ABSTRACT Tomato genotypes ( Solanum spp.) have genetic variability of most desirable features, such as resistance to biotic and abiotic stresses. However, incompatibility of crosses of wild genotypes with domesticated tomatoes, or even between wild genotypes, hinders the breeding process. Thus, knowledge of the reproductive biology of genotypes and conditions is necessary to maximize the success of artificial crossings. This study evaluated the compatibility of self-pollination, intra- and interspecific controlled crosses, stigma receptivity, and pollen viability in tomato genotypes. We used two commercial genotypes S. lycopersicum (‘RVTM08’ and ‘Redenção’) and seven accessions of wild tomato genotypes (‘AF 26970’, ‘LA-1401’, ‘AF 19684’, ‘LA-1967’, ‘PI-127826’, ‘PI-134417’, and ‘LA-716’). We evaluated all crosses and their reciprocals, besides the self-pollinations. The variables evaluated were fruit index (FI), number of seeds per fruit (SN), and seed germination percentage (GP). Stigma receptivity and grains’ pollen viability index (PVI) were also assessed. The results showed that ‘LA-1967’ was self-incompatible, had a low PVI, and generated fruit without seeds in most crosses. As female parents, ‘RVTM08’, ‘Redenção’, ‘AF 26970’, ‘LA-1401’, and ‘AF 19684’ showed higher FI and SN. There was a wide diversity of reproductive characteristics between the genotypes and crosses that did not influence GP. Compatibility of crosses in tomatoes is determined by the female parent choice and can be affected by stigma receptivity and the PVI.

Abstract The objective of this work was to evaluate the combining ability of S3 forage maize (Zea mays) progenies for traits related to forage yield and bromatological quality, with and without the ear, as well as to evaluate the ability of testers to discriminate progenies for these traits. The trials were carried out in the 2017/2018 and 2018/2019 crop seasons, in the municipality of Guarapuava, in the state of Paraná, Brazil. Topcross hybrids obtained from the crosses of 28 S3 maize progenies with three testers were evaluated. The following forage qualitative traits of the whole plant and of the plant without the ear were evaluated: neutral and acid detergent fibers, lignin, and in situ dry mass digestibility, as well as digestible dry mass yield of the whole plant. The progenies that stood out for forage qualitative traits were 85.1 and 42.1 for the whole plant and for the plant without the ear, respectively. For the qualitative and productive traits of whole-plant forage, progenies 91.1, 106.2, 126.2, 138.1, 152.1, 235.1, and 251.1 are promising to continue in the breeding program aiming to generate hybrids with a high yield and fiber quality. Testers LEM3 and AG8025 are efficient in discriminating progenies for forage yield and bromatological traits.

Resumo O objetivo deste trabalho foi avaliar a capacidade de combinação de progênies S3 de milho (Zea mays) forrageiro em relação a características relacionadas com o rendimento e a qualidade bromatológica da forragem, com e sem a espiga, bem como avaliar a capacidade de testadores para a discriminação das progênies para estas características. Os ensaios foram realizados nas safras de 2017/2018 e 2018/2019, no município de Guarapuava, no estado do Paraná, Brasil. Foram avaliados os híbridos topcross obtidos dos cruzamentos de 28 progênies de milho S3 com três testadores. As seguintes características qualitativas da forragem da planta inteira e da planta sem a espiga foram avaliadas: fibras em detergente neutro e ácido, lignina e digestibilidade in situ da massa seca, além do rendimento da massa seca digerível de toda a planta. As progênies que se destacaram quanto às características qualitativas da forragem foram 85.1 e 42.1 para a planta inteira e para a planta sem a espiga, respectivamente. Para as características qualitativas e produtivas da forragem da planta inteira, as progênies 91.1, 106.2, 126.2, 138.1, 152.1, 235.1 e 251.1 são promissoras para continuar no programa de melhoramento com vistas à geração de híbridos com altos rendimento e qualidade de fibra. Os testadores LEM3 e AG8025 são eficientes na discriminação de progênies para as características produtivas e bromatológicas das forragens.

