ABSTRACT. The diversity of soils and climate in Brazil imposes the need to evaluate the adaptation of fodder species to soil and climate conditions to guide producers and technicians in choosing the best alternatives for their region. The objective of this study was to evaluate and identify fodder cultivars for pasture and soil cover with tolerance to drought and high production in the sandy soils of southern Bahia, Brazil. The performance of 29 commercial cultivars of perennial and annual tropical forage species was evaluated in six cuts in 2019 and 2020. The green and dry mass yield per cut and the daily dry matter accumulation rate were evaluated considering the periods of water surplus and deficit and the drought tolerance index for each cultivar was estimated. Grass and legume cultivars showed differences in establishment, yield in the water surplus, and in the re-establishment after the water deficit. Based on the values of the drought tolerance index and in the dry mass daily yields before and after the water deficit, the cultivars adapted and indicated for regional continuous grazing were Xaraés, Marandu, Massai, Tanzânia, Paiaguás, and Zuri, in that order. The grasses B. ruziziensis and B. decumbens were indicated for use as cover plants after the harvest due to their high capacity of establishment and short-term production. The annual and perennial legume plants were also indicated for cover, and the combination of cultivars and their potential for straw in direct planting or use in integrated systems still need to be validated.

Abstract High seed yield is a fundamental characteristic of apomictic and sexual hybrids of the genus Urochloa P. Beauv. (syn. Brachiaria (Trin.) Griseb.). It has been suggested that there is an association between polyploidy, the presence of meiotic irregularities, and low seed formation in this genus. The present study aimed to correlate these characteristics in Urochloa polyploid sexual interspecific hybrids in relation to the production of pure seeds. Segregational and non-segregational abnormalities were shown to led to cause the formation of tetrads with micronuclei, microcytes, polyads, and anomalous end products. The correlation between the percentage of meiotic abnormalities and the total production of pure seeds was negative and significant. To our knowledge, this is the first research with sexual polyploid hybrids from Urochloa and is relevant to identify hybrids with less frequent meiotic abnormalities and higher seed yield, with promising female parents for the breeding program.

Abstract Tetraploid Brachiaria ruziziensis genotypes which reproduce sexually are essential for the breeding of other species of the Brachiaria genus which reproduce by apomixis. Aiming at studying the available phenotypic and genetic variability in the breeding population of B. ruziziensis, it was estimated the parameters heritability and genetic and phenotypic correlations between the traits associated with flowering, and the traits responsible for forage yield and nutritional quality. Seventeen traits in 1180 individuals from 59 open pollinated families were studied, and the data were analyzed by mixed model methods. Individuals with sparse flowering presented higher breeding values for total dry matter, yield, and total number of panicles per plant than individuals with early or late flowering. Considering breeding population differences on flowering behavior, on individual narrow sense heritability and on genetic correlations between flowering, agronomic quality and nutritional quality traits have to be considered in intrapopulation breeding and in intrapopulational recurrent selection.

A implantação de sistemas silvipastoris é uma alternativa tecnológica à criação extensiva de gado e, para que haja sucesso, é necessário identificar genótipos de gramíneas forrageiras adaptados à redução de luminosidade. O objetivo deste estudo foi selecionar progênies de P. maximum, tolerantes à redução de luminosidade, para uso em programas de melhoramento, e estudar o controle genético e o desempenho de alguns caracteres associados à tolerância. Foram avaliadas seis progênies de irmãos completos, a sol pleno, a 50% e a 70% de redução da luminosidade, em vasos e sob cortes. Os valores genotípicos (VG) das progênies, em relação à altura das plantas (ALT) e à área foliar específica (AFE), aumentaram com a redução da luminosidade. Para os caracteres acúmulo de massa seca total (MS) e massa verde de lâminas foliares (MSVLF), esses VG foram maiores, com 50%, e intermediários, com 70% de redução da luminosidade. Para o número de perfilhos (PERF) e para o acúmulo de massa seca de raízes (MSR), os VG das progênies diminuíram com a redução de luminosidade. As correlações mais altas e positivas foram obtidas para os caracteres ALT e MSR com AFE e MS; as mais altas e negativas foram entre PERF com AFE e MSR, e ALT com MSVLF. As progênies avaliadas apresentaram maior tolerância a 50% de redução de luminosidade, das quais duas destacaram-se e deverão ser usadas no melhoramento. Evidenciou-se, também, que não é necessária a avaliação de algumas características em todos os níveis de luminosidade. Todos os caracteres apresentaram alta herdabilidade no sentido amplo e alta correlação genotípica entre as progênies, ao longo dos níveis de luminosidade. Há uma diferença genética entre as progênies, quanto à resposta aos diversos níveis de luminosidade, o que permitirá a seleção para a tolerância ao sombreamento

The silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values (GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance

This study was carried out with the objective of estimating the genetic parameters of agronomic traits in Panicum maximum hybrids. Genotypes obtained from the crosses between the sexual plants S10 and S12 and cultivars Tanzania and Mombasa were evaluated. The design was an incomplete blocks design with two replicates (clones) and 33 blocks. Each block was constituted by three lines or plots with nine plants each, which were evaluated in six harvests. All the characters presented low broad sense heritabilities for both the individual harvest and for the mean of harvests and a large difference between the heritability and the individual repeatability coefficient, which may be due to the high permanent environmental variance, mainly for forage dry matter and leaf dry matter. On the other hand, the percentage of leaves also presented low repeatability and permanent environmental variance. The genotypic coefficients of variation were high, except for leaf percentage, but they were also associated with high residual coefficients of variation. Both the broad sense heritabilities per harvest and for the mean of harvests were of moderate magnitude for the agronomic traits evaluated in hybrid individuals of P. maximum. On the other hand, there is variability for selection of important characters such as total and leaf dry matter yields and selection for leaf percentage needs a greater number of harvests to improve selection efficiency. The genotypes presented great variability for Bipolaris maydis leaf spot incidence and this character can be included in the P. maximum breeding program.

Taxonomicamente, Stylosanthes guianensis está dividida em quatro variedades botânicas: var. guianensis, var. pauciflora, var. canescens e var. microcephala. A cultivar 'BRS Bela' é uma das duas cultivares dessa leguminosa forrageira registradas no Brasil e é composta por uma mistura física de sementes de quatro acessos pertencentes a variedades botânicas ainda desconhecidas. O objetivo deste trabalho foi caracterizar a variabilidade genética entre os quatro acessos que compõem esta cultivar e determinar suas inter-relações com acessos de variedades botânicas conhecidas, usando a técnica de polimorfismos de DNA amplificados ao acaso (RAPD). Foram analisados 10 primers decâmeros em 36 acessos, do banco de germoplasma da Embrapa gado de Corte, de S. guianensis: 14 da variedade botânica pauciflora, 11 da var. guianensis, quatro da var. canescens, três da var. microcephala e os quatro acessos da cultivar 'BRS Bela'. As bandas amplificadas foram analisadas como dados binários e uma matriz de similaridade genética foi gerada, usando coeficiente de Jaccard. Com base na dissimilaridade genética, os acessos foram agrupados pelos métodos de ligação média entre grupos (UPGMA) e Tocher. A média de similaridade genética dentro das variedades botânicas foi de 0,72 para var. pauciflora, 0,63 para var. microcephala, 0,62 para var. canescens e 0,46 para var. guianensis. Entre os quatro acessos da cultivar 'BRS Bela', esta média foi de 0,62. Ambos os métodos de agrupamento geraram resultados similares e tenderam a agrupar os acessos da mesma variedade botânica. Os acessos da cultivar 'BRS Bela' foram agrupados com acessos var. guianensis. Os resultados mostram que há variabilidade genética dentro das variedades botânicas de S. guianensis e entre os acessos da cultivar 'BRS Bela' e que existe uma tendência ao agrupamento por variedade botânica.

