Abstract This study aimed to investigate genetic parameters and selection strategies for sugarcane resistance to borer and determine the effects of selection for borer resistance on yield traits. The infestation index by borer (IIB) and yield traits were assessed over 3 years in 35 sugarcane clones planted in four locations in southeastern Brazil. There was no genotype × environment (year or location) interaction for borer resistance. Consequently, selection may be performed at only one location and year or by the mean of clones in several locations and/or years. The borer population affected the genotypic variance for borer resistance but when genotypic variance was significant, heritability was elevated and suitable genetic gain was achieved. Selection for borer resistance reduced the genetic gains for tons of cane per hectare, theoretical recoverable sugar, and tons of sugar per hectare; however, satisfactory selection gains for both borer resistance and yield were achieved using selection index.

ABSTRACT The sugarcane spittlebug, Mahanarva fimbriolata (Walker) (Hemiptera: Cercopidae) is an economically important pest of sugarcane in Brazil. The purpose of this study was to develop and validate a greenhouse methodology to screen large sugarcane populations for resistance to spittlebug Mahanarva fimbriolata. A resistant and a susceptible genotype (H. Kawandang and SP81-3250) were first used to determine adequate days after infestation and levels of infestation (number of nymphs per plant) for comparing the resistance of genotypes. Then, 74 sugarcane genotypes including three susceptible and three resistant controls were screened for resistance. The screening method consists in infesting single-tiller plants supported in a small plant growth unit and assessing the damage by using a 1-5 visual damage score. Our data suggest screening with four to six nymphs per plant and the damage score assessment at least 21 days after infestation. The screening technique was proved reliable as susceptible and resistant controls were placed in their respective resistance category. Three genotypes were classified as resistant while the majority of genotypes were classified as susceptible to spittlebug, indicating the need of breeding for resistance.

Abstract The objective of this study was to evaluate the genotype x environment interaction and to estimate the genetic components of variance and mean using mixed models in early selection of 238 clones of Pinus taeda propagated by somatic embryogenesis. The experiment consisted of a complete blocks design, with 12 replications, with one plant per plot, in four environments, at 1, 3, and 4 years of age. Estimates of heritability and of genetic gains in the evaluated environments showed good prospects for selection of superior genotypes. The effect of genotype x environment interaction was pronounced for all traits investigated. With the simultaneous selection for stability and adaptability, 10% genetic gain was obtained in relation to the mean of the commercial controls. This estimated gain indicates that the somatic embryogenesis technique has been effective in propagation of clones with good productive potential.

RESUMO A broca da cana-de-açúcar Diatraea saccharalis Fabr. (Lepidoptera: Crambidae) é uma das mais importantes pragas da cana-de-açúcar nas Américas. Este estudo foi realizado para investigar múltiplos traços de resistência em oito genótipos de cana-de-açúcar contra D. saccharalis, incluindo cinco cultivares comerciais e três germoplasmas exóticos com potencial para servir de fontes de resistência contra esta praga. A preferência de oviposição foi avaliada por meio de testes de escolha livre e de não-escolha. O desempenho de larvas de estágio inicial que se alimentam das folhas e de larvas de estádio tardio alimentando-se com os colmos também foi avaliado. Houve diferenças entre os genótipos para o número de ovos e posturas no teste de livre escolha, enquanto não foram observadas diferenças no teste de não-escolha. Houve também diferenças na sobrevivência de larvas de estádios iniciais que se alimentam das folhas, índice de lesões e dano no colmo. O genótipo IM76-228 foi o menos preferido para a oviposição e parece que a largura da folha teve alguma influência sobre a preferência dos adultos em vez da intensidade de verde das folhas. IM76-228 e RB867515 provocaram uma mortalidade mais elevada de larvas de estádio inicial alimentando-se dos colmos, enquanto que IM76-228 e RB985523 apresentaram menor dano nas folhas e nos colmos. O genótipo IM76-228 foi o mais resistente a D. saccharalis e pode servir como fonte de genes para resistência em programas de melhoramento de cana-de-açúcar.

