Production of rocket (Eruca sativa Mill.) on plug trays and on a floating system in relation to reduced nitrate content

The effect of the growth system on the yield and nitrate content of rocket (Eruca sativa Mill.) was evaluated in two experiments. In the first experiment, different sizes of cells in plug trays and different fertilization treatments were tested. In the second, a floating system was used with different substrates and the nitrate content in rocket leaves was analysed. The size of the cells did not affect the yield of rocket significantly but the yield was notably higher (2.02 - 2.21 kg m-2) when plugs were fertigated once per week with 6:12:36 + ME + natural biostimulant in comparison with plugs fertigated only with a water soluble fertilizer (1.53 - 1.74 kg m-2). The best yield was obtained in vermiculite and perlite in 20 ml cells (2.13 and 1.89 kg m-2). The different substrates used in the floating system had no effect on the dry matter content, which was on average 13.7 % and was significantly lower than the dry matter content of leaves grown in peat (19.1 %). The nitrate content in leaves measured a day before and 10 days after the replacement of the nutrient solution with tap water, fell greatly from 4,288- 6,764 mg NO3 kg-1 FW to 52-634 mg NO3 kg-1 FW.