed in relation to the EC value in the external solution. External nutrient concentrations and plant nutrient concentrations in relation to optimum yield are presented. Calculations are made of the nutrient efficiency of a system with drainage to waste compared with a system with reuse of drainage water. | |
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