ISHS Acta Horticulturae 559: V International Symposium on Protected Cultivation in Mild Winter Climates: Current Trends for Suistainable Technologies
MACROELEMENTS UPTAKE AND IONIC INTERRELATIONSHIPS OF A TOMATO SOILLESS CROP IN RECIRCULATING SYSTEM |
| Authors: | A.L. Alarcón, A. Faz, C. Egea, F.J. Brañas |
| Keywords: | closed systems, mineral nutrition, perlite, water uptake |
| Abstract:
The hydric and mineral nutrition of tomato plants (cv. Brillante) cultivated on perlite bags under recirculating system is studied by following the daily net uptake by the plant of water and macroelements and the changes occurring in the nutrient and drainage solutions in order to establish the actual demand of the plant for each nutrient and the optimum ratio between the uptake of ions. In this way, we try to elaborate an adequate fertigation programme and develop strategies for the more efficient use of water and fertilisers in the conditions of Spain Southeast. The cultivation cycle was 120 days from transplanting onwards, in an autumn-winter period, and the irrigation water had an electrical conductivity (EC) of 0.9-1.5 dS/m. The total recirculating system showed a perfect viability from the technical and agronomic points of view and the final production of first quality fruits was 12.1 kg/m2. The net uptakes per plant were 59.3 litters of water, 983.5 mmol of nitrates, 127.1 mmol of phosphates, 606.9 mmol of potassium, 324.3 mmol of calcium, 110.1 mmol of magnesium and 217.8 mmol of sulphates. These amounts are equivalent to 275.4 kg/ha N, 180.0 kg/ha P2O5 and 571.8 kg/ha K2O. The closed system, in the study conditions, supposed a hydric and N-P-K fertilisers economy of about 50%. A stepwise multiple lineal regression analysis was realised to obtain the dependent of the net uptake of water and particular ions. The statistical analysis showed that there is a reciprocal relation in the uptake of nitrates-potassium, magnesium-sulphates and calcium-water pairs. On the other hand, the nitrates/potassium ratio is dependent on the elapsed cultivation cycle. The nitrates/potassium and calcium/magnesium uptake ratios initially increased constantly as the plant developed, showed the highest level in the initial harvesting period and after that decreased until the cultivation cycle finished. | |
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