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An experiment was carried out to evaluate the behaviour on salt stress induced by sodium chloride of two melon clones obtained from micropropagation. Since arbuscular mycorrhizal (AM) fungi seem to increase salt tolerance in some crops, at acclimatisation melon plantlets were mycorrhizal with an AM fungus. The root systems of both mycorrhizal and non mycorrhizal plants were exposed to increasing salt concentrations and then placed in distilled water to study the wilting response and the recovery of plants. Observations were made on several morphological parameters, in particular to verify the modification of root system morphology caused by AM fungus, as demonstrated already by several studies. The analysis of infected roots was carried out following Phillips and Hayman's protocol (1970). Afterwards, the specimen was read using an optical microscope.

Helichrysum italicum (Roth) G. Don is an aromatic plant of the Asteraceae family that grows spontaneously in Mediterranean areas. Among the very large number of phytoproducts that can be obtained from this species, essential oils are successfully used both in cosmetics and in pharmaceutical preparations for their antiinflammatory and antimicrobial activities. The main constrain for industrial sector is that spontaneous plants are extremely variable. The presence of an innovative technique that provides selected and uniform plants could be a good strategy for the success of this interesting species. Leaf fragments of H. italicum micropropagated plants were used as explant source. The explants were cultured in a medium containing MS macronutrients (Murashige and Skoog, 1962) and micronutrients from Nitsch and Nitsch (1972), Fe-EDTA (30 mg L -1 ), thiamine HCl (0.4 mg L -1 ), myoinositol (100 mg L -1 ), sucrose ( 30 g L -1 ) and agar (7 g L -1 ). For organogenesis induction, basal medium supplemented with thidiazuron (TDZ 0.1, 0.5, 1, and 2 mg L -1 ) alone or in combination with naphthalene acetic acid (NAA 1 mg L -1 ) were used. The results showed that H. italicum has a great organogenic capacity: the explants formed adventitious shoots for each treatment through the callus formation or directly from the leaves on the hormone-free medium. Rooting frequency was near 100% on leaves cultured in the hormone-free medium. In conclusion, leaf explants give encouraging results in organogenesis allowing to exploit this technique in commercial production of H. italicum extracts.