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Selection of improved genotypes is important for pasture-based feeding systems in subtropical regions. Our goal was to identify hybrids of Paspalum with enhanced forage yield and cold tolerance across 2 sites [Bagé and Eldorado do Sul (ES)], in Rio Grande do Sul, Brazil. We evaluated 19 P. plicatulum × P. guenoarum hybrids, P. plicatulum genotype 4PT, P. guenoarum cultivars Azulão and Baio and, as Control, Megathyrsus maximus cv. Aruana. At both sites, the experimental design was a completely randomized block with 4 replications. Total dry mass (total-DM), leaf-DM and cold tolerance (ColdT) were recorded. At Bagé, hybrid 102069 produced higher total-DM and leaf-DM than the progenitors and cv. Aruana, while at ES, hybrids 102069 and 10308 produced higher total-DM than 4PT, Azulão and Aruana; hybrid 102069 had higher leaf-DM. At Bagé, 16 hybrids displayed ColdT similar to their progenitors and higher than Aruana, while at ES, 12 hybrids showed ColdT similar to Azulão and Baio and higher than 4PT and Aruana. This study demonstrated that hybrids of Paspalum with superior forage yield to their progenitors and Aruana, and hybrids with higher ColdT than 4PT and Aruana are in existence. The hybridization technique shows potential for producing alternative genotypes with higher forage yield and ColdT for sowing in subtropical regions.

Recent efforts placed on breeding Paspalum species made available novel genetic resources for livestock production systems. Nitrogen (N) is an important factor to increase warm‐season grass nutritive value and production, either as anthropogenic supply or in mixture with legumes. Dry matter yield (DMY) and nutritive value in Paspalum plicatulum Michx. × Paspalum guenoarum Arechav. hybrids in response to different rates of N or in mixture with temperate legumes were evaluated for two years. The experiment was a randomized complete block design in split‐plot arrangement with three replications. Treatments were six N supply systems: 0, 60, 120, 240, 480 kg N/ha and grass–legume mixture [white clover (Trifolium repens L.) + birdsfoot trefoil (Lotus corniculatus L.)] as whole plots, and six genotypes (hybrids: 1020133, 102069, 103084, 103061, P. guenoarum ecotype ‘Azulao’ and Megathyrsus maximus cv. ‘Aruana’ used as controls) as subplots. Higher N rates increased DMY and provided variability among genotypes. In general, grass–legume mixture showed greater crude protein and digestibility, and lower neutral and acid detergent fiber than N fertilized grass (p

The Cynodon spp. collection maintained by United States Department of Agriculture National Plant Germplasm System (USDA-NPGS) has limited information on nutritive value (NV) traits. In this study, crude protein (CP), phosphorous concentration (P), in vitro digestible organic matter (IVDOM), and neutral detergent fiber (NDF) were determined to (i) estimate genetic parameters for NV, (ii) obtain genetic values for the whole population across two harvests, (iii) estimate genotype by harvest interaction (GHI) for NV traits, and (iv) select accessions exhibiting improved NV traits compared to &lsquo, Tifton 85&prime, The experiment was setup as a row-column design with two replicates and augmented representation of controls: Tifton 85, &lsquo, Jiggs&rsquo, and &lsquo, Coastal&rsquo, The whole-population was harvested twice, and data were analyzed using linear mixed models with repeated measures. In addition, a selected population of 15 genotypes were evaluated across 11 harvests to determine the extent of GHI. Genetic parameters revealed the presence of significant genetic variability, indicating potential improvements for NV through breeding. Specifically, P and IVDOM presented large variation, while NDF had lower diversity but some accessions exhibited lower NDF than Tifton 85. Low GHI, except for IVDOM, indicated genotypic stability and potential for selecting improved accessions under fewer harvests. Breeding line 240, PI-316510, and PI-3166536 presented superior NV than Tifton 85.

