Silvana Nicola 1 , Emanuela Fontana 1 , Jeanet Hoeberechts 1 , Pier Giorgio Peiretti 2 , Giovanni Battista Palmegiano 2 , Victor Cros 3 1 AGROSELVITER – Vegetables & Medicinal and Aromatic Plants Università degli Studi di Torino, Grugliasco, Italy; silvana.nicola@unito.it 2 Istituto di Scienze delle Produzioni Alimentari, CNR, Grugliasco, Torino, Italy. 3 Departamento Producción Vegetal, Universidad Politécnica de Cartagena, Cartagena, Spain When minor crops hold biofunctional foods: applying modern cultivation technology to grow Portulaca oleracea Purslane (Portulaca oleracea L.) is an herbaceous annual species with fresh succulent leaves, a high growth rate and an efficient water use. It has been eaten in salads and used as a medicinal plant. Purslane is commercially cultivated in many parts of the worlds including Asia and the Middle East. It contains many biologically active compounds, in particular it has a high percentage of omega 3- fatty acids. The quantity of omega-3 fatty acids in purslane depends on the growing conditions and the plant age. The aim of the research was to study the effect of different nitrogen levels and NO 3 - -N/NH 4 + -N ratios on the yield and on the oxalic acid content and fatty acid profile in purslane grown in a soilless culture system. INTRODUCTION OBJECTIVE Leaf and stem fresh and dry weight (FW, DW), leaf and stem area, leaf dry matter, specific leaf area (SLA=final leaf area/final leaf dry weight) and specific stem area (SSA=final stem area/final stem dry weight), SPAD degree, canopy oxalic acid and fatty acid profile* analyses Parameters measured at harvest M&M *In particular linoleic acid (LA, 18:2) and α−linolenic acid (LNA, 18:3, omega-3-fatty acid) are shown in this poster 3 nutrient solutions with different NO 3 - /NH 4 + ratios: 60/40; 40/60; 0/100. N level fixed in the nutrient solution was 12 mmol L -1 3 rd exp. 4 nutrient solutions with different N levels: 0; 12; 24; 36 mmol L -1 with 40/60 NO 3 - /NH 4 + 2 nd exp. 3 nutrient solutions with different N levels: 8; 12; 16 mmol L -1 with 40/60 NO 3 - /NH 4 + 1 st exp. Three experiments were conducted on June and July 2004 (20 days duration) at the Experimental Centre of the University of Torino (ITALY) in a glasshouse. The purslane seeds belonged to the 01-215 accession of the UPCT seedbank (Cartagena-Murcia, SPAIN). The experiments consisted of growing plants in 160-cell styrofoam trays filled with peat and continuosly floating in a nutrient solution. The experiments differed for the nutrient solution used: RESULTS 0.058 0.008 0.008 <0.001 0.016 0.006 Sig. *Within a column, values with different letters differ significantly (P=0.05) Sig. 457 0.35 b 540.9 b 68 a 48 b 714 b 0/100 12 419 0.41 a 1054.3 a 54 b 80 a 1479 a 40/60 12 386 0.43 a 1004.8 a 52 b 72 a 1380 a* 60/40 12 3 rd 0.002 0.047 0.120 0.006 0.635 0.212 N cubic <0.001 0.011 0.034 0.001 0.385 0.106 N quadratic <0.001 0.012 0.002 <0.001 0.027 0.005 N linear <0.001 0.007 0.008 <0.001 0.132 0.022 N 388 0.41 1176.7 50 91 1807 40/60 36 375 0.40 1013.9 53 79 1504 40/60 24 391 0.43 951.5 50 69 1387 40/60 12 198 0.18 142.2 95 33 274 40/60 0 2 nd 0.856 0.965 0.085 0.080 0.241 0.340 N quadratic 0.754 0.163 0.214 0.044 