Abstract This study aimed to apply, in unprecedented depth, a Bayesian approach to the non-linear regression model developed by Toler for evaluating the stability and adaptability of genotypes. Twenty-five soybean cultivars were evaluated in twenty-one plots across the midwestern of Brazil. A complete block design was employed, with three replications. The evaluated variable was grain yield. The proposed methodology was implemented in the R program by means of the BRugs package. The methodology was capable of differentiating the effect of the environment on soybean cultivars in terms of yield in the different environments, allowing exploration of the response of each genotype to environmental variations. Cultivars 6266RSF, NS6990, GD19I435, GD19I439, GD19C443, RC0496 and IA18661 presented good stability and general adaptability, being the most recommended for future evaluations. The other cultivars presented specific adaptability and high responsiveness to unfavorable environments. apply depth nonlinear non linear genotypes Twentyfive Twenty five twentyone twenty one Brazil employed replications package environments variations 6266RSF RSF NS6990 NS GD19I435 GDI GD I GD19I439 GD19C443 GDC C RC RC049 IA IA1866 evaluations NS699 GD19I43 GD19C44 RC04 IA186 NS69 GD19I4 GD19C4 RC0 IA18 NS6 GD19I GD19C IA1

RESUMO: A análise dos principais efeitos aditivos e interação multiplicativa é comumente utilizada na avaliação da interação genótipo x ambiente, porém, sua aplicação pode ser estendida para outros propósitos assim como realizado no presente trabalho em que utiliza esta técnica na seleção de linhagens, testadores e híbridos em topcrosses de milho. O objetivo deste trabalho foi determinar o efeito da interação linhagens x testadores por meio da análise dos principais efeitos aditivos e da interação multiplicativa, verificando sua eficiência na seleção de linhagens, testadoras e combinações híbridas em topcrosses. Os ensaios foram realizados nas safras 2015/16 e 2016/17, com delineamento em blocos completos, com três repetições. Trinta linhagens de milho S3 foram avaliadas em cruzamentos com os testadores AG8025, P30B39, MLP102, 60.H23.1 e 70.H26.1 formando 150 topcrosses híbridos. A característica avaliada foi a produtividade de grãos. A adaptabilidade e estabilidade de testadores e linhagens foram avaliadas pela metodologia de análise de efeitos aditivos principais e interação multiplicativa direcionada à interação testadores x linhagens. A linhagem 96.3 apresentou o desempenho mais homogêneo e o maior rendimento de grãos, considerando o cruzamento com todos os testadores em ambos os ambientes. O testador 70.H26.1 é considerado o mais estável e o mais recomendado para topcrosses. As melhores combinações específicas foram 96.3 x 70.H26.1 e 96.3 x 60.H23.1.

ABSTRACT: The analysis of main additive effects and multiplicative interaction is commonly used in the evaluation of the genotype x environment interaction, however, its application can be used for other purposes, as it is performed in the presentresearch, which uses this technique in the selection of inbred lines, testers and hybrids in maize topcrosses. Thisresearch determined the effect of the inbred lines x testers interaction through the analysis of main additive effects and multiplicative interaction, verifying their efficiency in the selection of inbred lines, testers and hybrid combinations in topcrosses. The trials were carried out in the 2015/16 and 2016/17 crop seasons, with a complete block design, with three replications. Thirty S3 maize inbred lines were evaluated in crosses with the AG8025, P30B39, MLP102, 60.H23.1 and 70.H26.1 testers forming 150 hybrids topcrosses. The trait evaluated was grain yield. The adaptability and stability of testers and inbred lines were evaluated by the methodology of analysis of main additive effects and multiplicative interaction directed to the interaction of testers x inbred lines. The 96.3 inbred line has the most homogeneous performance and the highest grain yield, considering the crossing with all testers in both environments. The 70.H26.1 tester is considered the most stable and the most recommended for topcrosses. The best specific combinations were 96.3 x 70.H26.1 and 96.3 x 60.H23.1.

