Caracterização de dois acessos de Ocimum.

Abstract

Lamiaceae (= Labiatae) is a botanical family with several species with medicinal properties, including the genus Ocimum consisting of 50 to 150 species of herbs and subshrubs widely distributed in tropical and subtropical regions of Asia, Africa, Central America and South. O. gratissimum L. (alfavaca-cravo) is used as febrifuge, diuretic, and several studies in the literature show that the bioactivity of the essential oil of the species as antibacterial, antifungal and antiparasitic. Alfavaca-roxa is able to reverse its color purple to green, depending on the condition of shading. The objective of this work was to evaluate the morphological, agronomic, chemical and cytogenetic characteristics of alfavaca-cravo and alfavaca-roxa. A study was conducted to evaluate the effect of temperature, light and KNO3 on seed of species. Experiment was carried out using a completely randomized design in a 2x2x5 factorial arrangement: two different light expositions; KNO3 (0%; 0,2%) and five temperatures (20ºC; 25ºC; 30ºC; 35ºC; 20-35ºC). Growing the crop was carried out in two environments: 50% shading in a greenhouse; in the sun with no shade. Aiming to analyze the growth of plants grown at two different environmental conditions, an experiment was conducted with a duration of 90 days, using a completely randomized design with four replications and two plants per replication. The variables analyzed were: stem diameter, height, number of leaves, leaf area, root length, dry weight and oil content. To evaluate the essential oil yield of medicinal plants in different environmental conditions, an experiment was performed with duration of 90 days, using a randomized design with four replications and two plants per replicate. The preliminary chemical composition of the essential oils was determined by Nuclear Magnetic Ressonance 1H analyses. In a proposed protocol for extraction of DNA polymorphisms were used to detect 19 primers by RAPD. In cytogenetics was determined the number of chromosomes of the specimens studied from young roots pretreated with 2 mM 8-hydroxyquinoline, were stained with Giemsa 2%. The viability of pollen grains was checked by the method of staining with acetic carmine. Alfavaca-cravo is positive photoblastic and alfavaca-roxa, photoblastic preferential. Germination did not exceed 24% in all treatments. Temperature of 30ºC was the best condition for seed germination for alfavaca-cravo and 20-35ºC for alfavaca-roxa with KNO3, darkness. Germination is epigeous. For both species, higher yields were obtained in samples from the environmental conditions in the sun. The essential oil the species presented β-caryophyllene, 1,8 – cineole, eugenol. The number of mitotic chromosomes found for the samples was 2n = 40, which is in agreement with the number recorded previously in the literature. The species showed a high percentage of pollen viability.