In a graduation experiment conducted from March to September 2023 in the greenhouse
of the Laboratory Field of the Biotechnical Faculty, the production of lettuce (Lactuca
sativa L.) on a hydroponic system and in soil. The lettuce variety 'Joliac' was icluded
and growth and development were monitored over four growing period, from May to
September. The experiment was designed in four replicates. Each replicate consisted of
10 plants on the hydroponic system and 12 plants on the soil system. Soil cultivation
was carried out on a covered soil, where plants wereirrigated with a drip irrigation
system. For the hydroponic system, a NFT (Nutrient Film Technique) system was used.
Results showed that the expected yield of rosettes was higher for the hydroponic system,
3,8 kg/m2 (in the first term) and 2,5 kg/m2 (in the same term) for the plants grown in
soil. In spring, the growing period of the plants was 4 weeks for the hydroponic system
and 6 weeks for the plants grown in soil. In summer, however, the plants on the
hydroponic system needed 2 to 4 weeks to develop technologically mature rosettes, and
4 to 5 weeks for the soil-grown plants. The dry matter content of lettuce plants grown
in summer was 12-14% and did not vary according to the production system. However,
in spring , soil-grown plants had a higher proportion of dry matter (18%) compared with
hydroponically -grown plants (9%). The nitrate content of hydroponically grown lettuce
was highest in the first two terms (May-June and June-July), ranging from 2700 mg/kg
to 2800 mg/kg fresh weight, and lower in the third and fourth terms (2000 mg/kg fresh
weight and 1000 mg/kg fresh weight, respectively), and did not exceed the legal limits.
When grown in soil, lettuce contained between 360 and 840 mg nitrate/kg fresh weight.
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