ABSTRACT Lettuce seeds usually show germination problems that can be related to dormancy and or thermoinhibition, as well as to the genotype constitution. The knowledge of the temperature at which the thermoinhibition process begins, as well as the influence of the age of the seed on its germination, is extremely important to establish more suitable parameters for the selection of higher genotypes in breeding programs. The objective of this work was to evaluate the seed germination of three lettuce cultivars according to the enviromental temperature and the age of the seeds. The cultivars Everglades (tolerant to thermoinhibition), Luisa (medium tolerant) and Verônica (sensitive) were used. Seeds of each cultivar were evaluated by the standard germination test, first count test, germination speed index and germination test of remaining seeds. The analyses were performed at four environmental temperatures and in seven storage periods after harvest. None of the cultivars showed primary dormancy. The tolerance to thermoinhibition showed by cultivars Everglades and Luisa and the sensitivity of cultivar Verônica were confirmed. The most suitable temperature for differentiating tolerant and sensitive thermoinhibition genotypes occurred from 30.5 ºC and 260 days after harvest.

ABSTRACT. Removal of lettuce basal leaves is a technique used by the seed industry; however, the effects on seed production and physiological potential are unknown. Genetic dissimilarity is fundamental in the identification of individuals in terms of traits of interest, although it is rarely considered in relation to seeds that are tolerant to thermoinhibition. The aim of this study was to ascertain the relationship between defoliation of lettuce plants and seed yield/physiological quality, as well as the genetic dissimilarity among genotypes with regard to seed thermoinhibition. We used 35 lines of biofortified lettuce, the cultivars Uberlândia 10000, Belíssima, UFU MC BIOFORT1, and Everglades (tolerant to thermoinhibition), and Grand Rapids and Verônica (susceptible to thermoinhibition). The seed yield and physiological quality of the genotypes with and without defoliation were evaluated, artificially aged, and germinated at four temperatures in a factorial arrangement. The genetic dissimilarity was estimated by Tocher graphing and the UPGMA clustering method, based on the Mahalanobis generalized distance (D2 ii). Four UFU genotypes and Grand Rapids had high seed yields. With removal of basal leaves, there was higher seed yield per plant and there was an effect on their physiological quality. The genotypes exhibited genetic variability for thermoinhibition, with UFU-86#2#1#1 and Everglades showing similar performance.

Abstract: The thermoinhibition of lettuce seed germination causes important losses for producers, who do not have thermotolerant commercial cultivars. One of the obstacles has been the scarcity of optimizing techniques capable of efficiently discriminating thermotolerant and thermosensitive cultivars. The aim of this work was to evaluate the use of neural networks to discriminate different levels of thermoinhibition in lettuce seeds. Seeds of 18 cultivars were evaluated for thermoinhibition considering the characteristics of the first and last germination count and germination speed index, in seeds subjected to temperatures of 20, 25, 30 and 35 °C. The remaining seeds, which did not germinate, were subjected to the tetrazolium test. Analyses were performed immediately after seed harvesting and repeated after six months of storage. Discriminant analysis was performed and the Kohonen’s Self-Organizing Map (SOM) was created using Artificial Neural Networks (ANNs). Neural networks discriminate lettuce cultivars and organizes them in terms of seed thermoinhibition tolerance through Kohonen’s Self-Organizing Map. Discriminant analysis consistently identifies the Everglades and Luiza genotypes as tolerant to thermoinhibition.

Resumo: A termoinibição causa perdas importantes para os produtores, os quais não dispõem de cultivares comerciais com sementes termotolerantes. Há escassez de técnicas otimizadoras capazes de discriminar cultivares termotolerantes e termosensíveis com eficiência. Objetivou-se avaliar o uso de redes neurais para discriminar diferentes níveis de termoinibição em sementes de alface. Foram avaliadas sementes de 18 cultivares quanto à termoinibição considerando às características de primeira e última contagem de germinação e índice de velocidade de germinação, em sementes submetidas às temperaturas de 20, 25, 30 e 35 °C. As sementes remanescentes, que não germinaram, foram submetidas ao teste de tetrazólio. As análises foram realizadas imediatamente após a colheita das sementes e repetidas após seis meses de armazenamento. Uma análise discriminante e o Mapa Auto-Organizável de Kohonen (SOM) por Redes Neurais Artificiais (RNA’s) foram realizados. As redes neurais discriminam as cultivares de alface e as organiza quanto a tolerância a termoinibição das sementes por meio do Mapa Auto-Organizável de Kohonen. A análise discriminante indentifica de maneira coerente o genótipo Everglades e Luiza como tolerantes a termoinibição.

