Understanding genetics and the gene interactions involved in the expression of certain characteristics becomes a determining factor for better exploration of its use. The development of breeding programs that combine one or more desirable trait into a single cultivar is directly impacted by this lack of knowledge of the genetic bases involved. The objective of the present study was to estimate the genetic parameters involved in pigment expression and agronomic characteristics in lettuce. Parental evaluations of lettuce, P1 (green) and P2 (purple) parental generations, the segregating generations F1 and F2, and the backcrosses Bc1 and Bc2 originating from the UFU-Crespa199#1#1 x UFU-Albina#2 crossing were evaluated. The chlorophyll and anthocyanin contents, number of leaves and plant diameter were evaluated. The study was conducted by testing all generations and the estimates obtained by averages and variances. Indications of polygenic or oligogenic inheritance were verified by the characteristic number of leaves, plant diameter, and anthocyanin content. The complete and additive-dominant models satisfactorily explained the performance of the variables, except the anthocyanin content.

Lettuce is the most-consumed leafy vegetable in Brazil due to its ease of preparation, nutritional quality, and affordability. Despite these benefits, there are few cultivars of crisphead lettuce (Lactuca sativa) that possess agronomic potential, high carotenoid content and resistance to nematodes. Therefore, we evaluated the agronomic potential of crisphead lettuce genotypes that are resistant to the root-knot nematode. The experiment was conducted at the Vegetable Experiment Station of the Federal University of Uberlandia (UFU), Monte Carmelo Campus. The trial was set up in a randomized block design with 49 treatments (43 genotypes obtained from crosses between Uberlandia 10000 and Belissima and six commercial cultivars) and three replications. After preparing the beds and before transplanting the seedlings, 11 simple samples were taken from each of the three experimental blocks to confirm the presence of nematodes within the experimental area. The following variables were determined 48 days after transplanting: chlorophyll content, leaf temperature, plant diameter, number of leaves per plant, fresh mass and incidence of root gall. The data were submitted to analysis of variance (ANOVA) and an F-test and the means were compared by the Scott-Knott test. Genetic diversity was represented by a dendrogram that was obtained using the hierarchical method of UPGMA and the optimization method of Tocher. We found genetic divergence and agronomic potential among the evaluated genotypes. Specifically, 199#1#1-E, 199#2#1-E, 199#2#2-E, 199#3#1-E, 199#6#1-E and 75#2#2-E presented good agronomic potential, were rich in carotenoids and showed resistance to the root-knot nematode.

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Vegetables with high carotenoids content can help to prevent many diseases. Lettuce is one of the most consumed vegetables all over the world that present potential for biofortification investment. However, there are few genotypes of lettuce biofortificated on the market and for direct use in plant breeding. Evaluate new lettuce genotypes that are rich in carotenoids are essential in order to know the commercial potential and their usefulness as possible parents in breeding programs. Therefore, the experiment aimed to evaluate the agronomic potential and genetic dissimilarity between lettuce genotypes with different levels of carotenoids. It was conducted in a randomized block design, with 83 treatments and two replications. During the course of the trial, were evaluated quantitative characters: leaf chlorophyll content (a, b and total), canopy diameter and number of leaves; and qualitative characters: size, color and shape of the leaves. The genetic diversity was obtained by multivariate analyzes using the sum of quantitative and qualitative data and, after that, using different grouping methods (UPGMA and Tocher). The genotypes showed genetic dissimilarity and agronomic potential for different lettuce segments and high carotenoids content. Among the evaluated characters, total chlorophyll content represented the main contribution for genetic variability. There was no coherence between the hierarchical method of UPGMA and the optimization method of Tocher when used for determinate the genetic diversity between lettuce genotypes with different levels of carotenoids.

The growing of Piper aduncum for essential oil extraction has increased, but there is a lack of basic information about its management and cultivation, which allows the productivity and quality of the oil, in order to attend the market demands. This study aimed to evaluate the relation between the production of essential oils from P. aduncum and soil water pressure heads (20 kPa, 40 kPa, 60 kPa, 100 kPa and non-irrigated). The assessment comprised the quantification of idioblasts and the production of essential oil extracted from leaves of cultivated plants. The variation in the soil water pressure head alters the amount of idioblasts in P. aduncum leaves, with impacts on the essential oil production. A soil water pressure head range of 20-60 kPa is sufficient for this species to express the highest amount of idioblasts and the highest level of essential oil production. The species adapts itself to different water availability conditions in the soil. Under stress conditions, due to water deficit or excess, the production of essential oil is reduced.