Abstract Species of the genus Cynodon are among the most cultivated forage crops in the world due to their high yield and nutritional quality, and its use in cattle feeding has been associated with gains in animal weight and increased milk production. The objective of this study was to model covariance structures in Cynodon spp. clones and study the changes in ranking of the selected genotypes, since it is believed that affects the ranking of genotypes. A total of 202 genotypes were evaluated in an experiment conducted in an augmented block design with four replications and four harvests. The genotypes were assessed for plant height, green weight, percentage of dry matter, and plant vigor. Nineteen repeated measures models with different covariance structures were tested. The best-fitted model adopts the CORH covariance structure for the genetic effects. Correct modeling of the covariance structure affected the ranking of genotypes in all variables evaluated. quality production spp 20 harvests height matter vigor tested bestfitted best fitted effects 2

Abstract We aimed to measure the efficiency of visual selection of plant vigor for green biomass production of U. ruziziensis using single- and multitrait approaches to maximize the predictive accuracy of the genetic value. The green biomass production and plant vigor of 254 U. ruziziensis clones were measured over nine evaluation cuttings to determine the efficiency of these approaches for production improvement. Individual and multicutting analyses were performed under single-trait and multitrait approaches using mixed models. The efficiency of visual selection was assessed by measuring plant vigor based on direct and indirect genetic gains. Plant vigor showed a high genetic association with green biomass and could be selected for production, especially in the initial phases of breeding programs. The multitrait approach was superior to the single-trait approach in predicting the genetic value of the clones, and it can be used in U. ruziziensis breeding programs.

ABSTRACT. The breeding program of Urochloa ruziziensis evaluates many genotypes in initial phases. Evaluations through grades might make the selection less costly. The aim of this study was to verify the efficiency of visual selection for green biomass yield in relation to different selection strategies, such as mass selection by phenotypic mean, BLUP (Best Linear Unbiased Prediction) and at random. For this purpose, 2,309 regular genotypes were evaluated in an augmented block design in two cuts. The evaluators gave grades for plant vigor, and later, the plots were measured for green biomass yield. The coincidences of the selected genotypes were estimated by different selection strategies. Then, 254 clones of the genotypes selected in different strategies were evaluated in a clonal test in a triple lattice design in four cuts. The statistical analyses were performed in SAS using the Mixed procedure. The regular genotype level and clone-mean basis heritabilities were 31.16 and 62.91%, respectively, for green mass yield. The expected selection gains were 21.09% (visual), 25.43% (phenotypic mean), and 27.5% (BLUP). Moreover, the realized heritabilities for these strategies were 15.58, 11.87, and 15.86%, respectively, which might be associated with genotype by environment interaction. Therefore, the visual selection could be a useful strategy in initial phases of a U. ruziziensis breeding program because the efficiency was moderate to high in relation to phenotypic mean and BLUP.

Abstract Forage plant breeders often use visual scores to assess agronomic traits because of the costs associated with in-depth phenotyping in the initial stages of breeding cycles. The aim of this study was to investigate the impact of the number of graders on the effectiveness of indirect selection of high-yielding genotypes and determine an optimal number of graders in the early-stage trials of Urochloa ruziziensis. For that purpose, five graders assessed 2.219 U. ruziziensis genotypes in an augmented block design. Biomass production and vigor scores were evaluated in two cuts and were analyzed using a linear mixed model approach. Vigor scores were analyzed considering each grader's score and the combinations of two, three, four, and five graders. Genetic variance was significant for both traits. Visual evaluation was effective in identifying productive genotypes based on the statistical criteria. The optimal number of graders for indirect selection of high-yielding U. ruziziensis genotypes is three.

