Abstract The Paspalum genus has potential for further genetic improvement because of its adaptability to different ecosystems and production of high yields for grazing livestock. We estimate the genetic parameters of 195 intraspecific P. notatum hybrids using Restricted Maximum Likelihood (REML), followed by selection based on Best Linear Unbiased Prediction (BLUP) through multivariate analysis. The intraspecific hybrids studied showed considerable genetic variability in the evaluated forage traits, displaying their potential for progression in subsequent stages of the genetic improvement program. Notably, plant height emerged as an important trait for indirect selection to enhance forage production. The use of the REML/BLUP procedure proves to be a robust tool for data analysis, particularly for perennial species. Furthermore, multivariate analysis based on BLUPs should be used in the selection process within breeding programs. Based on the BLUP values, hybrids D3, D16, C17, C2 and B17 were identified as superior for forage production, and they hold promise for future breeding programs for future breeding initiatives aimed at direct selection to improve yield.

ABSTRACT The objective of this study was to verify the repeatability of the expression of forage characters in intraspecific hybrids of Paspalum notatum Flügge to aid early selection. Across five harvests, plant height, tiller population density, leaf dry matter, stem dry matter, inflorescence dry matter, total dry matter, and growth habit were quantified for five parents, 189 hybrids, and a commercially available cultivar as a control (n = 195). Analysis of variance, principal components analysis, and structural analysis methods were used to determine the repeatability coefficients. The repeatability coefficients ( ρ ^) for all evaluated characteristics generated by the different methods were between 0.05 (ANOVA II) and 0.95 (PCACov). For most of the characteristics studied, repeatability coefficients and determination coefficients were considered high. The repeatability coefficients estimates obtained for the eight characteristics evaluated with the ANOVA I and II methods were almost always lower than those obtained by PCA and structural analysis methods. Based on the covariance matrix, the principal component method generated higher estimates than those produced by ANOVA or structural analysis. Assuming a minimum 80% reliability to verify the relative superiority of the hybrids across all assessed traits, the five harvests proved adequate for selecting the optimal plant materials to advance to the next phase of the breeding program. However, reliable early selection for leaf dry matter, leaf:stem ratio, and total dry matter required a minimum of two harvests. The genetic parameters (h2 and CVg) showed a favorable scenario for direct selection to increase forage production.

RESUMO: Andropogon lateralis Nees é uma gramínea nativa do sul do Brasil e uma das espécies mais frequentes na flora dos campos nativos da região. Possui ampla distribuição e alto grau de plasticidade fenotípica, tornando-o adaptável as condições edafoclimáticas e a práticas de desfolha. Este estudo teve como objetivo avaliar a dissimilaridade entre doze ecótipos de A. lateralis N., coletados em diferentes regiões do Rio Grande do Sul, submetidos a duas frequências de desfolha e três alturas de corte. No período de setembro a fevereiro, os ecótipos foram avaliados quanto à produção de matéria seca total, de lâminas foliares e de colmo. Além disso, foram medidos o número de perfilhos totais, vegetativos e reprodutivos e a altura das plantas. Essas características são importantes para a seleção de genótipos superiores em termos de variabilidade genética e produção de forragem. A matéria seca total e a matéria seca foliar são características com importância agronômica e apresentaram a maior correlação (r = 0,77), possibilitando uma seleção indireta para uma dessas características. A seleção natural das plantas resultou em características estruturais, morfológicas e produtivas distintas com uma heterogeneidade que permite a seleção e agrupamento de acordo com as características, ecótipos com características agronômicas superiores podem ser incluídos em programas de melhoramento.

ABSTRACT: Andropogon lateralis Nees is a native grass of southern Brazil and is one of the most frequent specie found in native grasslands. The species is widely distributed and has a high degree of phenotypic plasticity, which makes it highly adaptable to different edaphoclimatic conditions and management. This study aimed to evaluate the behavior of twelve ecotypes of A. lateralis, collected in different regions of the state of Rio Grande do Sul and cut to three different heights and subjected to two different defoliation frequencies. From September to February, the ecotypes were evaluated for total dry matter, leaf and stem yields. In addition, total, vegetative and reproductive tillers and plant height were measured. These characteristics are important for the selection of superior genotypes in terms of genetic variability and forage production. Total dry matter and leaf dry matter are characteristics with agronomic importance and they showed the highest correlation (r = 0.77), enabling an indirect selection for one of these characteristics. The natural selection of plants resulted in distinct structural, morphological and productive characteristics with heterogeneity that allows the selection and grouping according to the characteristics, ecotypes with superior agronomic characteristics can be included in breeding programs.