Nitrogen supply and mixtures with legumes affect agronomic performance of pastures, and both practices can guide breeding decisions in Paspalum hybrids. The goals of this study were: (a) quantify herbage accumulation (HA), leaf accumulation (LA), cold tolerance, and N use efficiency (NUE) in P. plicatulum × P. guenoarum hybrids subjected to N fertilization or grown in a mixture with legumes; (b) compare the grass–legume system to a grass–N fertilizer system; and (c) select the best hybrid for future cultivar releases. A randomized complete block design with three replications and a split‐plot treatment arrangement was used for 2 yr, with five N rates (0, 60, 120, 240, and 480 kg N ha−1) and a grass–legume mixture [grass + white clover (Trifolium repens L.) + birdsfoot trefoil (Lotus corniculatus L.)] as whole plots, and six genotypes as subplots (hybrids: 1020133, 102069, 103084, 103061; and controls: P. guenoarum ‘Azulão’ and Megathyrsus maximus ‘Aruana’). Higher N rates increased HA, LA, and cold tolerance. Higher NUE was obtained between 60 and 120 kg N ha−1. In the grass–legume mixture HA was similar to the rates of 60 and 120 kg N ha−1. Hybrid 1020133 had HA similar to the controls, LA greater than Aruana, and greater cold tolerance and NUE at 60 kg N ha−1 than Azulão and Aruana. Hybrid 1020133 should be selected for further animal performance studies. The agronomic performance of perennial pastures can be improved through N management, and NUE should be a selection criterion in forage breeding.

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.

The rational use of N fertilization is essential to increase the recovery efficiency and crop productivity and decrease the cost of production. The objective of this study was to assess forage yield (TDM), tillers population density (TPD) and N use efficiency (NUE) in six Paspalum notatum Flüggé genotypes in response to N fertilization. The experimental design involved randomized blocks on a subdivided plot design. In 2014-2015 the TDM was higher for the C22 and B26 hybrids (P < 0.0001), which were similar to each other, with an average of 6173 kg DM ha-1 yr-1. In 2015-2016 the TDM of the genotypes ranging from 7053 to 13773 kg DM ha-1 yr-1, for pastures fertilized with 0 and 480 kg N ha-1 yr-1, respectively. An interaction was found between Genotype × N fertilization level (P = 0.0155) for TDM in 2016-2017. In the years 2015-2016 and 2016-2017 the C22 hybrid standed out as the genotype with the highest tiller production in response to N fertilization. In the year 2014-2015 NUE was higher (P = 0.0015) in the N fertilization levels N60, being of 15.5 kg DM kg-1 N. In the years 2015-2016 and 2016-2017 the NUE was higher at fertilization level N120 (P < 0.05), being of 21.1 and 31.5 kg DM kg-1 N, respectively. The C22 hybrid was distinct as the genotype with the highest DM yield and superior tillering characteristics. The N fertilization level of 120 kg N ha-1 yr-1 promoted greater NUE in all P. notatum genotypes

This study aimed to estimate the genetic parameters, genetic correlations, genetic dissimilarity, and predicted gains with the selection of interspecific apomictic Paspalum plicatulum × Paspalum guenoarum hybrids in relation to seed yield traits. Nineteen genotypes that showed increased forage yield in previous studies were planted in a randomized complete block design with ten blocks. Traits evaluated in this study were: number of tillers/plant, number of reproductive tillers/plant, number of racemes/inflorescence, number of seeds/inflorescence, weight of a thousand seeds, and seed yield. Data were analyzed using a mixed model approach. The genotypes evaluated in our study showed improvement potential in relation to high heritability (H a 2 > 0.50 ), high precision (Acgen> 90%), and genetic dissimilarity (forming three groups) for seed yield traits. Seed yield showed high correlation to reproductive tillers that can be used as indirect selection tools for genetic improvement of seed yield.

