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.

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.

P arte da tese do prime iro autor para obtenção d o grau d e "Do cto r Scien tiae" n a Un iversidade Federal de Viçosa. ** Pes qu is ad or da EM BR AP A, CN P -Al go dã o -58.100 -Campina Grande -PB. *** Pro fe sso re s da Un iv er si dad e Fe dera l de Viçosa, 36.570 -Viçosa, HG. RESUMOObj eti van do -se a ver ifi cação da res ist ênc ia de genótipos de algod ão ao her bicid a diuron, foi con duzid o um ens aio de cas a- O ensai o foi del ineado em blocos ao acaso , com par celas sub divid idas e com quatr o repetições. As par celas foram as doses do her bicid a 0,000; 0,048; 0,096; 0,357; 0,714 e 1,428 kg/ ha, apl icad as quand o as plant as estavam no est ádi o de uma a duas fol has ver dad eiras, na super fíc ie do sub str ato , que foi de are ia de rio lavad a, evi tan do-se o con tacto com a fit omassa hidratada epí gea das plant as. As sub par cel as for am os ge nótip os de algod oei ro.Cad a par cela era represent ada por uma cai xa de mad eir a de 37,2cm x 40,7cm x 11,0cm de dimen sõe s, preen chi da com areia de rio , onde foram col ocada s as semen tes, por lin ha, de cada gen ótipo, previ amente trata das com ácido sulfúrico.Os resul tad os mos traram que os cul tivar es IAC-17 e BR -1 foram mai s resis tentes ao estres se quími co cau sado pel o herb icida, que os demais gen ótipos testado s, con for me foi revel ado pel os val ores obtid os para as var iávei s: grau de fit otoxici dade, 15 dias apó s a apl icaçã o do produto, alt ura plant ular, peso da fitomassa hidrata da, peso da fitomassa, taxa de elongaç ão caulinar e taxa de crescimen to relat ivo em fit o-mas sa hidratada epí gea.O cul tivar Rim-de -Boi mostr ou-se o mais sen sível ao diuron ten do -se ver ifi cad o que, com uma dose de 0,096 kg/ ha, o estresse já se transfor mav a em dan o. O cul tivar C-71, que é um polih íbric o nat ural, envol ven do os gen oma s do G. hir sut um lat ifoliu m e do G. bar bad ense, aprese nt ou -se in te rm ed iá ri a, no qu e se re fe re à ca pacidad e de resi sti r ao est ress e quími co pro vo cado pelo diuron.Ta is re su lt ad os ev id en ci am que na re co me n - SUMMARY R E S I S T A N C E O F C O T T O N S P E C I E S A N D CULTIVARS TO THE HERBICIDE DIURONTo d etermin e th e resistan ce o f cotton sp ec i e s a n d cu lt i va r s to t h e h e rb i c id e d iu ro n, a green house test wa s conducted in Viçosa, Mina s Gera is . Geno ty pe s of th e sp ecie s Go ss yp iu m: h i r s u t u m l a t i f o l i u m H u t c h . ( c v I A C 1 7 a n d BR 1 ), G. hirsu tu m ma rie g a lan te Hutch . (cv Veludo C 17), and G. ba rbad ense bra silien se Hu tch . (cv rim -d e-bo i) were stu d ied . A sp lit pl ot in a ra nd omi ze d co mp le te bl ock des ig n wa s u t i l i z e d i n t h i s e xp e r i m e n t . T h e m a i n p l o t s we re the herb ic id e dosage (0,0 0, 0,0 48, 0,0 96, 0, 35 7, 0, 71 4 an d 1, 42 8 kg a. i. /h a) ap pl ie d to th e san d su b strat wh en th e p lan ts h ad on e or two true leaves, and the subplot were the genotypes.Each p lo t was rep resen ted b y a wo o d bo s (3 7 x 47 ...

This chapter focuses on the virulence mechanisms of predaceous, endoparasitic, toxin-producing and egg and female-parasitic fungi. The importance of identifying and considering the specificity of these fungal biological control agents against the developmental stages of certain plant parasitic nematode species in the management of these nematodes is also discussed.

Twenty cassava cultivars (Manihot esculenta Crantz) were analyzed for fatty acids, nonstructural carbohydrates and crude protein contents. The main constituent fatty acids were myristic, palmitic, stearic, oleic, linoleic and linolenic. Trace amounts of lauric, myristoleic and palmitoleic acids were detected. Saturated acids ranged from 26.58 to 58.05%. Acid‐digestible carbohydrates ranged from 11.82 to 40.70% of the green matter. Reducing and non‐reducing soluble oligosaccharides also were determined. Crude protein ranged from 1.39 to 4.70% of the dry matter. Linear regression analyses were made, but no significant correlations were found. Some possible genetic relationships are proposed for certain cultivars.

On minitomatoes, the soluble solids content (SSC) is a fundamental characteristic for commercialization. Therefore, is essential to evaluate the genetic diversity among the genotypes, looking their SSC and also the SSC variation, related to the position of the cluster, mainly due to the new technologies – tomato hybrids obtained from dwarf lines. In this sense, the objective of the experiment was to evaluate the genetic variability and the influence of the cluster’s position on the SSC, in minitomato genotypes that were obtained from dwarf lines. The experiment were conducted on a greenhouse and set up in a completely randomized design, with subdivided portion of 13 hybrids x 5 cluster’s position and four replications. The SSC of the fruits were evaluated according with their position of the clusters, being the values expressed in 0Brix. The genetic diversity was obtained by multivariate analyzes, using the generalized distance of Mahalanobis, utilizing different grouping methods (UPGMA and Tocher). The hybrids performance for SSC was checked by the Scott-Knott test (p=0.005). The cluster’s position influenced on the SSC of the minitomatoes fruits and the first cluster of all hybrids that were evaluated, presented the highest SSC. Besides that, the highest 0Brix variability among the genotypes occurred when the fruits were harvested on the fifth and first cluster. Most hybrids originated from dwarf lines did not presented a reduce on 0Brix values during the harvests.

The characterization of germplasm banks is essential for successful breeding programs. There is no consensus on which multivariate analysis method is the most appropriate to characterize a round tomato germplasm bank. This study aimed to characterize the genetic divergence between tomato accessions to assess whether there is agreement between the hierarchical and optimization methods and to recommend promising combinations for obtaining hybrids. The experiment was conducted at the Experimental Vegetable Station of the Federal University of Uberlândia in 2016. The experimental design was a randomized block design with 32 treatments, including 31 tomato genotypes and a commercial control (cv. Rio Grande), with four replicates. The results showed genetic variability between genotypes. The UPGMA hierarchical method allowed greater discrimination between genotypes. Crossing the genotypes UFU-85#9 salada-D, UFU-91#5 salada-D, and cv. Rio Grande will lead to hybrids with high chlorophyll content, high yield, high fruit mass, and fruits with high soluble solids.