0.147 0.232 N linear 0.929 0.335 0.124 0.050 0.193 0.313 N Sig. 464 0.44 1136.3 53 81 1529 40/60 16 464 0.41 1025.7 52 78 1481 40/60 12 466 0.38 1268.9 57 104 1816 40/60 8 1 st SPAD SLA (cm 2 mg -1 ) Leaf Area (mm 2 /plant) Leaf DM (g Kg -1 ) Leaf DW (g m -2 ) Leaf FW (g m -2 ) NO 3 - /NH 4 + N level Exp. RESULTS 0.011 <0.001 <0.001 0.001 <0.001 Sig. *Within a column, values with different letters differ significantly (P=0.05) Sig. 0.10 b 78.7 b 59 a 24 b 408 b 0/100 12 0.11 a 153.0 a 47 b 44 a 935 a 40/60 12 0.11 a 156.0 a 45 b 43 a 967 a* 60/40 12 3 rd 0.034 0.491 <0.001 0.702 0.315 N cubic 0.002 0.024 <0.001 0.077 0.019 N quadratic 0.001 0.002 <0.001 0.006 0.001 N linear 0.001 0.006 <0.001 0.026 0.005 N 0.11 140.7 42 39 917 40/60 36 0.11 134.3 43 37 853 40/60 24 0.11 104.3 42 29 691 40/60 12 0.05 7.40 125 7 16 40/60 0 2 nd 0.041 0.671 0.013 0.216 0.574 N quadratic 0.014 0.939 0.003 0.180 0.777 N linear 0.017 0.900 0.004 0.207 0.803 N Sig. 0.11 182.0 43 51 1177 40/60 16 0.11 175.6 43 48 1122 40/60 12 0.09 183.5 50 61 1221 40/60 8 1 st SSA (cm 2 mg -1 ) Stem Area (mm 2 /plant) Stem DM (g Kg -1 ) Stem DW (g m -2 ) Stem FW (g m -2 ) NO 3 - /NH 4 + N level Exp. 0.007 0.332 0.245 Sig. RESULTS 11.70 11.90 11.95 0.198 0.198 0.077 0.166 10.90 11.15 10.80 9.10 0.052 0.021 0.097 11.85 12.15 12.65 18:2 (g per 100g fatty acids) 60.65 60.20 59.80 0.139 0.042 0.042 0.225 62.55 62.65 61.60 60.05 0.999 1.000 0.645 56.55 55.95 56.55 18:3 (g per 100g fatty acids) *Within a column, values with different letters differ significantly (P=0.05) Sig. 0.61 b 0/100 12 0.67 b 40/60 12 0.77 a* 60/40 12 3 rd <0.001 N cubic <0.001 N quadratic 0.002 N linear <0.001 N 0.64 40/60 36 0.70 40/60 24 0.72 40/60 12 0.94 40/60 0 2 nd 0.004 N quadratic <0.001 N linear 0.004 N Sig. 0.70 40/60 16 0.77 40/60 12 0.85 40/60 8 1 st Oxalic acid (mmol g -1 DM) NO 3 - /NH 4 + N level Exp. KEYWORD Nitrogen, ferilization, nutraceuticals, functional food, omega-3-fatty acid, oxalic acid Purslane at harvest Plants grew increasing N level up to 36 mmol L -1 . N supplied in both forms NO 3 - and NH 4 + produced bigger plants compared to N supplied in NH 4 + form only. Significant trends were found for LA and LNA indicating a favourable accumulation of omega-3-fatty acid with increasing N. Keeping high N level in the nutrient solution with 40/60 NO 3 - /NH 4 + ratio would give the best results in terms of yield, oxalic acid concentration and fatty acid profile. POSITIVE COMPOUNDS NEGATIVE COMPOUND REFERENCES Ezekwe, M.O., Omara-Alwala, T.R. and Membrahtu, T. 1999. Nutrient characterization of purslane accessions as influenced by planting date. Plant Foods Hum Nutr 54:139-144. Palaniswamy, U., McAvoy, R.J. and Bible, B. 2000. Omega-3-fatty acid concentration in Portulaca oleracea L. is altered by nitrogen source in hydroponic solution. J Am Soc Hortic Sci 125:190–194. Palaniswamy, U., McAvoy, R.J. and Bible, B. 2001. Stage of harvest and polyunsaturated essential fatty acid concentrations in purslane (Portulaca oleracea) leaves. J Agric Food Chem 49:3490–3493. Simopoulos, A.P., Norman, H.A., Gillapsy, J.E. and Duke, J.A. 1992. Common purslane: a source of omega-3-fatty acids and antioxidants. J Amer Coll Nutr 11:374-382.