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Yacon [Smallanthus sonchifolia (Poepp. et Endl.) H. Robinson], a native plant of the Andes, belongs to the family Compositae (Asteraceae) and it represents a traditional crop of the original population of Peru used in traditional medicine. A major portion of tuberous root biomass is composed of water (> 70% of fresh weight). Saccharides, especially oligofructans, form 70-80% of dry weight, protein content ranges between 0.3% and 3.7%. Fructooligosaccharides of inulin type β (2→1), mainly oligomers (GF 2 -GF 16 ), are known for their ability to keep the colon healthy. Yacon sweetness is predominantly caused by fructose, which is by some 70% sweeter than sucrose. Other oligosaccharides are 1-kestose and nystose. Diabetics and persons suffering from digestive problems are recommended to consume yacon because its sugars are not available from the small intestine. The mean tuberous root composition per 100 g of fresh matter is 81.3, 13.8, 0.9, 1.0, 0.1 and 1.1 g of water, saccharides, fibre, proteins, lipids and ash, respectively. Mean mineral contents per 100 g of fresh matter are 334, 34, 12, 8.4, 0.4 and 0.2 mg of potassium, phosphorus, calcium, magnesium, sodium and iron, respectively. Vitamins B 1 , B 2 , C, β-carotene and polyphenols in the same weight are present at mean concentrations 0.07, 0.31, 5.0, 0.13 and 203 mg, respectively. Yacon can be considered an industrial crop, particularly as a source of inulin. The used forms are flour, syrup, extract from tuberous roots and moreover leaf extract for the preparation of yacon infusion with hypoglycaemic effect. In yacon leaves di-and sesquiterpenes with protective effects against insects are present, among them mainly ent-kaurenic acid (ent-kaur-16-en-19-oic acid) and its derivative -15-α-angeloyloxy-entkauren-19-oic acid 16-epoxide. Other components are polyphenolic antioxidants, esp. hydroxycinnamic acids and chlorogenic acid. A new antifungal melampolide -sesquiterpene lactone named sonchifolin, as well as three known melampolides, polymatin B, uvedalin and enhydrin, were isolated from leaf extracts of yacon. Three major phytoalexins were isolated: 4'-hydroxy-3'-(3-methylbutanoyl)acetophenone, 4'-hydroxy-3'-(3-methyl-2-butenyl)acetophenone and 5-acetyl-2-(1-hydroxy-1-methylethyl)benzofuran.

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This study monitors the effect of salt stress induced by a NaCl solution (0 – deionized water, 50, 100, 200, 300 mmol/L) in lettuce (Lactuca sativa L. cv. Orion), New Zealand spinach (Tetragonia tetragonoides (Pall) Kuntze) and common purslane (Portulaca oleracea L. cv. Green Purslane) over the course of 50 days. The diverse reactions of these monitored species to salt stress are well apparent from the results. Lettuce proved as the most sensitive to salt stress, showing a significant reduction of dry weight, where even lower concentrations of salt affected membrane stability through increased electrolyte leakage value and an imbalance in the content of Na⁺ and K⁺, observed in the form of lower ratios of K⁺/Na⁺. In case of T. tetragonoides, lower salt concentrations positively affected growth and this species appears to particularly accumulate sodium. In case of P. oleracea no significant reduction of dry weight took place with the increasing concentration of NaCl and a naturally high content of potassium contributed to maintaining a favourable ratio of K⁺/Na⁺ even at higher salt concentrations, which is one of the prerequisites of salt-stress tolerance.

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