ABSTRACT The objective of this study was to evaluate the effect of harvesting corn at different maturity stages for silage production combined with four storage periods, considering nutrient loss and the chemical composition of silage of the whole plant and also of grainless plants. The experiment was performed in a completely randomized design with a factorial arrangement of six maturity stages of corn [reproductive (R); R1 to R6] and four periods of silage storage (30, 60, 90, and 120 days). At stages R1 and R2, losses by effluents occurred more intensely when compared with the more advanced stages, whereas losses by gases showed the opposite behavior, with stage R6 responsible for the greatest losses. Stage R4 showed a stable dry matter (DM) content during the storage period, 42.08%, and had the lowest levels of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) for the whole plant silage. The ADL in the silage of grainless plant of stage R4 was not the lowest, but it was close to the first reproductive stages, being an important point, since the first reproductive stages can present a vegetative fraction of better quality. The highest DM volumes produced by area occurred in the most advanced stages; however, R5 obtained a greater reduction in volume over the days of storage (20.66 kg day −1 ). The production cost was lower at the advanced stages (R4, R5, and R6) when compared with the first reproductive stages (R1, R2, and R3), and in general, during the storage period the costs did not have great variations. Based on the chemical composition of the silages, DM losses during the storage period, the stability in the costs of DM ton over the days of storage, the R4 stage was the most suitable for silage production.

RESUMO A análise da divergência genética entre testadores e progênies associada à capacidade de combinação e parâmetros genéticos pode auxiliar na seleção de testadores para a avaliação do rendimento de grãos e características forrageiras em cruzamentos topcrosses, uma vez que são raros os testadores adequados para ambos os propósitos. O objetivo deste trabalho foi selecionar testadores adequados para a avaliação do rendimento de grãos e de características forrageiras em topcrosses com progênies S3 de milho com base na associação entre divergência genética, capacidade geral de combinação e parâmetros genéticos. Os experimentos foram conduzidos nas safras 2015/16 e 2016/17 em Guarapuava-PR. Foram avaliados 150 cruzamentos topcrosses entre 30 progênies S3 de milho e cinco testadores (os híbridos AG8025 e P30B39, as linhagens 60.H23.1 e 70.H26.1, e a mistura de linhagens MLP102). As características avaliadas foram altura de planta e de espiga, rendimento de grãos, rendimento de massa seca da forragem, teores de fibra em detergente neutro e fibra em detergente ácido e digestibilidade in situ da forragem. Não houve um único testador adequado para selecionar progênies quanto ao rendimento de grãos e características forrageiras simultaneamente. O testador 70.H26.1 é o mais recomendado para distinguir as progênies quanto ao rendimento de grãos. O testador 60.H23.1 é o mais recomendado para avaliar as características forrageiras das progênies. Não houve correlação linear entre divergência genética, capacidade geral de combinação dos testadores e parâmetros genéticos.

ABSTRACT Genetic divergence analysis among testers and progenies and the correlation of genetic distance with combining ability can be an important alternative to select maize progenies regarding grain yield and forage potential since testers suitable to both purposes are rare.The objective of this work was to select testers suitable for the evaluation of grain yield and forage traits is topcrosses with S3 progenies of maize based on the association between genetic divergence, general combining ability and genetic parameters. The experiments were carried out in the 2015/16 and 2016/17crop seasons in Guarapuava-PR. We evaluated 150 topcrosses among 30 S3 progenies and testers five testers (single hybrids AG8025 and P30B39, the elite inbred lines 60.H23.1 and 70.H26.1, and a mixture of inbred lines MLP102), The evaluated traits were plant height, ear height, grain yield, dry mass yield, neutral detergent fiber and acid detergent fiber andforage in situ digestibility. There was not a single suitable tester regarding grain yield and forage traitssimultaneously. The 70.H26.1 tester is the most recommended for grain yield. The 60.H23.1 tester is the most recommended for forage traits. There was not linear correlation between genetic divergence, general combining ability and genetic parameters.