ABSTRACT The objective of this research was to identify the existence of root exudation of organic acid in Lotus corniculatus germplasms subjected to toxic aluminum (Al) levels and investigate the effect of this mechanism on the Al content in the root tissue and in morphological parameters of plant development. Two experiments were performed in nutrient solution to evaluate the Al accumulation and exudation of organic acids, using cultivars INIA Draco and São Gabriel and genotypes UFRGS and UF-T2. The plants were cultivated in Al-free solution, which was applied on the 45th day in half of the pots of each genotype. Root exudation was highly correlated with the reduced accumulation of Al in the root tissue (r2 = 0.75 at 72 h). Genotype UF-T2, selected for Al tolerance, extruded 80% more oxalic acid in the presence of Al compared with the other germplasms, indicating that this mechanism is involved with Al tolerance in L. corniculatus. This experiment showed strong evidence that L. corniculatus exhibits Type I tolerance, in which anionic channels are rapidly activated by Al exposure. Exudation of oxalic acid is likely a crucial mechanism that allows the maintenance of L. corniculatus growth when exposed to toxic Al conditions, and this characteristic should be used to identify tolerant genotypes in the future.

ABSTRACT The objective of this work was to describe morphology and grouping of Paspalum notatum accessions, based on multicategorical data which discards the redundant variables for quantification of genetic diversity. We also tested the hypothesis that geographical distance was correlated with morphological divergence. In our study, multivariate analyzes successfully demonstrated the geographic and morphological variability of the P. notatum accessions characterized. Many of these evaluated accessions can be included in future genetic improvement programs. Based on two methodologies for discarding variables, it was possible to identify the potentially important morphological characteristics from genetic diversity studies and characterize new accessions aimed at improving forage and seed production. The methodologies used to discard variables are biometric tools that can be used successfully in future plant breeding programs, especially when a large number of traits and accessions are being evaluated. Although significant, geographic distance had a low association with morphological traits. This indicated the need to use other characteristics, such as forage and seed yield, in addition to molecular analysis. Our analyzes showed genetic variability in P. notatum for all the characteristics studied.

ABSTRACT The objective of this work was to determine Paspalum notatum genotypes appropriate for the establishment of mixtures with temperate legumes and compare the productivity of mixtures with mineral-fertilized systems along two years. Four hybrids of P. notatum, ecotype Bagual and cv. Pensacola, were either subjected to mixtures with white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus) or fertilized with 0, 60, 120, 240, and 480 kg N ha−1 year−1. P. notatum leaf blades and stems and herbage accumulation denoted a management × year interaction. Herbage accumulation varied between the mixtures and fertilized systems in first year, while in the second year, herbage accumulation of mixed systems employing the B26, B43, C22, C9, and Bagual genotypes were similar to that of systems fertilized with 120 and 240 kg N ha−1. Hybrids B26 and C9 and ecotype Bagual, once made available to producers, could be indicated for mixtures with temperate legumes because they are superior to cv. Pensacola. Herbage accumulation in mixtures involving white clover plus birdsfoot trefoil and P. notatum genotypes is similar to that of mineral nitrogen-fertilized systems with 240 kg N ha−1, emphasizing the viability of mixed between these species.

ABSTRACT The objective of this study was to evaluate 94 Paspalum notatum genotypes over two growing seasons to estimate genetic dissimilarity through agronomic traits and the distance between genotypes. This information is used to create an ideotype from the best averages obtained for the set of characteristics evaluated. Seven apomitic, three sexual, and 81 hybrid genotypes were compared with native genotypes “André da Rocha”, “Bagual”, and cultivar “Pensacola” as controls. There is genetic variability in P. notatum for the studied characteristics, and distinct genotypes with superior characteristics can be used in new combinations between apomictic and sexual plants to obtain hybrids. The characters with the greatest relative contribution to the dissimilarity between the genotypes were tiller density, stem dry mass, and leaf dry mass yield. Thus, these characteristics are suitable criteria to infer genetic distance studies in P. notatum . The selection index based on the ideotype is an auxiliary tool in the breeding process. The ideotype must be based on characteristics of interest according to the objective of the breeding program, as well as on the breeder’s prior knowledge in relation to culture.