Taxonomically Stylosanthes guianensis is divided in four botanical varieties: var. guianensis, var. pauciflora, var. canescens and var. microcephala. The 'BRS Bela' cultivar is one of the two cultivars of this forage legume registered on Brazil, it is made up of a physical mixture of seeds of four accessions of unknown botanical varieties. The objective in this research was to characterize the genetic variability among four accessions of the cultivar 'BRS Bela' and to determine its genetic relationship with others accessions of known botanical varieties, using the random amplified polymorphic DNA (RAPD) technique. Ten decamer primers were evaluated in 36 accessions, from the germoplasm bank of Embrapa Beef Cattle, of S. guianensis: 14 of the botanical variety pauciflora, 11 of var. guianensis, four of var. canescens, three of var. microcephala and the four accessions of cultivar 'BRS Bela'. The amplified bands were analyzed as binary data and a matrix of genetic similarity was generated using the coefficient of Jaccard. Genetic dissimilarity data were utilized for clustering the accessions by not weighted pair-group method with arithmetical average (UPGMA) and Tocher methods. The mean genetic similarity within of the botanic varieties was of 0.72 for var. pauciflora, 0.63 for var. microcephala, 0.62 for var. canescens and 0.46 for var. guianensis. Among the four accessions of cultivar 'BRS Bela' this mean was 0.62. Both methods of clustering generated similar results and showed a tendency to cluster the accessions of the same botanical variety. The accessions of cultivar 'BRS Bela' were grouped with accessions of botanical variety guianensis. The results show that there is genetic variability within of the botanical varieties of S. guianensis and among the accessions of the cultivar 'BRS Bela' and that there is a tendency to the clustering by botanical variety.

Os objetivos deste trabalho foram estimar parâmetros genéticos e fenotípicos e realizar a predição de valores genéticos de matrizes e procedências de erva-mate (Ilex paraguariensis). Foram avaliadas 164 progênies de oito procedências, em três locais (Ivaí, PR, Guarapuava, PR e Rio Azul, PR), em relação ao caráter produção de massa foliar (PMF). Os componentes de variância, parâmetros genéticos e valores genéticos foram estimados pelo procedimento REML/BLUP individual (máxima verossimilhança restrita/melhor predição linear não viciada), realizando a análise multivariada para os três locais. Os coeficientes de herdabilidade individual, no sentido restrito, para o caráter PMF foram 0,15 em Ivaí, 0,62 em Guarapuava e 0,23 em Rio Azul. A baixa magnitude desses coeficientes em Ivaí e Rio Azul demanda a utilização de métodos de seleção que utilizem todos os efeitos aleatórios do modelo estatístico. O efeito de procedências foi significativo em Ivaí e Rio Azul, com correlação fenotípica intraclasse de 0,13 em Ivaí e de 0,09 em Rio Azul. As procedências apresentaram correlação genética de 0,95 entre os locais Ivaí e Rio Azul. Nesses locais, as procedências foram mais estáveis nos diferentes ambientes do que as progênies. Foram preditos os valores genéticos em relação a todas as procedências e matrizes em todos os locais quanto ao caráter avaliado. As melhores procedências são Barão de Cotegipe, Quedas do Iguaçu, Cascavel e Ivaí.

The objectives of this paper were to estimate genetic and phenotypic parameters and to predict breeding values for parents and provenances of Ilex paraguariensis. Eight provenances with 164 progenies were evaluated on three sites (Ivaí, PR, Guarapuava, PR and Rio Azul, PR) for the trait leaf weight (LW). All the variance components, parameters and breeding values were obtained by REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) procedure at the individual level, through multivariate analysis involving the three sites. The individual strict sense heritabilities for the trait LW were 0.15 in Ivaí, 0.62 in Guarapuava and 0.23 in Rio Azul, demanding more sophisticated selection methods in Ivaí and Rio Azul. The provenance effect was significant in Ivaí and Rio Azul, with intraclass phenotypic correlation of 0.13 in Ivaí and 0.09 in Rio Azul. The provenances were more stable across sites than progenies with genetic correlation of 0.95 between the sites Ivaí and Rio Azul. Genetic values for all provenances and parents in all sites were predicted for the trait LW. The best provenances are Barão de Cotegipe, Quedas do Iguaçu, Cascavel and Ivaí.