RESUMO As altas temperaturas interferem no cultivo da alface. A termoinibição da germinação das sementes e florecimento precoce causam perdas importantes para os produtores. Os objetivos deste trabalho foram avaliar a tolerância ao florescimento precoce, verificar a dissimilaridade genética e selecionar cultivares de alface tolerantes à termoinibição de sementes. Foram avaliadas 18 cultivares. Para florecimento precoce verificou-se o número de dias para a primeira antese. Em relação à termoinibição de sementes avaliou-se a primeira e última contagem de germinação e o índice de velocidade de germinação, utilizando-se as temperaturas de 20, 25, 30 e 35ºC. As análises foram realizadas imediatamente após a colheita e após seis meses de armazenamento. O estudo da dissimilaridade genética foi realizado por meio do método de otimização de Tocher Gráfico e hierárquico UPGMA. Os modelos de regressão foram ajustados e o agrupamento das curvas foi realizado testando a identidade dos modelos. Florescimento precoce foi observado nas cultivares Floresta, Colorado, Grand Rapids e Everglades. As cultivares apresentaram variabilidade genética e são diferentes quanto à tolerância à termoinibição. Ao agrupar as equações de regressão foi possível selecionar cultivares tolerantes à termoinibição.

ABSTRACT High temperatures interfere with lettuce cropping. Thermoinhibition of seed germination and early flowering cause important losses for farmers. The objectives of this work were to evaluate the tolerance to early flowering, to verify the genetic dissimilarity and to select lettuce cultivars tolerant to seed thermoinhibition. 18 cultivars were evaluated. The number of days until the first anthesis was verified for early flowering. Regarding seed thermoinhibition, the first and final germination counting and germination speed index were evaluated, using temperatures of 20, 25, 30 and 35ºC. The analyses were performed immediately after harvest and after six months under storage. The genetic dissimilarity was obtained using the Tocher Graph optimization and hierarchical UPGMA methods. Regression models were adjusted, and curves’ clustering was performed by testing the identity of the models. Early flowering was observed in cultivars Floresta, Colorado, Grand Rapids, and Everglades. Cultivars showed genetic variability and are dissimilar regarding tolerance to thermoinhibition. By clustering the regression equations, it was possible to select thermoinhibition tolerant cultivars.

Resumo O objetivo deste trabalho foi determinar o controle genético da tolerância à termoinibição em sementes de alface (Lactuca sativa). Utilizaram-se sementes das gerações F1, F2 e F2:3 oriundas do cruzamento entre as cultivares Everglades (tolerante à termoinibição) e Verônica (sensível à termoinibição), além de sementes dos próprios genitores. Realizaram-se testes de germinação das sementes em delineamento completamente casualizado, com quatro repetições para cada um dos genitores, oito para a F1 e quatro para cada uma das 26 progênies F2:3. A média da população F2 foi considerada como a média da amostra das 26 progênies. O controle genético da tolerância à termoinibição em sementes de alface é atribuído a um ou poucos genes. Os efeitos aditivos são mais expressivos do que os não aditivos, e a herdabilidade no sentido restrito é relativamente alta, o que permite antever sucesso com a seleção.

Abstract The objective of this work was to assess the genetic control of tolerance to thermoinhibition in lettuce (Lactuca sativa) seeds. Seeds of the F1, F2, and F2:3 generations derived from the cross between cultivars Everglades (tolerant to thermoinhibition) and Verônica (sensitive to thermoinhibition) were used, besides seeds from the parents. Seed germination tests were conducted in a completely randomized design, with four replicates of each parent, eight of F1, and four of each of the 26 F2:3 progenies. The mean of the F2 population was considered as the mean of the sample of the 26 progenies. The genetic control of thermoinhibition tolerance in lettuce seeds is attributed to one or a few genes. The additive effects are more expressive than the nonadditive ones, and narrow-sense heritability is relatively high, allowing the prediction of success in selection.