ABSTRACT. Maize forage is commonly used as silage in milk and beef cattle livestock production systems. Despite the wide variety of maize hybrids with high potential for grain production, few available hybrids have been developed exclusively for forage aptitude. The present study aimed to select S3 maize progenies derived from the single hybrid AS1572 based on the combining ability of forage traits in topcrosses with testers AG8025, 70.H26.1, and MLP102. The 135 resulting topcross hybrids were assessed in partial diallel in Guarapuava and Rio Bonito do Iguaçu, Paraná State, Brazil. Were evaluated the contents of neutral detergent fiber (NDF, %DM) and acid detergent fiber (ADF, %DM), forage dry matter yield (DMY, t ha-1), and in situ digestibility of forage dry matter (DIG, %DM). For all evaluated traits, the variability allowed us to select superior progenies. Progenies 3.1, 22.1, and 39.1stood out in terms of NDF, ADF, and DIG, whereas progenies 47.1, 73.1, 79.1, and 90.2 were efficient in increasing the forage dry matter yield. The testers AG8025 and 70.H26.1, of narrow genetic base, are the best to explore genetic variability among progenies.

ABSTRACT Super sweet corn breeding must develop hybrids that fully meet the expectations of the market. In this sense, the determination of keytraits for the selection of sweetcorn genotypes is a fundamental condition for breeding success. The objective of this work was to identify key traits for the selection of promising and contrasting genotypes of super sweet corn. The experiments were carried out in Guarapuava (PR), in two sowing dates. Seventeen traits related to the yield and quality of the ear were evaluated. To perform the multivariate analysis, data were subjected to diagnosis of multicolinearity, analysis of canonical variables, genetic divergence, hierarchical clusters, factor analysis, and canonical correspondence analysis. Grain yield, yield of dehusked ears, and number of commercial ears were considered related key traits in the identification of promising super sweet corn genotypes. Hybrid D3-20 × D5-41 presented higher averages than the others, considering the yield related keytraits.

Resumo: O objetivo deste trabalho foi avaliar o desempenho produtivo, a adaptabilidade e a estabilidade de híbridos topcross de milho (Zea mays) em nove ambientes no Brasil, para selecionar linhagens, testadores e combinações híbridas promissoras para esses ambientes na segunda safra. Os experimentos foram instalados durante a segunda safra de 2017, em seis localidades no estado do Paraná e três no estado de Mato Grosso do Sul. Foram avaliados 66 híbridos simples, compostos por 33 linhagens cruzadas com 2 testadores. A estabilidade dos genótipos foi avaliada pelo método de Schmidt & Cruz e pela metodologia “additive main effects and multiplicative interaction” (AMMI). Também foram estimados os parâmetros genéticos e a capacidade geral de combinação dos testadores. O testador 2 é o mais adaptado para discriminar as linhagens em ambientes de segunda safra. As linhagens 12, 21, 23 e 32 são recomendadas para a obtenção de híbridos para cultivo na segunda safra, devido à sua boa adaptabilidade e estabilidade e ao seu alto rendimento nos cruzamentos em que participaram. Os híbridos HS123, HS223 e HS232 apresentam o melhor desempenho e são os mais recomendados para ambientes de segunda safra.