ABSTRACT The sugarcane borer Diatraea saccharalis Fabr. (Lepidoptera: Crambidae) is one of the most important pests of sugarcane in the Americas. The purpose of this study was to assess multiple resistance traits in eight sugarcane genotypes against D. saccharalis, including five commercial cultivars and three exotic germplasm with potential to serve as resistance sources against this pest. The oviposition preference was assessed by using both free-choice and non-choice tests. The performance of both early stage larvae feeding on the leaves and late stages larvae feeding within the stalks were also assessed. There were differences among genotypes for number of both eggs and egg cluster in the free-choice test while no differences in non-choice test were observed. There were also differences in survival of early stage larvae feeding on the leaves, foliar injury rating and stalk damage. The genotype IM76-228 was the least preferred for oviposition and it seems that leaf width had some influence on adults’ preference rather than greening of the leaves. IM76-228 and RB867515 causes higher mortality of early stage larvae feeding in the stalks while IM76-228 and RB985523 had lower damage in both leaves and stalks. The genotype IM76-228 was the most resistant to D. saccharalis and could serve as genes sources for resistance in sugarcane breeding programs.

Abstract The objective of this study was to identify superior parents for crosses and the best families to breed new clones of energy cane. The best-performing parents were RB867515, RB93509, KRAKATAU, IM76-228, IM76-229, and US85-1008. The heritability and accuracy values for the traits tons of cane per hectare, fiber, and sucrose content indicate high correlation between the predicted genotypic means and observed values, enabling efficient selection of the best cane energy families. The extensive genetic variation detected and the presence of promising seedlings in the selected segregating population indicate the possibility of using new crosses in some clones and even in future commercial plantings. It was possible to identify the best parents involved in the evaluated crosses, and to select, in the best families, seedlings with a high fiber and good sucrose content, seedlings with high fiber and low sugar content, as well as seedlings with the same fiber and sucrose contents as the current cultivars.

RESUMO. O objetivo desse trabalho foi avaliar a importância dos caracteres agronômicos durante o processo de seleção individual em cana-de-açúcar, além de avaliar o potencial do uso da regressão logística e da árvore de decisão na identificação dos melhores genótipos. Foram avaliados 7.719 seedlings na primeira fase de teste (T1) e 659 clones na segunda fase de teste (T2). Os caracteres número de colmos, saliência da gema e comprimento do entre-nó foram os de maior importância no processo de seleção massal realizado no T1. Vigor da planta, diâmetro de colmo e altura de colmo foram os mais importantes na seleção do T2. Pelo método massal foram selecionados 174 indivíduos no T1 e 113 no T2, enquanto a regressão logística selecionou 153 indivíduos no T1 e 79 no T2. A taxa de erro aparente dos modelos logísticos ajustados para as seleções no T1 e T2 foram de 0,8 e 5,10%, respectivamente. Com o uso da árvore de decisão foram selecionados 67 clones dentre os mais produtivos na fase T2. A elaboração de árvores de decisão apresenta grande aplicabilidade na identificação de clones potenciais nas fases iniciais dos programas de melhoramento genético da cana-de-açúcar.

ABSTRACT. The aim of this study was to evaluate the importance of agronomic traits during the selection of sugarcane (Saccharum spp.), as well as to evaluate the potential for using logistic regression and decision trees to identify the best genotypes. A total of 7,719 seedlings of 128 half-sib families were evaluated during the first test phase (T1), and 659 clones were selected for the second (T2). Logistic regression was applied to both populations. The number of stalks, bud prominence and length of the internode were the most important selection traits in the T1 population. The plant vigor, stalk diameter and stalk height were the most important selection traits in the T2 population. There were 174 individuals selected when using the mass selection method in T1 and 113 individuals in T2, whereas a logistic regression selected 153 individuals in T1 and 79 in T2. The apparent error rates of the logistic models fitted to the selections in T1 and T2 were 0.8 and 5.10%, respectively. By using a decision tree, 67 clones were selected among the most productive ones in phase T2. Therefore, the formulation of decision trees is highly applicable to identifying potential clones during the initial phases of breeding programs.

