The effect of N and NaCl on growth, yield, and nitrate content of salad rocket (Eruca sativa Mill.)

ABSTRACT

Hydroponic production of rocket as a salad vegetable has become increasingly important in recent years. Rocket is known to be a high nitrate (NO₃^–)-accumulating vegetable, which can be grown throughout the year. In the present study, rocket was grown in a floating hydroponic system at three levels of nitrogen (N) and sodium chloride (NaCl). The highest yield was obtained at 14 mM N, whereas the yield was lower at 20 mM and 40 Mm NaCl. Leaf elongation was more sensitive to salinity than leaf differentiation. Adding NaCl to the nutrient solution increased the relative chlorophyll content. Na⁺ and Cl^– concentrations increased as salinity increased. NO₃⁻ levels in fresh biomass increased with increased amounts of NO₃⁻ in the nutrient solution, and plants at 18 mM N were able to maintain a higher NO₃⁻ : Cl⁻ ratio than those at 10 mM N.

KEYWORDS:

• chlorides
• floating system
• salt stress
• nitrate
• shelf life