Efeito da aplicação do ácido salicílico em genótipos de manjericão (Ocimum basilicum L.) sob aspectos químicos e fisiológicos

Abstract

Basil (Ocimum basilicum) is a perennial plant and belongs to the Lamiaceae family. Their genotypes can be classified according to their aroma or also by morphological characteristics. Its essential oil is of great importance in the perfumery industry and also in the aromatization of food and beverages, and still presents medicinal, insecticidal and repellent properties. A substance that stimulates the defenses of plants is salicylic acid (SA) which induces mechanisms of responses. The use of SA when applied directly to plants may have the same effect. The participation of SA in the expression of systemic resistance is because of its ability to induce the synthesis of PR-Proteins. This study aimed to analyze the chemical effects as the determination of volatile and physiological charactheristics as aerial and root dry mass, gas exchange and photosynthetic pigments, under the administration of salicylic acid in three different genotypes of basil: Alfavaca Basilicão, Gennaro de Menta and Limoncino. Only the cultivar Gennaro showed sensitivity to the application of AS in relation to DMAP, with a gain of 15.4%. There was an increase of RDM in all analyzed genotypes. As for leaf area, all the varieties were responsive, Basilicão obtained a greater gain of 35%. The genotypes of Basilicão and Gennaro showed a reduction in their photosynthetic rates when treated with AS, while Limoncino showed a slight growth. The administration of AS promoted reduction of chlorophyll A contents of 11.5% and 4.5% for Alfavaca Basilicão and Gennaro, and an increase of 8.5% for Limoncino. Increase in chlorophyll B and total, were observed only in Gennaro. Carotenoids increased to Limoncino gain of 11.1%, and reduced to the other varieties. The major compounds in the Alfavaca Basilicão cultivars were Eucaliptol and Linalol, in the Gennaro de Menta cultivar were Estragol and Eucalyptol and in the Limoncino cultivar the major compounds were citral and estragol in the control, while the AS application favored the appearance of Geranial and Lemonal (isomers of citral). The different responses obtained here reflect the complexity of working with aromatic plants and reinforce the importance of studying cultivars especially Ocimum basilicum.