Purslane is an excellent source of omega-3 fatty acids, amino acids and vitamins. The aim of this research was to study the effect of different nitrogen levels and NO 3 − -N/NH 4 + -N ratios in the nutrient solution on the yield and on the oxalic acid content and fatty acid profile in purslane grown in a soilless culture system. Two experiments were carried out to test different levels of nitrogen: (1) 8-12-16 mmol L −1 and (2) 0-12-24-36 mmol L −1 . A third experiment was carried out maintaining the N level fixed (12 mmol L −1 ) but varying the NO 3 − -N/NH 4 + -N ratio: 60:40, 40:60, 0:100. The results indicated that plants grew with increasing nitrogen level up to 36 mmol L −1 . Nitrogen supplied in both NO 3 − and NH 4 + forms produced bigger plants than N supplied in NH 4 + form only. Nitrogen did not significantly influence the polyunsaturated fatty acid content in the canopy. Significant trends were found for α-linolenic acid (LNA; 18:3 n-3) and linoleic acid (LA; 18:2 n-6), indicating a favorable accumulation of omega-3 fatty acids with increasing N; palmitic acid decreased by increasing N and by switching the NO 3 − /NH 4 + ratio towards the NH 4 + level in the nutrient solution, but using 0:100 NO 3 − /NH 4 + , decreased plant quality. Increasing N lowered oxalic acid production and palmitic acid content, enhancing purslane nutritional quality. Keeping a high N level in the nutrient solution with a 40:60 NO 3 − /NH 4 + ratio would give the best results in terms of yield, oxalic acid concentration and fatty acid profile.

Rocket is traditionally cultivated in soil and commercialized either as fresh or as ready-to-eat produce. This leafy vegetable is often commercialized fresh, cut, washed, conditioned in packages as ready-to-eat food, giving added-value to the fresh products. Soilless culture system (SCS) allows to control growth factors and clean leaf production, easing and shortening postharvest handling in process industries. A comparison between the traditional culture system (TCS) and a SCS was effected, with two plant densities (1067 and 2134 plants/m 2). TCS was simulated in polystyrene trays filled with local soil and peat (1:1 v/v), overhead irrigation and weekly fertilization. For SCS 40cell trays were filled with 1:1 perlite and peat, seeded and floated in a nutrient solution during plant growth. Fresh leaf production was significantly influenced by culture system x plant density. Rocket grown with SCS produced about 75% more than plants grown with TCS. The plants grown in SCS with the highest plant density gave the greatest production (2182 g m-2). Nitrate leaf content was significantly influenced by the culture systems. The leaves of plants grown with TCS contained less NO 3 than those grown with SCS, in a ratio of 1:1.6. With both culture systems the nitrate content was much lower than 2500 mg kg-1 f.w., which is the maximum content allowed by EU regulation for lettuce. In this experiment SCS allowed to enhance earliness: in fact, SCS produced marketable and ready-to-eat rocket in 70 days, while TCS would require extended growing period.

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