RESUMO A grama estrela africana (Cynodon nlemfuensis Vanderyst) é considerada excelente forrageira. Contudo, há poucas informações disponíveis sobre o manejo de plantas daninhas em áreas de grama estrela. Dois experimentos foram realizados em 2017 e 2018 para avaliar a resposta da grama estrela africana a herbicidas pós-emergentes. Os tratamentos foram: 2,4-D (1.340,0 g ea ha-1), 2,4-D + picloram (720,0 + 192,0 g ea ha-1 + 0,3% v/v adjuvante não iônico), fluroxypyr + picloram (80,0 + 80,0 g ea ha-1 + 0,3% v/v de óleo mineral), fluroxypyr + aminopiralide (160,0 + 80,0 g ea ha-1 + 0,3% v/v de óleo mineral), fluroxypyr + triclopyr (320,0 + 960,0 g ea ha-1 + 0,3% v/v de óleo mineral), bentazon (720,0 g ia ha-1 + 0,5% v/v de óleo mineral), imazapyr (25,0 g ia ha-1), metano arseniato ácido monossódio (MSMA) (1.440,0 g ia ha-1 + 0,1% v/v adjuvante não iônico), atrazina + S-metolachlor (1480,0 + 1.160,0 g ia ha-1), atrazine + tembotrione (1.000,0 + 100,8 g ia ha-1 + 0,3% v/v óleo mineral) e a testemunha sem aplicação de herbicida. Os tratamentos mais fitototóxicos para grama estrela africana foram fluroxypyr + amininopiralide, fluroxypyr + triclopyr e atrazina + tembotrione. O rendimento de matéria seca das plantas de grama estrela-africana não foi prejudicado pela aplicação de 2,4-D, 2,4-D + picloram, bentazon, imazapyr, MSMA e atrazina + S-metolachlor. Esses herbicidas podem ser considerados tratamentos potenciais no manejo de pastagens formadas por grama estrela africana.

ABSTRACT Cynodon nlemfuensis Vanderyst, commonly called African star grass, is excellent forage in pasture formation and herd feeding. However, little information is available regarding weed management in areas of star grasses. Two field experiments were carried out in 2017 and 2018 to evaluate the response of African star grass to postemergence herbicides. The treatments applied were as follows: 2,4-D (1,340.0 g ae ha-1); 2,4-D + picloram (720.0 +192.0 g ae ha-1 + 0.3% v/v nonionic surfactant); fluroxypyr + picloram (80.0 + 80.0 g ae ha-1 + 0.3% v/v mineral oil); fluroxypyr + aminopyralid (160.0 + 80.0 g ae ha-1 + 0.3% v/v mineral oil); fluroxypyr + triclopyr (320.0 + 960.0 g ae ha-1 + 0.3% v/v mineral oil); bentazon (720.0 g ai ha-1 + 0.5% v/v mineral oil); imazapyr (25.0 g ai ha-1); monosodium methyl arsenate (MSMA) (1,440.0 g ai ha-1 + 0.1% v/v nonionic surfactant); atrazine + S-metolachlor (1,480.0 + 1,160.0 g ai ha-1); atrazine + tembotrione (1,000.0 + 100.8 g ai ha-1 + 0.3% v/v mineral oil) and a control without herbicide application. The most phytotoxic treatments for the African star grass plants were fluroxypyr + amininopyralid, fluroxypyr + triclopyr and atrazine + tembotrione. The dry matter yield of star grass plants was not reduced by the applications of 2,4-D, 2,4-D + picloram, bentazon, imazapyr, MSMA and atrazine + S-metolachlor. These herbicides can be considered potential practices in African star grass crop management.

Abstract Pasture is the main food source for more than 200 million cattle heads in Brazil. Although Brazilian forage breeding programs have successfully released well-adapted, high-yielding cultivars over the years, the use of genomic tools in these programs is currently limited. These tools are required to tackle the main challenges for tropical forage breeding in Brazil. In this context, this notes lists the main research priorities raised at the workshop “Breeding Forages in the Genomic Era”, which are necessary to accelerate the use of genomic tools for next-generation breeding of tropical forages and allow breeders to increase genetic gains. Additionally, an online discussion forum (hosted at http://www.cnpgl.embrapa.br/genfor) has been launched to strengthen collaborations among research groups. The research priorities and more synergistic collaborations will assist researchers and decision-makers in delivering a sustainable increase in production of animal products, especially beef and milk, which are required to feed a rising world population.