Abstract: The objective of this work was to evaluate the yield performance, adaptability, and stability of corn (Zea mays) topcross hybrids in nine environments in Brazil, in order to select inbred lines, testers, and promising hybrid combinations for these environments in the second crop season. The trials were carried out during the second crop season of 2017, in six sites in the state of Paraná and three in the state of Mato Grosso do Sul, Brazil. Sixty-six single-cross hybrids, made up of 33 inbred lines crossed with two testers, were evaluated. The stability of the genotypes was assessed by the Schmidt & Cruz method and by the additive main effects and multiplicative interaction (AMMI) methodology. In addition, the genetic parameters and the general combining ability of the testers were estimated. Tester 2 is the most adapted to discriminate inbred lines in the second-crop environments. Inbred lines 12, 21, 23, and 32 are recommended for obtaining hybrids to be cultivated in the second crop season due to their good adaptability and stability and high yield in the crosses in which they participated. The HS123, HS223, and HS232 hybrids present the best performance and are the most recommended for the second-crop environments.

RESUMO A exploração da variabilidade genética existente para características fisiológicas relacionadas com a produtividade e a qualidade da forragem de milho pode auxiliar no desenvolvimento de linhagens e híbridos superiores. O objetivo deste trabalho foi avaliar a capacidade geral e específica de combinação e a natureza dos efeitos genicos de características fisiológicas e químicas de genótipos de milho forrageiro. Foram avaliados dois grupos de genótipos e 16 híbridos resultantes dos cruzamentos em esquema de dialelo parcial 4x4. O grupo I foi constituído por dois híbridos comerciais (AG8025, P30B39) e duas linhagens elite (LEM2 e LEM3). O grupo II foi constituído por quatro linhagens experimentais oriundas de diferentes populações do programa de melhoramento do milho forrageiro da UNICENTRO. No total foram avaliados 24 tratamentos, constituídos pelos genótipos de ambos os grupos e os respectivos cruzamentos. As características avaliadas foram assimilação de CO2 (A), condutância estomática (gs), concentração interna de CO2 (Ci), transpiração (E), atividade calculada da Rubisco (A/Ci) e eficiência de uso da água (A/E). Foram obtidos os teores de fibra em detergente ácido (FDA), fibra em detergente neutro (FDN) e a digestibilidade in situ da forragem. Houve predomínio de efeitos gênicos não aditivos para a maioria das características químicas e fisiológicas. Os cruzamentos LEM2 x 203-218,3, LEM3 x 201-107,2, LEM2 x 101-7,2 e LEM3 x 101-7,2 se destacaram quanto à assimilação de CO2, sendo indicados para pesquisas futuras considerando as características fisiológicas. As linhagens 101-7.2 e 203-218.3 apresentaram alta concentração de alelos favoráveis para aumentar a eficiência da carboxilação, em que a linhagem 101-7.2 se destacou para NDF, ADF e DIG. A linhagem endogâmica 201-107.2 possui alta concentração de alelos favoráveis para eficiência do uso da água. Parâmetros fisiológicos podem auxiliar na seleção de linhagens e híbridos no melhoramento do milho forrageiro.

ABSTRACT The exploitation of the existing genetic variability for the physiological traits related to the yield and quality of maize forage can assist in the development of superior inbred lines and hybrids. The objective of this work was to evaluate the general and the specific combining ability and the nature of gene effects of physiological and chemical traits of forage maize genotypes. Two groups of genotypes and 16 hybrids resulting from a 4x4 partial diallel scheme were evaluated. Group I consisted of two commercial hybrids (AG8025, P30B39) and two elite inbred lines (LEM2 and LEM3). Group II consisted of four experimental inbred lines originated from different populations of forage maize breeding program. In total, 24 treatments were evaluated, formed by the genotypes of both groups and the respective crossings. The traits evaluated were: CO2 assimilation (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E), calculated activity of Rubisco (A/Ci) and efficiency of water use (A/E). Forage acid detergent fiber (ADF), neutral detergent fiber (NDF) and digestibility in situ were obtained. There was a predominance of non-additive gene effects for most of the chemical and physiological traits. Crossings LEM2 x 203-218.3, LEM3 x 201-107.2, LEM2 x 101-7.2 and LEM3 x 101-7.2 stood out regarding CO2 assimilation, and are indicated for future research considering the physiological traits. Inbred lines 101-7.2 and 203-218.3 presented high concentration of favorable alleles to increase carboxylation efficiency, in which inbred line 101-7.2 stood out for NDF, ADF and DIG. Inbred line 201-107.2 has a high concentration of favorable alleles for efficiency of water use. Physiological parameters can assist the selection of inbred lines and hybrids in maize breeding for forage purpose.