O objetivo desse trabalho foi avaliar o uso de Redes Neurais Artificiais (RNA) na seleção dentro de famílias de cana-de-açúcar. O melhor modelo de RNA não apresentou erro, sendo capaz de classificar corretamente todos os genótipos, ou seja, a rede tomou a mesma decisão de seleção realizada pelo melhorista durante a aplicação do BLUP individual simulado (BLUPIS), demonstrando a capacidade de aprendizado da RNA a partir das entradas e saídas informadas nas fases de treinamento e validação. Tendo em vista que a seleção via RNA facilita a identificação dos melhores indivíduos e visando desenvolver uma nova estratégia de seleção dentro das melhores famílias, de forma a garantir que os melhores genótipos da população sejam avaliados nas próximas fases do programa de melhoramento, recomendamos, ranquear as famílias via BLUP, selecionar as melhores e realizar a seleção individual via RNA, a partir das informações coletadas em nível individual nas melhores famílias.

The objective of this study was to evaluate Artificial Neural Networks (ANN) applied in an selection process within sugarcane families. The best ANN model produced no mistake, but was able to classify all genotypes correctly, i.e., the network made the same selective choice as the breeder during the simulation individual best linear unbiased predictor (BLUPIS), demonstrating the ability of the ANN to learn from the inputs and outputs provided in the training and validation phases. Since the ANN-based selection facilitates the identification of the best plants and the development of a new selection strategy in the best families, to ensure that the best genotypes of the population are evaluated in the following stages of the breeding program, we recommend to rank families by BLUP, followed by selection of the best families and finally, select the seedlings by ANN, from information at the individual level in the best families.

A eficiência do método BLUP individual simulado (BLUPIS) na seleção de genótipos dentro de famílias de irmãos germanos de cana-de-açúcar no estágio de cana soca, comparada com a seleção utilizando o método BLUP individual, foi avaliada. O número ótimo de genótipos a serem selecionados na melhor família foi estabelecido para as características massa media de colmos, teor de sólidos solúveis totais (BRIX), tonelada de colmos por hectare e tonelada de BRIX por hectare. Foram avaliadas dezessete famílias de irmãos germanos no Centro de Experimentação em Cana-de-açúcar, localizado em Oratórios, MG, Brasil. A metodologia de modelo misto foi utilizada para predizer os efeitos genotípicos de cada família e os valores genotípicos de cada individuo dentro de família. O método BLUPIS mostrou-se eficiente para a seleção individual. O número ótimo de genótipos a serem selecionados na melhor família para obter a maior eficiência do método BLUPIS foi 100, na maioria dos casos.

The aim of this study was to assess the efficiency of the simulated individual BLUP (BLUPIS) method in selecting genotypes within full-sib families of sugarcane in ratoon stage, through comparison with selection using the individual BLUP method. The optimal number of genotypes to be selected in the best families were established for mean stems mass, total soluble solids assay (BRIX), ton of stalks per hectare, and BRIX tons per hectare traits. Seventeen full-sib families were assessed in the Centre for Experimentation in Sugarcane, located in Oratórios, MG, Brazil. Mixed model methodology was used to predict the genotypic effects of each family and the genotypic values of each individual within family. BLUPIS method is efficient for individual selection. The optimal number of genotypes to be selected in the best family for obtaining higher efficiency of the BLUPIS method is 100 in the majority of cases.

O objetivo dessa pesquisa foi avaliar a consistência das análises de trilha em experimentos com cana-de-açúcar, a partir de correlações genéticas, fenotípicas e genotípicas. Foram realizadas 44 análises visando quantificar os efeitos diretos e indiretos da altura de colmos (AC), diâmetro de colmos (DC) e número de colmos (NC) sobre massa de cana (MC). O NC apresentou o maior efeito direto sobre MC em todas as análises com o uso de correlações genéticas e fenotípicas e em 12 análises com uso das correlações genotípicas. O DC apresentou efeito direto elevado sobre MC, superando NC em apenas um experimento, enquanto que AC apresentou menor efeito direto sobre MC na maioria dos experimentos. Os resultados apresentaram maior consistência com o uso de correlações genéticas e fenotípicas. Nos experimentos balanceados as correlações fenotípicas e genéticas apresentaram resultados equivalentes. O NC é o principal determinante das alterações na produção de cana.