The aim of this study was to estimate the genetic parameters and predicted gains with selection of interspecific hybrids of Paspalum in relation to seed production traits Data were analyzed in randomized block design, with 23 genotypes arranged into ten blocks, according to the methodology of mixed models by the REML/BLUP procedure. The traits considered in the study were: number of total tillers/plant, number of reproductive tillers/plant, number of racemes/inflorescence, number of seeds/inflorescence, weight of a thousand seeds and seed production. Variability among genotypes, high heritability (>0.50), except total tillers (0.44) and number of racemes (0.36), and high accuracy (>0.90) were identified for all traits. The hybrids 10E5052, 10E4026, 10E507, 10E4025 and 10E40104 are among the top ten because they have high genetic values in three or more traits, indicating that these genotypes should be recommended for direct use in planting or potential parents to be used in new crosses.

This study aimed to determine the variability and expression of the components of seed yield in twenty-three apomictic Paspalum plicatulum × Paspalum lepton hybrids and two male parent plants (P. lepton). We used a randomized block design with genotypes individually arranged into ten blocks. The variables were: number of total tillers/plant, number of vegetative tillers/plant, number of reproductive tillers/plant, percentage of reproductive tillers, number of racemes/inflorescence, number of seeds/inflorescence, weight of a thousand seeds, and seed yield. We assessed genetic variability using multivariate procedures: generalized Mahalanobis distance, Tocher's clustering optimization method, and quantification of the relative contribution of the variables. The quantification of variability, based on the components of seed yield of Paspalum plicatulum × Paspalum lepton hybrids, allows the formation of six groups of genotypes using Tocher's method, with high means for the characteristics studied. Weight of a thousand seeds and number of seeds/inflorescence were the traits that most contributed to the genetic dissimilarity. Genetic crosses involving genotype 10E5052 from group VI and 10E4071 from group V could be undertaken to isolate high yielding segregants, since these genotypes have high seed yielding potential.

The use of genetic divergence as a basis for identifying superior individuals, with greater heterozygosity, is important in view of the difficulty when selecting of dissimilar genotypes exhibiting high average for interest traits. The aim of this study was to evaluate the genetic divergence and the expression of seed production traits in seventeen apomictic Paspalum plicatulum × Paspalum guenoarum hybrids and two male parents (P. guenoarum). A randomized block design was used, with genotypes individually arranged into ten blocks. The following traits were assessed: total number of tillers/plant (TT), reproductive tiller/plant (RT), number of racemes per inflorescence (NRI), reproductive tiller height (RTH), inflorescence rachis length (IRL), number of seeds/inflorescence (NSI), weight of a thousand seeds (WTS) and seed production (SP). Genetic divergence among the genotypes was estimated using the Tocher method and UPGMA clustering, based on the generalized Mahalanobis distance (D2 ii’). The Tocher and UPGMA optimization methods showed high concordance. The traits that most contributed to genetic divergence were RTH (23.59%), IRL (21.63%), WTS (16.67%) and SP (14.23%). The presence of genetic diversity made it possible to identify divergent genotypes and those with high means for the traits studied, allowing the selection of genotypes with significant breeding potential. Repeated cross-breeding of female superior plants with the genotypes Azulão and H20 can result in a high heterosis effect on seed production characteristics. RESUMO A utilização da divergência genética como base para a identificação de indivíduos superiores, com maior heterozigose, é importante diante da dificuldade de escolha de genótipos dissimilares, que apresentem média elevada para as características de interesse. O objetivo deste trabalho foi avaliar a divergência genética e a expressão dos caracteres da produção de sementes de dezessete híbridos apomíticos de Paspalum plicatulum × Paspalum guenoarum e dois genitores masculinos (P. guenoarum). O delineamento experimental utilizado foi o de blocos casualizados, com os genótipos arranjados individualmente em dez blocos. Foram avaliadas as seguintes características: total de perfilhos/planta (TP), perfilhos reprodutivos/planta (PR), número de racemos/inflorescência (NRI), altura dos perfilhos reprodutivos (APR), comprimento de inflorescência (CI), número de sementes/inflorescência (NSI), peso de mil sementes (PMS) e produção de sementes (PS). A divergência genética entre os genótipos foi estimada pelos métodos de agrupamento de Tocher e UPGMA, com emprego da distância generalizada de Mahalanobis (D2 ii’). Os métodos de otimização de Tocher e UPGMA foram concordantes entre si. As características APR (23,59%), CI (21,63%), PMS (16,67%) e PS (14,23%) foram as que mais contribuíram para a divergência genética. A presença de variabilidade genética permitiu a identificação de genótipos divergentes e com médias elevadas para os caracteres estudados, o que possibilita selecionar genótipos com elevado potencial para fins de melhoramento genético. O cruzamento repetido de plantas sexuais superiores com os genótipos Azulão e H20 pode proporcionar efeito heterótico elevado nos caracteres da produção de sementes.