Resumo: O objetivo deste trabalho foi identificar genótipos de milho (Zea mays) com potencial forrageiro e avaliar a eficiência dos testadores em discriminar características forrageiras em cruzamentos topcrosses, ao se considerar a contribuição de genes aditivos e não aditivos. O experimento foi conduzido nas safras de 2015/2016 e 2016/2017, no delineamento de blocos ao acaso, com três repetições. Avaliaram-se 30 progênies S3 de milho em cruzamentos topcrosses com os testadores AG8025, P30B39, MLP102, 60.H23.1 e 70.H26.1. Foram avaliadas as seguintes características: produtividade de massa seca da forragem, fibra em detergente neutro, fibra em detergente ácido e degradabilidade da massa seca da forragem. As progênies 205.2, 159.6 e 199.2, nessa ordem, apresentaram o melhor desempenho para potencial forrageiro. Os testadores 60.H23.1 e 70.H26.1 melhor expressaram a variabilidade genética existente entre as progênies. Para todas as características nas duas safras, há o predomínio da ação de genes de efeitos não aditivos.

Abstract: The objective of this work was to identify corn (Zea mays) genotypes with forage potential and to evaluate the efficiency of testers to discriminate forage traits in topcrosses, considering the contribution of additive and nonadditive genes. The experiment was carried out in the 2015/2016 and 2016/2017 crop seasons, in a randomized complete block design with three replicates. Thirty S3 corn progenies were evaluated in topcrosses with the AG8025, P30B39, MLP102, 60.H23.1, and 70.H26.1 testers. The following traits were assessed: forage dry mass yield, neutral detergent fiber, acid detergent fiber, and forage dry mass degradability. Progenies 205.2, 159.6, and 199.2, in this order, presented the best performance for forage potential. Testers 60.H23.1 and 70.H26.1 better expressed the genetic variability between progenies. For all traits in both crop seasons, there is a predominance of the action of genes of nonadditive effects.

ABSTRACT. The objective of this study is to analyze the growth of wild species of tomato, of the cultivar Redenção and of the respective F1 hybrids of interspecific crossings. We evaluated six wild-type accessions (Solanum pimpinellifolium ‘AF 26970’, S. galapagense ‘LA-1401’, S. peruvianum ‘AF 19684’, S. habrochaites var. hirsutum ‘PI-127826’, S. habrochaites var. glabratum ‘PI-134417’, and S. pennellii ‘LA-716’) and the commercial cultivar Redenção (S. lycopersicum) together with their respective interspecific hybrids. In completely randomized blocks and plots subdivided by time (16, 28, 42, 56, 70, and 84 days after transplanting), we evaluated leaf area (LA), total dry matter (TDM), absolute growth rate (AGR), relative growth rate (RGR) and net assimilation rate (NAR). The distribution of assimilates in the different organs followed different patterns according to genotype. There was a greater accumulation of LA and TDM in the accessions ‘PI-127826’ and ‘PI-134417’ and in the hybrids ‘Redenção’ x ‘PI-127826’ and ‘Redenção’ x ‘PI-134417’. Due to a heterotrophic effect provided by the crossings, there were higher LA, TDM, AGR, RGR and NAR in hybrids than in parent plants. The accessions ‘PI-127826’ and ‘PI-134417’ presented a potential to be donor parents for obtaining tomatoes with a greater capacity of net assimilation and biomass accumulation.