RESUMO Dormência em sementes de alface é um processo que ainda não está totalmente compreendido. As altas temperaturas de armazenamento podem causar dormência das sementes e promover mudanças fisiológicas e enzimáticas. O objetivo deste trabalho foi verificar a influência dos períodos e dos ambientes de armazenamento na qualidade e dormência de sementes de diferentes cultivares de alface e investigar as alterações bioquímicas. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 4x8x3 para avaliar a qualidade fisiológica de oito cultivares de alface (Everglades, Babá de Verão, Elisa, Luiza, Grand Rapids, Hortência, Salinas 88 e Rubete) em diferentes períodos (30, 60, 90 e 120 dias) e ambientes de armazenamento (15, 25 e 35°C). A atividade bioquímica foi avaliada pelo teste de tetrazólio e pela a atividade da endo-β-mananase. Há alterações fisiológicas e bioquímicas nas sementes de alface em virtude do período e do ambiente de armazenamento em altas temperaturas. Há uma redução da qualidade das sementes a temperaturas elevadas de armazenamento, principalmente aos 120 dias. Verificou-se que o período de armazenamento até os seis meses mantém a viabilidade e vigor de sementes de alface, quando armazenadas a 15°C. As sementes armazenadas em ambientes com temperatura superior a 25°C não toleram o armazenamento a partir de 60 dias o que compromete a germinação e o vigor. A cultivar Everglades é tolerante à condição de germinação a 35°C e mantém sua qualidade ao longo do armazenamento em temperatura de 15°C. A temperatura acima de 25°C induz à termodormência das sementes nas cultivares de alface durante o armazenamento. O teste de tetrazólio indica que as sementes estavam viáveis, contudo não houve germinação em temperaturas elevadas. Ocorrem alterações enzimáticas nas sementes armazenadas em temperatura de 35°C devido à dormência. Houve decréscimo na expressão da enzima endo-β-mananase, sendo influenciada pelo ambiente e período de armazenamento. A cultivar Everglades é termotolerante.

ABSTRACT Dormancy in lettuce seeds is a process not yet fully understood. High storage temperatures can cause seed dormancy promoting physiological and enzymatic changes. The goal of this study was to investigate the influence of storage period and environments on the quality and dormancy of different lettuce cultivars. We also investigated the biochemical changes. A completely randomized experimental design was used in a 4x8x3 factorial arrangement to evaluate physiological quality on different storage periods (30, 60, 90 and 120 days) and environments (15, 25 and 35°C) of seeds from eight lettuce cultivars (Everglades, Babá de Verão, Elisa, Luiza, Grand Rapids, Hortência, Salinas 88 and Rubete). The biochemical activity was accessed by tetrazolium test and the activity of the endo-β-mannanase. There occurred physiological and biochemical changes on lettuce seeds under periods and high temperature storage environments. A reduction of seed quality occurred at high storage temperatures mainly when stored during 120 days. The storage period up to six months maintains the viability and vigor of lettuce seeds, when stored at 15°C. Germination is compromised when seeds are stored over 60 days on temperatures over 25°C. Everglades is a tolerant cultivar to germination conditions of 35°C and maintains its quality during storage at 15°C. Temperatures over 25°C induce thermodormancy on lettuce seeds during storage. The tetrazolium test indicates that the seeds were viable; nevertheless, there was no germination at high temperatures. Enzymatic changes occurred in seeds stored at 35°C due to dormancy. There was a decrease in the expression of endo-β-mannanase enzyme being influenced by the environment and storage period. The Everglades cultivar is thermotolerant.

Resumo: Objetivo deste trabalho foi determinar alterações fisiológicas e isoenzimáticas em sementes de alface em diferentes condições e períodos de armazenamento. Utilizou-se o delineamento experimental inteiramente casualizado com quatro repetições, em arranjo fatorial com seis cultivares de alface (Everglades, Babá de Verão, Elisa, Grand Rapids, Hortência e Salinas 88) e quatro períodos de armazenamento (30, 60, 90 e 120 dias), em três ambientes de armazenamento (15, 25 e 35 oC). A qualidade fisiológica foi avaliada por meio de testes de primeira e contagem final de germinação, emergência, índices de velocidade de germinação e de emergência. As expressões isoenzimáticas determinadas foram as de catalase (CAT), esterase (EST), álcool desidrogenase (ADH) e malato desidrogenase (MDH). As sementes de alface quando armazenadas em ambiente de 15 oC conservaram a qualidade fisiológica. As altas temperaturas do ambiente associada aos maiores períodos de armazenamento causam redução da qualidade fisiológica e alteração dos padrões enzimáticos de CAT, EST, ADH e MDH. No armazenamento a 15 oC não ocorreu alterações nas sementes. As cultivares de alface, especialmente Everglades, apresentam diferentes níveis de tolerância ao armazenamento e expressões isoenzimáticas.

