Salt-induced changes in solutes, pigments and essential oil of two basil (Ocimum basilicum L.) genotypes under hydroponic cultivation

Abstract

The aim of this study was to evaluate the effect of salt stress on the contents of inorganic and organic solutes, pigments and essential oil in two basil genotypes cultivated in hydroponic system. The experiment was carried out in a greenhouse. Treatments were distributed in randomized blocks, in a 2 × 2 factorial arrangement, corresponding to two contrasting genotypes (‘Toscano folha de alface’ (TFA) and ‘Gennaro de menta’ (GM)) and two salt levels (0 - control and 80 mM NaCl), with six replicates. The Na+, Cl- and K+ accumulation in the leaves, stem and roots did not differ between genotypes. Salt stress increased free amino acids accumulation in the leaves of the TFA genotype. The proline content increased in the roots of both genotypes. However, in GM genotype, the proline content (3.12 mmol g-1 dry mass (DM)) was around 2-fold greater when compared to TFA genotype (1.48 mmol g-1 DM). The salt stress increased the photosynthetic pigments content only in the GM genotype. Inorganic solutes and photosynthetic pigments content are not good indicators of salt-tolerance in the studied genotypes. Under salt stress, there was increase in oil content in GM genotype, while the TFA genotype showed a decrease compared to control treatment. In spite of showing lower oil content, the TFA genotype showed higher yield and productivity of essential oil compared to GM under salt stress conditions.