In thisstudy, the growth and yield ofleafy vegetableson the hydroponic system ofnutrient
film technique with a heated nutrient solution was compared with a non-heated solution.
The study took place from November 2019 to March 2020 in the greenhouse of the
Biotechnical Faculty in Ljubljana. Different types of leafy vegetables were included:
lettuce 'Posavka' and 'Vegorka', leek 'Lancelot', curly mustard 'Mustard Giant grün' and
mizuna mustard 'Mizuna rot' and 'Mizuna grün'. At harvest plant height, number of leaves,
stem length and diameter were measured and fresh mass was weighed. The results for leek
showed that plants grown in the heated solution were taller, had higher fresh weight, more
leaves and longer roots than in the unheated solution. In the heated solution the calculated
yield was 15.2 t/ha and in the unheated solution was 9.8 t/ha. Lettuce plants of both
varieties had more fresh mass and a larger rosette diameter in the heated nutrient solution
compared to unheated solution. The calculated yield in the heated solution was 16.4 t/ha
for 'Vegorka' and 13.6 t/ha for 'Posavka', and in the unheated solution 11.1 t/ha for
'Vegorka' and 8, 8 t/ha for 'Posavka'. In the case of curlymustard, heating the solution only
increased the fresh weight of the plants, and the calculated yield (39.2 t/ha) was higher
than in the unheated solution (37.2 t/ha). For cutting mustards, the heated nutrient solution
had a negative effect on the growth of 'Mizuna rot' plants, the plants in the unheated
solution had 20% more leaves and were taller compared to the plants with the heated
solution. The calculated yield of curly mustard was 8.9 t/ha in the unheated solution, and
4.2 t/ha in the heated solution. The variety 'Mizuna grün' had more fresh weight, taller
plants and more leaves per plant in the heated solution than in the unheated one. The
calculated yield per area was 33.6 t/ha in the heated solution and 19.8 t/ha in the unheated
solution.
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