RESUMO: O objetivo deste estudo foi avaliar a divergência nutricional de clones de Brachiaria ruziziensis através da composição química e cinética de fermentação ruminal in vitro. Os tratamentos consistiram de 23 clones de Brachiaria ruziziensis (15, 16, 46, 174, 411, 590, 651, 670, 768, 776, 844, 859, 950, 965, 970, 975, 1067, 1093, 1296, 1765, 1806, 1894 e 1972), e as testemunhas Brachiaria ruziziensis cv ‘Kennedy’, Brachiaria brizantha cv ‘Marandu’ e a Brachiaria decumbens cv ‘Basilisk’, colhidas com 27 dias de rebrota. O delineamento experimental utilizado foi o de blocos casualizados, com 26 tratamentos (genótipos) e três repetições. A avaliação da divergência nutricional foi realizada utilizando-se a análise de componentes principais e agrupamento aglomerativo hierárquico. Com base nas seguintes variáveis discriminatórias: digestibilidade in vitro da matéria seca; fibra em detergente neutro; lignina; proteína bruta; taxa de degradação de carboidratos não fibrosos e; taxa de degradação de carboidratos fibrosos. A avaliação da divergência nutricional dos clones de B. ruziziensis baseou-se nos dois primeiros componentes principais (DIVMS e FDN), explicando 96.2% da variância total. As variáveis de menor contribuição para a discriminação dos clones foram as taxas de degradação dos carboidratos fibrosos e não fibrosos. Na análise de agrupamento aglomerativo hierárquico foram identificados cinco grupos distintos, em que o grupo V, formado pelos clones 46, 768 e 1067 destacou-se em relação aos demais por apresentar valores superiores de digestibilidade in vitro da matéria seca.

ABSTRACT: The aim of this study was to evaluate the nutritional diversity of Brachiaria ruziziensis clones through chemical composition and in vitro kinetics of ruminal fermentation. Twenty three clones of Brachiaria ruziziensis were used (15, 16, 46, 174, 411, 590, 651, 670, 768, 776, 844, 859, 950, 965, 970, 975, 1067, 1093, 1296, 1765, 1806, 1894 and 1972) and Brachiaria ruziziensis cv. ‘Kennedy’, Brachiaria brizantha cv. ‘Marandu’ and Brachiaria decumbens cv. ‘Basilisk’ as controls within 27 days of harvesting. The experimental design used randomized blocks with 26 treatments (genotypes) and three replications. Evaluation of the nutritional divergence was performed using principal components analysis, based on the following discriminatory variables: in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), lignin, crude protein (CP), degradation rate of non-fibrous carbohydrates (KdNFC) and degradation rate of fibrous carbohydrates (KdFC). The evaluation of the nutritional diversity of Brachiaria genotypes was based on the two main components (IVDMD and NDF), which explains 96.2% of the total variance Variables of lower contribution to the discrimination of the clones were as degradation rates of the fibrous and non-fibrous carbohydrates. In the agglomerative hierarchical grouping analysis, five distinct groups were identified, where V group, formed by clones 46, 768 and 1067 have higher values of IVDMD compared to the other clones.

O objetivo deste trabalho foi avaliar a necessidade de bordadura e estimar o tamanho ótimo de parcela em experimentos para avaliação de Urochloa ruziziensis. Foram avaliadas a altura das plantas e a produção de massa verde de oito progênies de meio-irmãos de U. ruziziensis, em dois cortes. Utilizou-se o delineamento de blocos ao acaso, com quatro repetições e parcelas de 16 m². Cada parcela foi subdividida em 32 estratos de 0,5 m², sendo cada estrato considerado como uma unidade básica. Para determinar a necessidade de bordadura, foi realizada análise de variância, tendo-se considerado a posição da unidade básica na parcela. As estimativas do tamanho ótimo da parcela foram realizadas pelo método da máxima curvatura do coeficiente de variação e pelo método da reamostragem. O uso de bordaduras não altera o desempenho médio e a classificação das progênies de meio-irmãos avaliadas. O emprego de parcelas com 3 m² é suficiente para obter boa precisão experimental em experimento com progênies de meio-irmãos de U. ruziziensis.

The objective of this work was to assess the need for a border area and to estimate the optimum plot size in experiments for the evaluation of Urochloa ruziziensis. Plant height and green mass production of eight half-sib progenies of U. ruziziensis were evaluated in two cuttings. A randomized complete block design was used, with four replicates and 16 m² plots. Each plot was subdivided into 32 strata of 0.5 m², with each stratum being considered as a basic unit. To determine the need for a border area, analysis of variance was carried out considering the position of the basic unit in the plot. Estimates of optimum plot size were made by the maximum curvature of the coefficient of variation method and by the resampling method. The use of borders does not affect the mean performance and classification of the half-sib progenies evaluated. The use of 3 m² plots is enough to obtain good experimental accuracy in an experiment with half-sib progenies of U. ruziziensis.

