Hydroponic growing of lettuce (Lactuca sativa L.) using a thin layer system with different substrates
1998
Osvald, J. | Gantar, M. | Petrovic, N. (Ljubljana Univ. (Slovenia). Biotechnical Fac., Agronomy Dept.)
In the experiment, which took place on the experimental field of the Bio-technical Faculty in Ljubljana from the end of September 1992 until February 1993, we have compared the hydroponic growing of lettuce (cv. 'Lusiana') on four different substrates (vermicu-lite, rockwool - 'Agrotervol', compost, and a mixture of compost and peat) with classic growing in soil. The highest average weight (139.9 g/plant) was measured in the mixture of compost and peat. The average weight in the compost was 129.3 g/plant, in soil 95.0 g/plant, in rockwool 72.1 g/plant and in vermiculite 64.4 g/plant. Plants grown in vermiculite and rockwool had a much greater weight on the upper side of the parcel - at the place where we had been adding nutrient solution - compared with the lower side of the parcel. Measurement of nitrate on the upper side of the parcel registers a higher contain of nitrate in leaves than in substrates. The highest average nitrate content was measured in plants grown in soil, while the lowest average content was recorded in plants grown in rockwool and in the mixture of compost and peat.
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