Abstract: The objective of the study was to determine the physiological and isozyme alterations in lettuce seeds submitted to different conditions and storage periods. We used a completely randomized design with four replications in a factorial arrangement with six lettuce cultivars (Everglades, Babá de Verão, Elisa, Grand Rapids, Hortência and Salinas 88) and four storage periods (30, 60, 90 and 120 days), on three storage rooms (15, 25 and 35 ° C). The physiological quality was evaluated by first and final germination count, emergence, and germination and emergence speed indexes. The isoenzyme expression of catalase (CAT), esterase (EST), alcohol dehydrogenase (ADH) and malate dehydrogenase (MDH) were determined. The physiological quality of lettuce seeds was preserved when stored at 15 ° C room temperature. The high room temperatures associated with higher storage periods cause a reduction in physiological quality and alterations in enzymatic patterns of CAT, EST, ADH and MDH. For seeds stored at 15 ° C, there were no physiological changes. The lettuce cultivars, especially Everglades, have different levels of tolerance to storage and isoenzyme expressions.

The objective of this study was to evaluate sweet potato clones for resistance to root-knot nematode, Meloidogyne incognita races 1 and 3. For each nematode physiological race, a greenhouse experiment was set up in a randomized block experimental design with three replications and six plants per plot. Fifty-eight sweet potato clones from the UFVJM germplasm bank were evaluated, plus five commercial cultivars (Brazlândia Rosada, Brazlândia Branca, Palmas, Princesa and Coquinho), plus the cv. Santa Clara tomato (susceptible to Meloidogyne spp.). Stems were planted in 72-cell expanded polystyrene trays, filled with commercial substrate and inoculated with the pathogen thirty days after planting. Forty-five days after inoculation, the eggs were extracted, counted, and later evaluated. Resistance level classification was performed based on reproduction factor (RF) and reproduction index (RI). Among the 63 analyzed clones, a percentage of 78% were classified as resistant to M. incognita race 1.79% to race 3 and 67% showed multiple resistance to both M. incognita races.

The objectives of this work were to assess heterosis and its components in F 1 hybrids of a diallel cross among lines of scarlet eggplants (Solanum gilo Raddi, syn. S. aeth opicum L.), and to study the modes of gene action associated with its expression. Six lines (Morro Redondo, Branco Comprido, BGH-1544, Tinguá, Irajá, Comprido Verde Claro) and 15 hybrids resulting from a diallel cross among them (reciprocals excluded) were tested in a randomized complete block design with four replications. Traits under study were total yield, mean fruit mass and fruit length/diameter ratio. There was no evidence of epistatic gene action in the expression of any of the traits under study. Heterosis for yield could be explained by overdominance, but higher yields were only weakly associated with larger frequencies of dominant alleles an indication that yields may be markedly influenced by the action of relatively few loci with overdominant gene action. Heterosis for mean fruit mass was associated with incompletely dominant gene action, and larger fruit mass was associated with larger proportions of dominant alleles. For fruit length/diameter ration (L.D -1 ), heterosis was due to incompletely dominant gene action, and dominant alleles were predominantly associated with lower L.D-1 values.