As cultivares de batata plantadas no Brasil são praticamente todas de origem européia e não são completamente adaptadas às condições tropicais do Brasil. O objetivo deste trabalho foi estimar os ganhos genéticos com três ciclos de seleção recorrente visando à tolerância ao calor em batata. A população base deste estudo foi formada por cinco clones brasileiros e cinco clones tolerantes ao calor. Nas safras de inverno de 2006 e das águas de 2007 foram avaliados 103 clones, sendo oito da população base, 29 do primeiro ciclo, 32 do segundo e 30 do terceiro ciclo de seleção recorrente e mais quatro cultivares testemunhas. Os ganhos genéticos para caracteres dos tubérculos na média das duas safras foram de 37,8 % (produtividade), 13,0 % (peso médio), 32,4 % (porcentagem de graúdos), 0,8 % (peso específico) e 16,6 % (nota de aparência). Observaram-se, ainda, redução na porcentagem de desordens fisiológicas (embonecamento e rachaduras).

Practically all potato cultivars grown in Brazil are native to Europe and not fully adapted to the tropical conditions. The purpose of this study was to estimate the genetic gains of three cycles of recurrent selection for heat tolerance in potato. The base population in this study consisted of five Brazilian and five heat-tolerant clones. In the winter of 2006 and rainy growing season of 2007 103 clones were evaluated (eight clones of the base population, 29 of the first cycle, 32 and 30 of the second and third recurrent selection cycle, respectively, and four control cultivars). The genetic gains for tuber traits in both growing seasons were 37.8 % (yield), 13.0 % (weight), 32.4 % (percent of large tubers), 0.8 % (tuber specific gravity) and 16.6 % (general tuber appearance). The percentage of physiological disorders (second-growth tubers and cracking) was also reduced by selection.

As cultivares de batata no Brasil geralmente apresentam ciclo vegetativo de 90 a 110 dias, sendo bem mais longo em países de clima temperado, podendo chegar até 150 dias. O ciclo vegetativo longo nestes países proporciona maior produtividade e constitui-se em alternativa para aumento da produção de tubérculos sob condições tropicais. Os objetivos deste trabalho foram avaliar o potencial da seleção para aumentar ou diminuir o ciclo vegetativo da batata e verificar a relação entre a duração do ciclo vegetativo e a produção de tubérculos em condições tropicais. Na primeira geração clonal foram avaliados a produção de tubérculos e o ciclo vegetativo de 1.561 genótipos oriundos de 22 famílias clonais. Na segunda geração clonal foram avaliadas as mesmas características em 320 genótipos selecionados para ciclo vegetativo precoce, intermediário e tardio. A seleção nas gerações iniciais foi eficiente, tanto para diminuir permitiu obter maior ganho do que a seleção entre famílias. Os genótipos mais tardios foram mais produtivos que os mais precoces.

Potato cultivars in Brazil generally present a growth cycle duration ranging from 90 to 110 days, whereas in countries located in temperate climate it can reach up to 150 days. Longer vegetative growth cycle in these countries confer higher tuber yield and, in tropical countries it also could be an alternative to increase tuber yield. In this work we evaluated the selection potential for longer or shorter growth cycle duration of potato clones and we determined the relationship between growth cycle duration and tuber yield. In the first clonal generation tuber yield and growth cycle duration were evaluated on 1561 genotypes derived from 22 clonal families. In the second clonal generation, the same traits were evaluated on 320 genotypes selected for earliness, intermediate and late vegetative cycle. Selection in the initial generations was efficient both to decrease and to increase the growth cycle duration. The selection for growth cycle based on individual clones allowed higher gains than the selection among families. The latest genotypes were more productive than the earliest genotypes.