Resumo: O objetivo deste trabalho foi estimar a temperatura-base para emissão de nós e determinação de plastocrono em espécies silvestres de tomateiro, na cultivar Redenção e em seus respectivos híbridos interespecíficos F1. Avaliaram-se os acessos silvestres Solanum pimpinellifolium AF 26970, Solanum galapagense LA-1401, Solanum peruvianum AF 19684, Solanum habrochaites var. hirsutum PI-127826, Solanum habrochaites var. glabratum PI-134417 e Solanum pennellii LA-716; a cultivar Redenção (Solanum lycopersicum); e os seus respectivos híbridos interespecíficos, nas datas de transplantio 22/12/2015, 12/2/2016 e 6/4/2016. A temperatura-base foi estimada com o método do menor quadrado médio do erro da regressão linear entre o número de nós e a soma térmica acumulada. O plastocrono para a haste principal e as três primeiras hastes laterais foi estimado com uso da temperatura-base. A temperatura base para emissão de nós e determinação do plastocrono variou entre 4,5 e 14,8°C. As espécies S. habrochaites var. hirsutum acesso PI-127826, S. habrochaites var. glabratum acesso PI-134417 e os respectivos híbridos com a cultivar Redenção apresentaram os menores valores de temperatura-base e plastocrono da haste principal, enquanto as demais espécies silvestres e os híbridos interespecíficos tiveram temperatura-base próxima à do tomateiro cultivado. As espécies silvestres e os híbridos interespecíficos de tomate mostram grande variação na temperatura-base para emissão de nós e determinação do plastocrono.

Abstract: The objective of this work was to estimate the base temperature for node emission and plastochron determination in wild species of tomato, in the Redenção cultivar, and in their respective interspecific F1 hybrids. The wild accessions Solanum pimpinellifolium AF 26970, Solanum galapagense LA-1401, Solanum peruvianum AF 19684, Solanum habrochaites var. hirsutum PI-127826, Solanum habrochaites var. glabratum PI-134417, and Solanum pennellii LA-716; the cultivar Redenção (Solanum lycopersicum); and their respective interspecific hybrids were evaluated, on the transplanting dates 12/22/2015, 2/12/2016, and 4/6/2016. The base temperature was estimated using the least mean squared error of the linear regression between the number of nodes and the accumulated thermal sum. The plastochron for the main stem and the first three lateral stems was estimated using the base temperature. The base temperature for node emission and plastochron determination varied from 4.5 to 14.8°C. The species S. habrochaites var. hirsutum accession PI-127826, S. habrochaites var. glabratum accession PI-134417, and their hybrids with the Redenção cultivar showed the lowest base temperatures and plastochron for the main stem, whereas the remaining wild species and interspecific hybrids had a base temperature near that of cultivated tomato. Wild species and interspecific hybrids of tomato show a great variation in base temperature for node emission and plastochron determination.

RESUMO. O objetivo deste trabalho foi avaliar o efeito da aplicação de fungicida sobre a podridão de grãos em híbridos comerciais de milho e a relação entre os grãos ardidos e a expressão da enzima lipoxigenase no grão, em espaçamento convencional de 0,70 m e reduzido de 0,45 m. Os tratamentos foram no esquema fatorial 3 x 8, com três formas de manejo com fungicida (Trifloxistrobina + Protioconazol) e oito híbridos de milho, sendo divididos em dois grupos (tolerantes e suscetíveis), com três repetições, totalizando 72 parcelas em cada ambiente (espaçamento convencional e reduzido), na safra agrícola 2013/2014. As seguintes caractrísticas foram avaliadas: porcentagem de grãos ardidos e expressão da enzima lipoxigenase (LOX) nos grãos. O fungicida reduziu a incidência de grãos ardidos, e a maior redução ocorreu nos híbridos suscetíveis, com duas aplicações, V8 e V8+VT. Houve maior expressão da enzima LOX em híbridos de milho pertencentes ao grupo tolerante aos fungos causadores de grãos ardidos. A aplicação do fungicida em duas aplicações, V8 (oito folhas) e VT (pendoamento), aumentou a intensidade da enzima LOX, mais evidente no espaçamento reduzido.

