Extraction and Nutrient Efficiency during the Vegetative Growth of Tomato under Hydroponics Conditions

This work was carried out in order to assess the extraction and nutrient efficiency for macroelements (N, P, K, Ca, Mg) of tomato (Lycopercicon esculentum Mill.) during the vegetative growth (1-74 days after transplanting, DAT) in greenhouse hydroponics grown during autumn and winter. Dry matter production (g plant(-1)) and nutrient (N, P, K, Ca, Mg) contents in roots, stems, leaves and fruits were measured, as well as nutrient stored in substrate (tuff) and nutrient leached with water pot drainage. Results showed an increasing demand in nutrient extraction during the vegetative growth in the order P<Mg<Ca<K<N and presented the highest nutrient uptake rate at 59-74 DAT with 47.6, 152.9, 208.3, 246 and 390.9 mg plant(-1) per day, respectively. Roots and leaves produced both the highest dry matter accumulation (39.9 and 37.1 g plant(-1)) and the highest nutrient extraction (55.14 and 51.19 g plant(-1)). Nutrient efficiency was low at the beginning of plant growth: at 40 DAT only 25.7% N (in relation to supplied nitrogen in the nutrient solution), 9.3% P, 11.2% K, 6.5% Ca and 19.7% Mg were absorbed by plants, but at 74 DAT nutrient efficiency increased to 80.3, 38.3, 39.3, 24.3 and 59.6%, respectively. The percentages of nutrient retention in growing media at 74 DAT were N: 1.9, P: 54.8, K: 35.1, Ca: 38.8 and Mg: 26.5; meanwhile nutrient leakages in drainage water (26% in relation to total water supply) were N: 17.8, P: 6.8, K: 25.6, Ca: 36.8 and Mg: 13.9%. These values of nutrient efficiencies by tomato indicate that the concentration of nutrient solution used in the vegetative stage should be adjusted during autumn-winter tomato cropping.