Abstract Paspalum notatum is an important forage native to Southern Brazil and one of the most promising fodder species in terms of productivity, quality, resistance and growth speed. The objective of this study was to evaluate the reproductive mode and fertility of hybrid progenies resulting from artificial crosses among artificially duplicated sexual plants, selected intraspecific hybrids of the UFRGS breeding program and apomictic ecotypes of the species. The resulting F1 progenies were represented by 24 plants with high pollen viability (varying from 82.15 to 99.67%) and 1.2:1 segregation for the sexual: apomictic reproduction mode, indicating predominantly sexual hybrids, due to distorted segregation. In the apomictic plants, most chromosomes paired as bivalents in diakinesis. Since the low presence of abnormalities observed in the meiotic chromosome pairing and the high pollen viability of the hybrids, all plants were confirmed as promising parents for future crosses.

ABSTRACT: For many decades, animal production in southern Brazil has been based on native forage grasses. Paspalum notatum Flügge (bahiagrass) is one of the most frequently used native grass in southern Brazil. The native germplasm of P. notatum is tetraploid and displays apomictic reproduction; hence, chromosome doubling of sexual diploid accessions is required to facilitate hybridization. The main goal of this study was to evaluate forage production and other agronomical evaluation of P. notatum intraspecific hybrids in order to obtain new varieties that could be registered and/or protected and launched as new cultivars in the future. Three tetraploid sexual genotypes were crossed with the ecotypes Bagual and André da Rocha. Biomass production (leaf, stem, and inflorescence fractions), plant growth habit, plant height, number of tillers, and frost damage were evaluated in the resulting hybrids. The general combining ability (GCA) and specific combining ability (SCA) were calculated for the six families generated. We evaluated 196 hybrids and the most productive yielded 42 % more total dry mass than the most productive parent (ecotype Bagual), and Bagual production was seven-fold higher than that of cultivar ‘Pensacola’. The highest GCA values were observed for Bagual and Q4205. No correlation was observed between leaf coloration and the frost effect or regrowth in the following winter. Similarly, no correlation between plant growth habit and dry mass production was observed. The reproduction mode of the most productive hybrids are currently being analyzed in larger plots to identify apomictic and sexual genotypes for future registration and protection.

ABSTRACT The objective of this study was to assess the genetic diversity among accessions of Paspalum notatum based on morphological marker traits and identify those morphological traits that contribute most to the variability among accessions. Fifty-three accessions were evaluated for the following traits: length, width, color, and pubescence of sheath; length, width, insertion angle, color of midrib, and pubescence of leaves; number, length, and angle of racemes; length of flowering stems; and plant growth habit (erect or prostrate). Multivariate analysis of the quantitative morphological data based on the Mahalanobis distance and UPGMA method grouped the accessions into 19 heterogeneous clusters. The relative contribution of each trait to cluster formation was obtained using the Singh method. Qualitative morphological traits were used to construct a dendrogram based on Jaccard's similarity, generating 13 clusters. Based on the morphological traits investigated, there is high genetic variation among accessions of P. notatum, demonstrating that these accessions have a good potential for a breeding program. Length of racemes, width of sheath, length of flowering stems, and length of leaves were found to contribute most to the variability among accessions. A number of traits contributed to a lesser degree. The set of characters used are representative of the vast phenotypic plasticity observed in P. notatum, a diversity which is likely to be related to the species apomictic form of reproduction and the origin of the accessions.

ABSTRACT The aim of this study was to determine the mode of reproduction of a hybrid progeny derived from intraspecific crosses of Paspalum notatum through cytoembryological analysis and use of RAPD (random amplification of polymorphic DNA) molecular markers. Cytoembryological analysis allowed identification of the mode of reproduction of 28 plants that were selected after agronomic productivity evaluations. Of these, 19 had embryo sac morphology compatible with an apomictic mode of reproduction and nine had embryo sac morphology compatible with a sexual mode of reproduction. Meanwhile, molecular marker analysis for 194 individuals showed 54 sexual and 140 apomictic plants; of the 28 plants analyzed by the two methods, ten results (35.7%) were in disagreement. In this paper, through cytoembryological analyses, a ratio of 1:2.1 of sexual to apomictic plants was found. The BCU 243 marker showed a stable pattern of amplification, but some results differed with cytoembryological analyses, demonstrating that these analyses are more reliable when determining the mode of sexual reproduction for the plants of P. notatum. Apomictic plants characterized in this work can be tested in the field to check their agronomic value and registration as plant varieties, while the sexual plants can be used as potential parents in future crosses.