ABSTRACT. This study was carried out with the objective of evaluating the effect of fungicide application on grain rot in commercial maize hybrids and the relation between grain rot and the expression of lipoxygenase enzyme in grain in conventional row spacing of 0.70 m and reduced row spacing of 0.45 m. Treatments were made in a 3 x 8 factorial scheme, using three forms of management with fungicide (Trifloxystrobin + Prothioconazole) and eight maize hybrids divided into two groups (tolerant and susceptible) with three repetitions, totaling 72 plots in each environment (conventional and reduced spacing) in the 2013/2014 crop. The following characteristics were evaluated: grain rot percentage and lipoxygenase enzyme expression (LOX) in the grain. The hybrid and the fungicide utilized influenced the grain rot percentage. Grain rot percentage was reduced by the use of the fungicide, and the highest reduction was in susceptible hybrids with two applications, V8 and V8+VT. There was higher expression of LOX enzyme in maize hybrids that belong to the group tolerant of fungi that cause grain rot .The use of the fungicide in two applications, V8 (eight leaves) and VT (tasseling), increased the intensity of the LOX enzyme, which was more evident for the reduced spacing.

RESUMO. Objetivou-se avaliar o comportamento de 46 linhagens S4 de milho provenientes do cruzamento entre os híbridos comerciais Penta x P30F53 em topcrosses com o híbrido simples comercial Dow8460 (testador), mais as testemunhas (híbridos Penta, P30F53, Dow8460 e Status). A produtividade de grãos foi avaliada em dois ambientes em Guarapuava, estado do Paraná e houve efeito significativo de genótipos, ambientes e da interação genótipos x ambientes. Entre os híbridos topcrosses a produtividade de grãos variou de 8.416 a 13.428 kg ha-1. No ambiente 1 foram avaliadas características agronômicas da forragem e bromatológicas da silagem. A produtividade de massa verde da forragem variou de 48.767 a 87.714 kg ha-1e a produtividade de massa seca de 14.749 a 26.130 kg ha-1. Os teores de fibra em detergente neutro da silagem variaram de 44,85 a 58,45% e os teores de fibra em detergente ácido de 28,28 a 37,06%. O valor relativo da silagem oscilou entre 100,5 e 138,5. Os híbridos topcrosses HTC 109 e HTC 183 foram superiores considerando todo o conjunto de caracteres forrageiros e bromatológicos da silagem e, ainda, apresentaram elevada produtividade de grãos, indicando que suas respectivas linhagens S4 contribuíram com alelos favoráveis para as características avaliadas.

ABSTRACT. This study aimed to evaluate the performance of 46 maize lines (S4) obtained from crosses between the commercial hybrids Penta x P30F53 in topcrosses with the commercial simple cross hybrid Dow8460 (tester) and checks (hybrids Penta, P30F53, Dow8460 and Status). The grain yield was evaluated in two environments in Guarapuava, Paraná State, and the effects of genotype, environment and genotype x environment interaction were significant. The grain yield of the topcross hybrids ranged from 8,416 to 13,428 kg ha-1. The agronomic characteristics of the forage and the bromatological characteristics of the silage were evaluated in environment 1. The green mass yield of the forage ranged from 48,767 to 87,714 kg ha-1 and the dry mass yield ranged from 14,749 to 26,130 kg ha-1. The neutral detergent fiber content ranged from 44.85 to 58.45% and the acid detergent fiber content ranged from 28.28 to 37.06%. The relative feed value of the silage ranged between 100.5 and 138.5. The tester, hybrid Dow8460, was efficient to discriminate the relative performance of the S4 lines in the topcrosses.