Los objetivos de este trabajo fueron evaluar la heterosis y sus componentes en los híbridos F1 de una dialélico entre líneas de jiló (Solanum gilo Raddi, syn. S. aethiopicum L.), y el estudio de los modos de acción de los genes asociados con su expresión. Seis líneas (Morro Redondo, Branco Comprido, BGH-1544, Tinguá, Irajá, Comprido Verde Claro) y 15 híbridos resultantes de un cruce dialélico entre ellos (recíprocos excluídos) se pusieron a prueba en un diseño de bloques completamente aleatorio con cuatro repeticiones. Los rasgos estudiados fueron producción total, peso promedio del fruto y la relación longitud/diámetro. No hubo evidencia de la acción de genes epistatic en la expresión de cualquiera de los rasgos en estudio. Para la producción total, la heterosis se explica por la acción de genes overdominance, ya que había una asociación débil, no significativa, entre los alelos dominantes y los valores de producción de frutas altas totales. La heterosis de masa media de la fruta se asoció con la acción del gen dominante incompleto, y la masa da fruta más grande se asoció con una mayor proporción de alelos dominantes. Para la relación longitud/diámetro (LD -1 ), la heterosis fue debida a la acción del gen dominante incompleto, y alelos dominantes se asociaron principalmente con menores valores LD-1 .

O objetivo deste trabalho foi identificar a aptidão de genótipos de batata-doce (Ipomoea batatas) para consumo humano, produção de etanol e alimentação animal, por meio de índices de aptidão. Os índices de aptidão corresponderam às médias dos valores das variáveis padronizadas para 16 características de interesse, ponderadas por pesos atribuídos a cada característica, conforme a aptidão avaliada. Utilizou-se o delineamento experimental de blocos ao acaso, com duas repetições e 39 genótipos: 36 acessos da coleção de germoplasma da Universidade Federal de Lavras e três cultivares comerciais (Palmas, Brazlândia-Branca e Brazlândia-Rosada). Oito genótipos foram considerados aptos à produção de etanol, 11 à alimentação animal e 11 ao consumo humano, incluindo as cultivares Palmas e Brazlândia-Branca. Os acessos UFLA07-12, UFLA07-31, UFLA07-43, UFLA07-49 e UFLA07-53 apresentaram aptidão para produção de etanol, alimentação animal e consumo humano. O índice de seleção é eficiente para estabelecer aptidões para genótipos de batata-doce.

The objective of this work was to identify agronomic aptitudes of sweet potato (Ipomoea batatas) genotypes for fresh consumption, ethanol production, and animal feed, using aptitude indices. The aptitude indices were established as the weighted means of standardized variables for 16 traits of interest, using different weights for each trait according to the evaluated aptitude. The experimental design was a completely randomized block, with two replicates and 39 sweet potato genotypes: 36 accessions of the germplasm collection of Universidade Federal de Lavras (Brazil) and three commercial cultivars (Palmas, Brazlândia-Branca e Brazlândia-Rosada). Eight genotypes were considered apt to ethanol production, 11 to animal feed, and 11 to human consumption, including the cultivars Palmas and Brazlândia-Branca. The accessions UFLA07-12, UFLA07-31, UFLA07-43, UFLA07-49, and UFLA07-53 showed aptitude for ethanol production, animal feed and human consumption. The selection index is efficient in establishing aptitudes for sweet potato genotypes.

O objetivo deste trabalho foi identificar genótipos de alface, batata-doce, feijão, tomate e Capsicum resistentes ao nematoide Meloidogyne enterolobii (Syn. M. mayaguensis) e classificá-los quanto ao grau de resistência. Foram avaliados: 10 genótipos de alface, 8 de batata-doce, 10 de feijão e feijão-vagem, 25 de Capsicum e 6 de tomate. Foram calculados o fator de reprodução e o índice de reprodução, e os genótipos foram classificados quanto ao grau de resistência ao nematoide. Foram observados níveis moderados de resistência na cultivar de feijão Aporé e nos acessos de pimenta, BGH-433 e BGH-4285, e de pimentão, PIM-031, PIX-022I-31-07-02 e PIX-022I-31-13-01. Todos os genótipos de tomate são suscetíveis a M. enterolobii. As cultivares de alface Julia, Hortência, Verônica, Grand Rapids e Babá de Verão, e os clones de batata-doce UFLA07-49 e UFLA07-53 são muito resistentes ao nematoide. A resistência a M. enterolobii aparentemente é mediada por genes diferentes dos que conferem resistência a outras espécies e raças de Meloidogyne.