The aim of this research was to evaluate the consistency of path analyses in sugarcane experiments based on genetic, phenotypic and genotypic correlations. Forty-four analyses were made with a view toward quantifying the direct and indirect effects of stalk height (SH), stalk diameter (SD) and number of stalks (NS) on sugarcane weight (SW). NS had the greatest direct effect on SW in all the analyses with the use of genetic and phenotypic correlations and in 12 analyses with use of the genotypic correlations. SD had a high direct effect on SW, going beyond NS in only one experiment, while SH had the lowest direct effect on SW in most of the experiments. The results showed greater consistency with the use of genetic and phenotypic correlations. In the balanced experiments, the phenotypic and genetic correlations showed equivalent results. NS is the main determinant of changes in sugarcane production.

O objetivo deste trabalho foi avaliar a faixa de classificação do coeficiente de variação em experimentos com cana de açúcar. Para este estudo, foram consideradas algumas das variáveis mais utilizadas por pesquisadores da cultura. Os dados foram obtidos de extensa revisão bibliográfica em revistas científicas, banco de dados do programa de melhoramento de cana de açúcar da Universidade Federal de Viçosa, dissertações de mestrado, teses de doutorado e relatórios técnicos. Foram propostas faixas de classificação segundo o método de Costa, o qual se baseia no uso da mediana e do pseudo-sigma. As variáveis toneladas de colmos e toneladas de sacarose por hectare apresentaram as maiores faixas de classificação dos coeficientes de variação, enquanto que a variável porcentagem de sacarose apresentou a menor faixa dos coeficientes de classificação. Todas as variáveis apresentaram faixas de classificação específica, evidenciando a necessidade de se considerar, na classificação dos coeficientes de variação, a natureza da variável estudada.

The objective of this paper was to evaluate the range of classification of variation coefficient in experiments with sugarcane. For this study, some of the variables that are mostly used by researchers of the culture were considered. The data was obtained after extensive bibliographical revision from scientific journals, data base from the improvement program of sugarcane from the Federal University of Viçosa, master dissertations, doctorate thesis and technical reports. Classification ranges were proposed according to the Costa method, in which is based the use of a median and pseudo-sigma. The variables tons of stalks per hectare and tons of pol per hectare presented the highest ranges of the classification of the coefficients of variation, while the variable percentage of sucrose presented the lowest range. All of the variables presented specific ranges of classification, showing the need to consider, in the classification of coefficients of variation, the nature of the variable being studied.

Sugarcane (Saccharum sp.) is one of the most important crops in Brazil. The high demand for sugarcane-derived products has stimulated the expansion of sugarcane cultivation in recent years, exploring different environments. The adaptability and the phenotypic stability of sugarcane genotypes in the Minas Gerais state, Brazil, were evaluated based on the additive main effects and multiplicative interaction (AMMI) method. We evaluated 15 genotypes (13 clones and two checks: RB867515 and RB72454) in nine environments. The average of two cuttings for the variable tons of pol per hectare (TPH) measure was used to discriminate genotypes. Besides the check RB867515 (20.44 t ha-1), the genotype RB987935 showed a high average TPH (20.71 t ha-1), general adaptability and phenotypic stability, and should be suitable for cultivation in the target region. The AMMI method allowed for easy visual identification of superior genotypes for each set of environments.

É apresentado o modelo RIDESA de melhoramento de cana-de-açúcar para etanol e sua contribuição científica, tecnológica e na formação de recursos humanos. A RIDESA é a rede interuniversitária para desenvolvimento do setor sucroenergético do Brasil, e foi formada por um convênio de cooperação técnica entre dez Universidades Federais. Apresenta-se o modelo de gestão da rede, o qual envolve, dentre outros aspectos, a parceria público-privada (Universidades-Usinas) para desenvolvimento de cultivares. A RIDESA produziu 59 cultivares desde 1990 e responde, atualmente, por 59% da área total de cultivo com essa planta no Brasil. Nos últimos cinco anos, 286 agrônomos foram treinados nos seus programas de melhoramento nas universidades que compõem a RIDESA. Neste mesmo período, a rede formou 35 mestres, 24 doutores e 7 pós-doutores em pesquisas com a cultura. É apresentada também uma abordagem conceitual sobre os métodos de melhoramento de cana envolvendo a seleção de famílias e a seleção genômica ampla.