A seleção precoce de clones que possuam níveis elevados de matéria seca e baixos teores de açúcares redutores é uma necessidade nos programas de melhoramento para a qualidade de processamento da batata (Solanum tuberosum L.) na forma de palitos fritos ou chips. A seleção precoce tornou-se possível com a utilização de marcadores genéticos, visto que permitem a identificação precisa de indivíduos superiores. Assim, procura-se cada vez mais encontrar marcadores capazes de caracterizar tais indivíduos e utilizá-los via seleção assistida. O objetivo deste trabalho foi avaliar a eficiência da seleção assistida, utilizando os marcadores identificados por ANDREU (2004) que estariam associados ao teor de matéria seca e açúcares redutores em tubérculos de batata. Clones provenientes de 20 famílias foram avaliados nas gerações de plântula (P), primeira geração clonal (C1) e segunda geração clonal (C2). As estimativas das correlações simples para os caracteres entre gerações foram significativas, porém, baixas, confirmando a inviabilidade de se efetuar a seleção precoce nas primeiras gerações com base apenas em informações fenotípicas. Os marcadores utilizados forneceram um total de 16 marcas. Pela regressão múltipla stepwise, apenas sete dessas marcas tiveram associação com os caracteres estudados. Além disso, nenhuma marca associada ao teor de matéria seca de tubérculos na geração C1 teve associação significativa na geração C2. Isso também foi observado com o teor de açúcares redutores, o que é um indicativo da interação QTLs x ambientes. A seleção assistida não se mostrou eficiente em relação à fenotípica em nenhum dos casos avaliados, portanto, não sendo útil em uma possível seleção precoce. Esses resultados indicam que tais marcadores não estão próximos aos genes controladores dos caracteres desejados, sendo necessária a identificação de novos marcadores mais associados que possibilitem maior eficiência da seleção assistida.

Early generation selection for clones with high content of tuber dry matter and low levels of reducing sugars is required for potato (Solanum tuberosum L.) processing. Selection of superior clones at early generations became possible with the deployment of genetic markers, and can precisely identify the superior individuals. Therefore, it is necessary to identify genetic markers closely linked to genes of interest to do assisted selection. The aim of this research was to evaluate the efficiency of marker assisted selection with genetic markers previously identified by ANDREU (2004), which are assumed to be associated with dry matter and reducing sugars content in potato tubers. Clones from 20 families were evaluated during the seedling generation (S), first clonal generation (C1) and second clonal generation (C2). The estimated coefficients of correlation for all traits among generations were significant, even though of low magnitude, confirming that selection at early generation based only on phenotypic traits is inviable. A total of sixteen bands were amplified using these markers. However, by multiple stepwise regression, only seven of these bands showed association with the evaluated traits. Moreover, no markers associated with dry matter and reducing sugars content in the C1 were significantly associated with these traits in the C2, suggesting the existence of QTLs x environment interactions. The marker assisted selection resulted less efficient than the phenotypic selection in all cases studied, and thus is not recommended for early generation selection of clones for the processing industry. These results suggest that the markers used are not closely linked to the genes controlling the traits most important for processing. Therefore, it is important to identify new markers closely linked with such traits of interest that could improve the efficiency of marker assisted selection.

A seleção precoce em batata tem sido avaliada há várias décadas, tendo em vista a importância em discriminar e selecionar clones promissores já nas primeiras gerações. Na tentativa de contornar a baixa eficiência da seleção precoce de clones individuais para caracteres de baixa herdabilidade, esforços estão sendo despendidos na avaliação do progresso genético com a utilização de famílias nas primeiras gerações. Conduziu-se este trabalho, com os objetivos de mensurar a interação entre famílias e ambientes e avaliar o progresso genético com a seleção precoce. Foram avaliadas 22 famílias e duas testemunhas em três locais, em Minas Gerais, no delineamento experimental de blocos casualizados, com três repetições. Foram realizadas análises de variância conjunta, de correlação e estimados os progressos genéticos. Houve interação famílias x locais altamente significativas somente para o caráter peso específico de tubérculos. O ganho genético esperado com a seleção na média dos ambientes é mais efetivo para a produção de tubérculos. Os ganhos esperados com a seleção na média dos ambientes são inferiores aos ganhos com a seleção realizada no próprio ambiente, porém, permite identificar famílias com ampla adaptação.