The objective of this work was to identify genotypes of lettuce, sweet potato, bean, tomato, and Capsicum resistant to the nematode Meloidogyne enterolobii (Syn. M. mayaguensis), and to classify them according to their resistance degree. The following were evaluated: 10 genotypes of lettuce, 8 of sweet potato, 10 of bean and snap bean, 25 of Capsicum, and 6 of tomato genotypes. Reproduction factor and reproduction index were determined, and genotypes were classified according to their resistance degree to the nematode. Moderate levels of resistance were observed in the bean cultivar Aporé and in the accessions of pepper BGH-433 and BGH-4285, and of sweet pepper, PIM-031, PIX-022I-31-07-02, and PIX-022I-31-13-01. All tomato genotypes are susceptible to M. enterolobii. Lettuce cultivars Julia, Hortência, Verônica, Grand Rapids and Babá de Verão, and sweetpotato clones UFLA07-49 and UFLA07-53 are very resistant to the nematode. Apparently, the resistance to M. enterolobii is controlled by different genes from the ones which confer resistance to other species and races of Meloidogyne.

Objetivou-se, no presente trabalho, avaliar o comportamento de linhagens de alface quanto à resistência ao nematoide das galhas Meloidogyne javanica, identificando a provável existência de linhagens homozigotas para o caráter. Foram utilizados como tratamentos cinco linhagens F4 e seis linhagens F5, juntamente com as testemunhas 'Grand Rapids' (resistente) e 'Regina 71' (suscetível), além da cultivar de tomateiro Santa Clara. A semeadura foi feita em bandejas de poliestireno expandido, sendo o substrato infestado com ovos de M. javanica, na proporção de 30 ovos cm-3 de substrato. Aos quarenta e sete dias após a infestação, cada planta foi avaliada individualmente quanto aos seguintes caracteres: índice visual de galhas, número de ovos, fator de reprodução e índice de reprodução. Cada linhagem foi comparada com as testemunhas 'Regina 71' e 'Grand Rapids', para cada característica, através do teste de Dunnett (5%), obtendo-se a significância em relação a cada uma das testemunhas, permitindo a classificação de cada linhagem como homozigota resistente, homozigota suscetível ou segregante. Pelos resultados obtidos conclui-se que seis linhagens (AFX 018C 002 23 15, AFX 018C 002 23 22, AFX 018C 005 42 20, AFX 018C 005 44 22, AFX 018C 005 44 28 e AFX 022B 010 31) foram consideradas homozigotas resistentes para as características avaliadas, podendo ser utilizadas como novas fontes de resistência ao M. javanica em programas de melhoramento de alface.

The objective of the present work was to evaluate the behavior of lettuce lineages as for resistence to nematode from the Meloidogyne javanica root-knots, identifying probable existence of homozigote lineages for the characteristics. Five F4 and six F5 lineages were used as treatments together with the controls 'Grand Rapids' (resistent) and 'Regina 71' (susceptible), apart from the Santa Clara tomato plant cultivar. The sowing was done over expanded polystyrene trays with the substrate infested by M. javanica eggs in the proportion of 30 eggs cm-3 of substrat. At 47 days after infestation, each plant was evaluated individually as for the following characteristics: visual level of root-knots, number of eggs, level and factor of reproduction. Every lineage was compared to the 'Regina 71' and 'Grand Rapids' for each characteristic, through Dunnett (5%) test, obtaining the significance in relation to each control, allowing the classification of each lineage as resistant homozigote, susceptible homozigote or segregated. The results obtained showed that six lineages (AFX 018C 002 23 15, AFX 018C 002 23 22, AFX 018C 005 42 20, AFX 018C 005 44 22, AFX 018C 005 44 28 and AFX 022B 010 31) were considered resistant homozigote for the evaluated characteristics, and maybe being used as new sources of resistance to M. javanica in lettuce breeding program.

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 x 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1' = ABX-037G-77-03-05-04-08-bulk, 2' = ABX-037G-77-03-05-02-11-bulk, 3' = Clarice and 4' = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F1 hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.

