Avaliação cariotípica, fenológica, anatômica e nutricional de morfotipos de almeirão-de-árvore (Lactuca aff. canadensis L. - Asteraceae)

Abstract

Lactuca aff. canadensis is an unconventional vegetable from the Asteraceae family. The species was introduced in Brazil, where it is popularly known as almeirão-de-árvore. The almeirão-de-árvore exhibits great morphological variability, especially related to the leaves and there are no records on its agronomic, anatomical and cytogenetic characters, neither for taxonomic identification purposes. It presents divergences in its scientific name, being identified as Cichorium intybus L., Lactuca canadensis L. and Lactuca indica L.. In this work it was referred to as Lactuca aff. canadensis L (aff = in order to). Thus, in order to expand scientific knowledge, of essential characteristics for use in food and cultivation, the aim of the work was to elaborate the cytogenetic, anatomical and nutritional characterization, as well as to evaluate the phenological cycle of different almeirão-de-árvore morphotypes. The morphotypes of almeirão-de-árvore (green, smooth purple with narrow leaf, peaked purple and smooth purple with broad leaf) were obtained from the germplasm collection of the Federal University of Lavras. In the first study, the phenological stages were characterized and the behavior of the productive parameters was evaluated, followed by nutritional characterization, phytochemical composition and antioxidant potential. In the second study, cytogenetic analyzes were carried out to differentiate almeirão-de-árvore morphotypes: determination of the chromosomal number and DNA quantification by flow cytometry and observing the anatomical characters with the determination of stoma type, dimensions and stomatal density. Tree morphotypes have similarities in development, especially in vegetative growth. Some differences were detected in terms of plant height and reproductive period. They presented great productive potential, with production superior to other leafy vegetables such as lettuce, of similar development stages. Phenology also makes it possible to adopt the same management and production system. Plants with high nutritional content were shown, with emphasis on the content of phenolic compounds, vitamin C, in addition to other constituents, such as proteins, macro and micronutrients, especially for the content of Ca, Mg, K and Mn. All genotypes evaluated showed 2n = 18 chromosomes, with a predominance of relatively symmetrical submacentric chromosomes. No significant variations were observed for the DNA content of the four morphotypes, on average 5.88 pg, values that differ from those found in the literature for the species suggested for the almeirão-de-árvore. In the anatomical analysis, the leaves of the almeirão-de-árvore morphotypes tree were classified as hypoamphistomatic. In general, they showed similarities between lobed morphotypes (green and purple) and between smooth purple types (narrow leaf and wide leaf) for the number and size of stomata. The results obtained will contribute to the taxonomy, in the genetic improvement program, recommendations for uses in food, in technology for commercial and seed production, in addition to generating information for scientific knowledge.