Early selection of potato clones has been evaluated for many decades with the aim of discriminating and selecting promising genotypes in the very beginning of the breeding program. In an attempt to surpass the low selection efficiency for characters with low heritability, efforts have been made in the evaluation of genetic progress using first generation families. The purposes of this study were to measure the interaction of families with the environments and to evaluate the efficiency of early generation selection of the families. Twenty-two families and two control cultivars were evaluated in three locations in Minas Gerais state, Brazil. The experimental design was a randomized complete block design with three replications. Combined analyses of variance were performed and estimates of correlations and genetic progress were obtained. Significant interaction of families x environments was observed only for the tuber specific weight. The expected genetic gain based on the selection of the environment average was more effective for the tuber yield. The expected genetic gain based on the selection of the environmental average was lower than the direct selection performed on each environment, but it allows the identification of broadly adapted families.

Os objetivos do trabalho foram avaliar os processos de crescimento, de tuberização e de partição de matéria seca em tubérculos de clones de batata precoces e tardios ao longo do ciclo vegetativo. Avaliou-se, ainda, a viabilidade do uso desses caracteres morfofisiológicos para a seleção de clones mais adaptados às condições tropicais. O trabalho foi desenvolvido em Lavras (MG), na safra das águas (agosto a dezembro de 2005). Os clones tardios foram mais produtivos que os precoces, devido ao crescimento mais vigoroso, à maior longevidade da área foliar fotossinteticamente ativa, à maior taxa de tuberização e ao período mais longo para enchimento de tubérculos. Os teores de clorofila a, b e total, a área foliar, a duração da área foliar, a taxa de crescimento relativo e a taxa assimilatória líquida para os tubérculos foram relevantes na diferenciação dos clones tardios e precoces. Sugere-se como estratégia possível para aumentar a produtividade da cultura da batata em regiões tropicais, a seleção de clones com ciclo vegetativo mais longo.

The objective of this research was to evaluate the growth, tuberization and dry matter partitioning to tubers of early and late potato clones during the vegetative growth. Besides, it was studied the viability for using morphophysiological traits as parameters to select clones more adapted to tropical conditions. The study was conducted in Lavras, Minas Gerais State, Brazil during the rainy season (August to December of 2005). Late clones were more productive than early clones at the end of the growth cycle, due to the more vigorous growth, longer duration of the photosynthetically active leaf area, the greater tuberization speed and the prolongation of tuber bulking period. Results also suggest that the morphophisiological traits used in this study are important to evaluate clones more adapted to the tropical conditions. The following physiological traits were relevant to differentiate late and early clones and should be used in breeding programs aimed at obtaining clones more adapted to the tropical conditions: content of chlorophylls a, b and total of the upper canopy, leaf area, leaf area duration, relative growth rate, and net assimilation rate to tubers. The results of this study suggest that one strategy that could be used to increase potato tuber yield in the tropics is the selection for a longer growth cycle.

O objetivo deste trabalho foi avaliar a viabilidade do emprego isolado e simultâneo dos mutantes rin, norA, og c e hp em heterozigose, em genótipos de tomateiro, visando à melhoria da qualidade pós-colheita dos frutos. Foram avaliados 18 genótipos que diferem quanto às combinações entre estes locos em dois diferentes backgrounds (FloraDade e background experimental). Contrastes não ortogonais foram estabelecidos para quantificar os efeitos dos alelos mutantes, isoladamente ou combinados em um mesmo genótipo, em dois backgrounds, sobre a produção total e produção precoce de frutos, massa média, firmeza, coloração externa, teores de licopeno e betacaroteno dos frutos. Os alelos norA e rin em heterozigose, no background FloraDade, desaceleraram a taxa de perda de firmeza e reduziram os teores de licopeno e betacaroteno nos frutos maduros. As combinações heterozigotas entre o mutante rin e os mutantes norA, og c e hp aumentaram a firmeza dos frutos. O efeito do genótipo rin+/rin nor+/norA sobre a firmeza dos frutos foi o somatório dos efeitos individuais dos locos. O alelo rin mostrou-se, individualmente, mais eficiente do que norA, em prolongar a firmeza dos frutos. Os genótipos og c+/og c e hp+/hp, juntos ou isolados, aumentaram a coloração dos frutos rin+/rin. Recomenda-se a utilização dos genótipos rin+/rin nor+/norA no desenvolvimento de híbridos longa vida, buscando-se, contudo, backgrounds que sofram prejuízo menor sobre a coloração dos frutos e adicionando-se mutantes og c+/og c e hp+/hp.

