In vitro cultivation of purple basil Ocimum basilicum L. ‘red rubin’ at different levels of salts, charcoal, sucrose and potassium iodine

Abstract

Ocimum basilicum'red rubin' is highly valued for its essential oil, and is widely used in folk medicine, but few studies examining in vitro propagation techniques for this basil variety are available. We examined the development of red rubin basil seedlings grown in vitro in different concentrations of mineral salts, charcoal combined with sucrose, and potassium iodine in three series of tests. In the first series, five concentrations (0, 25, 50, 75 and 100%) of Murashige and Skoog salts (MS culture medium) were used to germinate sterilized seeds of O. basilicum. In the second test, to evaluate the combined effects of charcoal and sucrose on basil growth, three concentrations of charcoal (0, 3.0, and 4.5 g/L) and two of sucrose (30 and 60 g/L) were used. In the third test, the seeds were sown onto culture medium enriched with five different concentrations of potassium iodine (0, 25, 50, 75 and 100 M); 0.5 M benzyl aminopurine (BAP) and 1.0 M naphthalene acetic acid (NAA) were added to all germination media. A completely randomized experimental design was used in all tests, with five replicates, four vials per test, and 4 seeds per vial. In Test 2, seedling oxidation (%) and the numbers of leaves and shoots were submitted to non-parametric analysis using the Kruskal Wallis test (p =0.05). The other data were submitted to analysis of variance (p=0.05). The qualitative means were evaluated by the Tukey test (p=0.05), and the quantitative means by polynomial regression (p=0.05). The results showed that 100% MS culture medium was most indicated for 'red rubin' seed germination and aerial portion production, while 70-80% MS was indicated for root production. A sucrose level of 30 g/L (standard) combined with 4.5 g/L of activated charcoal allowed the best seedlings development and inhibited callus formation. Activated charcoal limited copper and zinc uptake by O. basilicum seedlings, but not enough to hamper their development. Increasing concentrations of potassium iodine reduced all of the growth variables analyzed in this basil variety.