The objective of this study was to evaluate the practice of consecutive cuts in the production and quality of Paspalum guenoarum seeds of the "Azulão" ecotype. The experimental design used was in completely randomized blocks with four replications. The treatment included three cuts in succession: zero cut, one cut, two cuts, and three cuts. The variables were: number of total tillers/plant; number of vegetative tillers/plant; number of reproductive tillers/plant; percentage of reproductive tillers; number of racemes/inflorescence; weight of thousand seeds; number of seeds/inflorescence; seed production; forage dry matter; water content of seeds; germination; first germination count; and germination speed index. The largest seed production was obtained with zero cut (850.3, first year and 719.4 kg/ha-1, second year) and one cut (794.4, first year and 627.3 kg/ha-1, second year) with no statistical difference between them. The largest germination percentage was seen with the application of zero (71.0%, first year and 79.3%, second year) and one cut (69.3%, first year and 75.0%, second year). There was a decrease in the production and quality of the seeds of the second cut, especially during the first year of evaluation. The total tillers, the percentage of tillers that went through the reproductive stage, and the number of reproductive tillers are the variables that are most highly correlated with seed production.

O objetivo deste trabalho foi avaliar o teste de envelhecimento acelerado, com e sem solução de NaCl, na predição da qualidade fisiológica e sanitária de sementes de cornichão (Lotus corniculatus L.). O delineamento experimental foi o inteiramente casualizado, foram utilizados dez lotes de sementes submetidos a três períodos de condicionamento (24, 48 e 72 h, a 41 ºC). A caracterização fisiológica dos lotes consistiu na determinação do teor de água (antes e depois do envelhecimento acelerado), germinação, primeira contagem de germinação, índice de velocidade de germinação, emergência de plântulas e teste de sanidade de sementes. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Scott-Knott, a 5% de probabilidade. As metodologias de envelhecimento acelerado com solução salina e solução saturada de NaCl, condicionadas por 48 h, correlacionaram-se com o teste de emergência de plântulas (0,52 e 0,69, respectivamente), permitindo a predição da qualidade fisiológica de sementes de cornichão. A utilização de solução saturada durante 48 h diminui a incidência de fungos. O método tradicional não é recomendado por proporcionar variação do teor de água entre as amostras, superior ao tolerável. The objective of this study was to evaluate the accelerated aging test, with and without NaCl solution, predicting the physiological health and quality of birdsfoot trefoil (Lotus corniculatus L.) seed. The experimental design was completely randomized. Ten seed lots were submitted to three conditioning periods (24, 48 and 72 h at 41 ºC). The physiological characterization of the lots was the determination of water content (before and after accelerated aging), germination, first germination count, germination speed index, seedling emergence and seed health test. The data were submitted to variance analyze and the averages were compared by the Scott-Knott test, at 5% probability. The accelerated aging methodologies with saline solution and saturated NaCl solution, conditioned for 48 h, were correlated with seedling emergence test (0.52 and 0.69, respectively), allowing the prediction of physiological quality of birdsfoot trefoil seeds. The use of saturated solution for 48 h decreases incidence of fungi. The traditional method is not suitable because it provides water content variation between samples above the tolerable.