In this paper, it is presented RIDESA's model for sugar cane breeding to ethanol, and its scientific, technological and human resources training contributions. RIDESA is an inter-university network for the development of sugar cane industry in Brazil, and was formed by a technical cooperation agreement between ten public universities. The model of network management is presented in this study, which involves, among other things, the public-private partnership (Universities-Mills) for the development of cultivars. RIDESA has produced 59 cultivars since 1990 and is now responsible for 59% of the total area cultivated with this plant in Brazil. In the last five years, 286 agronomists were trained in breeding programs at universities that comprise RIDESA. In this same period, the network formed 35 professors, 24 doctors and 7 post-docs in researches with this crop. It is also presented a conceptual approach on methods of sugar cane breeding involving families and genome-wide selection.

Inúmeras instituições, públicas e privadas, empregam seus melhores esforços para produzir novas cultivares, as quais têm por objetivo garantir a produtividade, reduzir insumos e apresentar características que atendam às expectativas dos consumidores. Algumas universidades brasileiras, em geral originadas de escolas de ensino superior de agricultura, têm contribuído para o melhoramento genético de algumas culturas. Essas universidades também visavam resolver os problemas do setor agropecuário brasileiro, e se tornaram instrumento fundamental para alçar o Brasil como um respeitável ator do agronegócio mundial. Nas últimas décadas, considerando as cinco espécies aqui apresentadas, as Universidades desenvolveram 35 cultivares de aveia branca e tornaram o país autossuficiente nesse grão; desenvolveram 27 cultivares de feijoeiro, 59 de cana-de-açúcar, 62 de soja, 03 de trigo, além de inúmeras e incontáveis cultivares de milho, pois os trabalhos nesta espécie datam muito antes dos registros nacionais de cultivares.

Public and private research institutions employ their best efforts to produce new cultivars, which are intended to ensure productivity, reduce ecological footprint and present characteristics that meet consumer expectations. Some Brazilian universities, which are usually originated from schools of higher education in agriculture, have contributed to the breeding of some crops. These universities also aimed to solve the problems of the Brazilian agricultural sector, and became essential tool to make Brazil an important player in the agribusiness world. In the last decades, regarding the five species presented here, the universities have developed 35 oat cultivars and made the country self-sufficient in this grain; they have also developed cultivars of common beans (27), sugarcane (59), soybean (62), and wheat (03), besides countless corn hybrids, since works in this species date before the establishment of the national cultivar registration system.

The sugarcane cultivar RB937570 is early to medium maturing. It should be grown preferably on medium texture soils with medium to high fertility. In central-southeastern Brazil, RB937570 should be harvested between May and August. It is tolerant to the major economically relevant crop diseases, has a good shoot development after mechanical harvesting and high sucrose yields.

O objetivo deste trabalho foi avaliar a adaptabilidade e estabilidade fenotípica de genótipos de cana-de-açúcar no estado de Minas Gerais. Foram avaliados 15 genótipos em nove ambientes. Os experimentos foram conduzidos em blocos completos casualizados, com três repetições. Para discriminar os genótipos, utilizou-se a variável TPH (toneladas de pol por hectare). Os valores corresponderam à média de dois cortes. Os resultados revelaram que a cultivar testemunha RB867515 apresentou maior adaptabilidade geral e estabilidade fenotípica, seguida pelo genótipo RB987935, que apresentou a maior média e elevada adaptabilidade geral e específica para ambientes favoráveis e desfavoráveis, podendo ser indicada para cultivo comercial.

The objective of this research was to evaluate the adaptability and phenotypic stability of genotypes of sugarcane in the state of Minas Gerais, Brazil. There had been evaluated 15 genotypes in nine environments. The experiments were conducted in a randomized block design with three replications. To discriminate the genotypes the variable TPH (tons of pol per hectare) was used. These values corresponded to the average of two cuts. The results showed that the check RB867515 presented greater general adaptability and phenotypic stability, followed by genotype RB987935, which had the highest average and high general and specific adaptability to favorable and unfavorable environments that may be suitable for commercial cultivation.