O objetivo deste trabalho foi selecionar clones de batata-doce (Ipomoea batatas) resistentes à raça 1 de Meloidogyne incognita e avaliar a eficiência do método de seleção empregado, pela estimação dos coeficientes de variação genética e ambiental e das herdabilidades no sentido amplo. Foram utilizados 123 genótipos de batata-doce, entre os quais quatro cultivares comerciais - Brazlândia Rosada, Brazlândia Roxa, Brazlândia Branca e Palmas -, e 119 acessos previamente selecionados no programa de melhoramento vegetal da Universidade Federal de Lavras. O delineamento experimental utilizado foi o de blocos aumentados, com três tratamentos comuns: as cultivares de batata-doce Brazlândia Branca e Palmas, e a cultivar de tomate Santa Clara, suscetível ao nematoide. A classificação dos níveis de resistência foi realizada de acordo com o fator de reprodução do nematoide e o índice de reprodução relativo à cultivar Santa Clara, de tomateiro. A relação entre os coeficientes de variação genética e ambiental e as herdabilidades no sentido amplo foram altas, tanto para o fator de reprodução quanto para o índice de reprodução dos nematoides, o que demonstra a eficiência do método empregado para a seleção de genótipos resistentes. Foram identificados 57 genótipos promissores de batata-doce, resistentes à raça 1 de M. incognita, e selecionados para continuar no programa de melhoramento.

The objective of this work was to select sweetpotato (Ipomoea batatas) resistant clones to Meloidogyne incognita race 1, and to assess the efficiency of the selection method deployed, through the estimation of genetic and environmental coefficients of variation, and broad-sense heritabilities. Genotypes assessed comprised 123 sweetpotato entries altogether, including four commercial cultivars - Brazlândia Rosada, Brazlândia Roxa, Brazlândia Branca, Palmas - and 119 clones previously selected by the Universidade Federal de Lavras sweetpotato breeding program. The experimental setup was a an augmented block design, using three common treatments: the sweetpotato cultivars Brazlândia branca and Palmas, and the nematode-susceptible tomato cultivar Santa Clara. Nematode resistance levels were defined both by the nematode reproduction factor and by the nematode reproduction index relative to tomato cv. Santa Clara. The ratio between genetic and environmental coefficients of variation and the broad-sense heritability estimates were high, for both nematodes reproduction factor and reproduction index, indicating that the selection method deployed was efficient for the selection of resistant genotypes. Fifty-seven sweetpotato clones were identified as resistant to M. incognita race 1, and selected to continue in the sweetpotato breeding program.

O objetivo deste trabalho foi avaliar a capacidade combinatória de linhagens de tomateiro com hábito de crescimento determinado, com resistência múltipla a espécies dos gêneros Begomovirus e Tospovirus, e identificar combinações híbridas superiores. O experimento foi realizado em casa de vegetação, com 14 híbridos obtidos do cruzamento de sete linhagens femininas (grupo I) com duas linhagens masculinas (grupo II), em um dialelo parcial. As seguintes características agronômicas foram avaliadas: produção total, produção precoce, massa média de frutos, formato, firmeza inicial e firmeza na meia-vida. As linhagens genitoras TOM-680 e TOM-682, do grupo I, se destacaram por exibir as maiores estimativas de capacidade geral de combinação (CGC) quanto às características produção total, produção precoce e massa média de frutos, enquanto a linhagem TOM-585 se destacou quanto aos maiores valores de produção total e massa média de frutos. No grupo II, a linhagem TOM-698 apresentou estimativas superiores de CGC para as características de produção total, produção precoce, massa média dos frutos e firmeza inicial dos frutos. O híbrido TOM-682xTOM-698 apresenta as maiores estimativas de capacidade geral e específica de combinação para produção total, produção precoce e meia-vida da firmeza, e é o genótipo mais promissor entre os materiais testados.

The objective of this work was to evaluate the combining ability of determinate-growth-habit tomato inbred lines with multiple resistance to Tospovirus and Begomovirus species, ant to identify superior hybrid combinations. The experiment was carried out in greenhouse, with 14 hybrids obtained from crosses of seven lines of the group I (female parents) with two lines of the group II (male parent), in a partial diallel. The following agronomical traits were assessed: total production, early production, mean fruit mass, shape, initial firmness and half life firmness. The parental lines TOM-680 and TOM-682, from group I, stand out with the largest general combining ability (GCA) concerning total production, early production and average fruit mass, while line TOM-585 stood out as to higher values of total production and average fruit mass. In group II, TOM-698 showed higher estimates of GCA as to total production, early production, average fruit mass and initial consistence of the fruits. The hybrid TOM-682xTOM-698 had the highest estimate of general and specific combining ability to total production, early production and average fruit mass, and it is the most promising genotype among the materials tested.