The present study deals with biochemical and physiological methods for assessment of the optimal nutrient supply for the growth and development of garden rocket (Eruca sativa Mill.), edible vegetable. Two nitrate (0.3; 0.6 g N dm^-3 of medium) and three potassium doses (0.3; 0.6; 0.9 g K dm^-3 of medium) in the form of sulphate or chloride were examined. At the higher nitrate dose and the sulphate form of potassium the intense green colour of leaves, higher content of nitrates, flavonoids, L-ascorbic acid and lower carbohydrates content correlated with elevated growth parameters, e.g. the number of leaves and partially plant fresh weight. The proline and anthocyanin contents weakly diversified the nutrient supply. Despite the lack of modification in the photosynthetic pigment concentration, the chlorophyll fluorescence parameters were significantly improved when the higher nitrate dose accompanied the sulphate form of potassium (higher values of fluorescence decrease, maximum quantum efficiency of PSII photochemistry in the dark-adapted state, photochemical quenching and lower values of the fraction of absorbed light energy not used for photochemistry). The biochemical and photosynthetic parameters corresponding to the morphological characteristics (leaf colour, number of leaves and plant fresh weight) indicated that better nutrient conditions were provided to plants under the combined fertilization of the higher nitrate dose and the sulphate form of potassium.

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