The objective of this work was to assess the viability of single and simultaneous use of rin, norA, og c and hp as heterozygotes in tomato genotypes in order to improve post-harvest fruit quality. Eighteen genotypes differing in combinations among these loci in two backgrounds (Floradade and experimental background) were evaluated. Contrasts were used to quantify the effects of single and simultaneous application of mutant loci, in two different backgrounds, on the total and early fruit yield, fruit mean mass, fruit firmness, development of external fruit color, lycopene and beta-carotene fruit contents. The norA and the rin alleles, used as heterozygotes in the FloraDade background, delayed the fruit softening and reduced lycopene and beta-carotene contents of mature fruit. All heterozygous combinations between rin and the mutants norA, og c and hp increased fruit firmness. The effect of the rin+/rin nor+ /norA genotypes on fruit firmness was roughly the sum of the individual effects of each locus. The rin allele was more efficient than norA to keep fruit firmness. The og c+/og c and hp+/hp genotypes, singly or in combination, improved colour of rin fruits. The combination rin+/rin and nor+/norA can be used in breeding for long shelf life tomatoes; however, genotypic backgrounds where fruit colour is less adversely affected should be sought or, alternatively, the colour mutant heterozygotes og c+/og c and hp+/hp should be used.

O objetivo deste trabalho foi avaliar os atributos de produtividade, qualidade e conservação pós-colheita de tomates, para comparar os efeitos promovidos pelos alelos alcobaça (norª), nonripening (nor) e ripening inhibitor (rin) em heterozigose, isoladamente ou em duplas combinações, sobre frutos de tomateiros híbridos. Foram avaliados dez tratamentos: sete híbridos experimentais quase-isogênicos, com background FloraDade x Tropic de genótipos nor+/norª, rin+/rin, nor+/nor, nor/norª, nor+/norª rin+/rin e nor+/nor rin+/rin; e três testemunhas comerciais (Floradade, Tropic e Carmen F1). Contrariamente aos genótipos rin+/rin e nor+/nor, o genótipo nor+/norª não prolongou, significativamente, a firmeza dos frutos em pós-colheita. Os genótipos duplo-mutantes norª/nor, nor+/norª rin+/rin e nor+/nor rin+/rin foram eficientes em atrasar a perda de firmeza e a evolução da coloração dos frutos; os efeitos dos locos nor+/norª e rin+/rin, juntos, sofreram desvios significativos em relação à soma dos efeitos desses locos, quando atuaram separadamente, no sentido de intensificarem esses atrasos. O uso de híbridos heterozigotos, nas duplas combinações entre os locos norª, nor e rin, mostrou-se vantajoso por propiciar frutos firmes, com maior extensão da vida pós-colheita, em comparação com o uso dos híbridos portadores desses locos isoladamente. A qualidade dos frutos duplo-mutantes não foi limitada pelo atraso na evolução da coloração vermelha.

Thie objective of this work was to evaluate yield, quality and postharvest conservation of tomatoes, to compare the effects promoted by the alcobaça (norª), nonripening (nor) and ripening inhibitor (rin) alleles, in heterozygosis, singly or in double combinations on hybrid tomato fruits. Ten treatments were evaluated: seven experimental nearly isogenic hybrids of FloraDade x Tropic background or reciprocal with nor+/norª, rin+/rin, nor+/nor, nor/norª, nor+/norª rin+/rin and nor+/nor rin+/rin genotypes, and three commercial checks (FloraDade, Tropic and Carmen F1). Oppositely to the genotypes rin+/rin and nor+/nor, the genotype nor+/norª did not significantly extend the firmness of the fruits in postharvest. The double mutant genotypes norª/nor, nor+/norª rin+/rin and nor+/nor rin+/rin were efficient in delaying firmness loss and the evolution of fruits colouring; the effects of loci nor+/norª and rin+/rin, together, underwent significant deviations relatively to the sum of these loci effects, when acting singly, in the sense of enhancing those delays. Use of heterozygous hybrids in the double combinations among loci norª, nor and rin proved advantageous for providing firm fruits with a longer postharvest lifetime, as compared with the hybrids carrying these loci singly. The quality of double mutant fruits was not restricted by the delay in the evolution of red coloration.