ABSTRACT The objective of this study was to evaluate the influence of photoperiod on the forage yield by ecotypes and intraspecific hybrids of P. notatum. Tetraploid ecotypes from the United States Department of Agriculture and the National University of the Northeast in Argentina, in addition to six intraspecific hybrids, totaling 19 ecotypes, were assessed. The materials evaluated were subjected to an extended photoperiod (14 h of light) and natural photoperiod from July 2011 to October 2012. The experimental design was a completely randomized factorial scheme of 19 × 2 (ecotypes × photoperiod) consisting of five replicates. The materials were influenced differentially by the variation in photoperiod, with one group showing high sensitivity, whereas another, smaller group, was insensitive to this factor. The use of materials with differentiated responses to photoperiod in different climatic regions can be an important tool to increase forage yield of Paspalum notatum.

Abstract The objective of this study was to identify polyploid plants from citrus rootstocks and to evaluate the influence of the genetic constitution and of the environment on the frequency of chromosome duplication. Populations obtained from rootstock seeds of Trifoliata [Poncirus trifoliate (L.) Raf], citrumelo 'Swingle' [C. paradise Macf. × P. trifoliate], citrange 'Troyer' [C. sinensis (L.) Osb. x P. trifoliate] and citranges Fepagro 'C13', 'C37' and 'C41' [C. sinensis (L.) Osb. cv. Pêra x P. trifoliata] were evaluated under field and greenhouse conditions. Flow cytometry analysis of 415 field plants and 435 greenhouse plants identified seven (1.69%) and 29 (6.67%) tetraploids, respectively. Differences in the number of tetraploid plants among genotypes and locations were observed in field progenies of 'C 37' (2.12%) and 'C 13' (2.04%) and in greenhouse progenies of 'C 13' (15.52%) and 'C 37' (6%). The frequency of autotetraploidization events in citrus rootstocks is common and appears to be associated to genetic constitution and environmental conditions.

The objective of this study was to analyze the adaptability and the stability in apomictic genotypes of the genus Paspalumacross the main characters of forage interest evaluated in different years and locations. The experiment was conducted in the years 2010 and 2011 in the municipalities of Eldorado do Sul and Augusto Pestana, RS, Brazil, in a randomized complete block design with three replications. Analyses of adaptability and stability were calculated by the Traditional and the Eberhart and Russel method. The genotypes of P. guenoarumBaio anda Azulão shows high biomass production but adapted to favorable environments and reduced stability. The genotypes of P. lepton28C show the total dry mass specific adaptability to unfavorable environment and in the dry leaf adaptability with stability

Paspalum notatum é uma das mais importantes espécies das pastagens nativas do Sul do Brasil, que é a principal fonte forrageira para a pecuária. Os ecótipos nativos são tetraploides e de reprodução apomítica, o que impede o registro e a proteção de cultivares. Porém, uma variedade cultivada, Paspalum notatum var. saurae (cultivar Pensacola) é diplóide e sexual. O objetivo deste trabalho foi de poliploidizar artificialmente plantas de cv Pensacola, para serem utilizadas como genitores femininos em cruzamentos com genitores masculinos tetraploides e apomíticos. Plântulas e sementes foram tratadas por imersão com soluções de colchicina por tempo de exposição variável. Três plantas confirmaram número cromossômico tetraploide. As plantas polyploides obtidas serão avaliadas quanto ao modo de reprodução; se confirmarem ser sexuais, serão utilizadas nos esquemas de cruzamentos com plantas apomíticas nativas para obtenção de novos híbridos intraespecíficos.

Paspalum notatum is one of the most important native grassland species of southern Brazil, and the main forage source for livestock. The native ecotypes are tetraploid and have apomictic reproduction, which prevents the registration and protection of plant varieties. However, the cultivated variety Paspalum notatum var. saurae (cultivar Pensacola) is diploid and sexual. The objective of this study was to artificially produce polyploid cv. Pensacola plants, to be used as female parents in crosses with male tetraploid and apomictic parents. Seedlings and seeds were immersed in colchicine solutions for different periods. A tetraploid chromosome number was confirmed in three plants. The reproduction mode of the resulting polyploid plants will be assessed; if confirmed to be sexual, they can be used in crosses with native apomictic plants to breed new intraspecific hybrids.