Agronomic performance in Paspalum interspecific hybrids subjected to nitrogen application rates or in mixture with temperate legumes

Plicatula is a taxonomic group within of the genus Paspalum that contains interesting species considering their phenotypic diversity for forage traits, and some of these species have been improved through artificial interspecific hybridization. Nitrogen (N) is an important limiting factor to produce biomass. Forage legumes contribute with symbiotic N2 fixation and can increase biomass yield and the nutritive value of the pastures. The objectives of this thesis were: (i) evaluate dry matter yield (DMY), N use efficiency (NUE), nutritive value, cold tolerance and plant persistence in hybrids of Paspalum plicatulum x P. guenoarum subjected to N application rates, (ii) compare biomass yield and nutritive value of the grass–legume system to a grass–N fertilizer system, and (iii) select the best hybrids for new steps within the breeding program. The study was conducted from September 2015 to May 2017. The experimental design was a randomized complete block in split-plot arrangement with three replicates. Treatments were five N rates (0, 60, 120, 240, and 480 kg N ha-1 N), and one grass-legumes mixture (Trifolium repens + Lotus corniculatus) as whole plots, and six genotypes (1020133, 102069, 103084, 103061, P. guenoarum ecotype Azulão and Megathyrsus maximus cv. Aruana used as a control) as subplots. Nitrogen rates of 240 and 480 kg N ha-1 increased Total-DMY, Leaf-DMY, cold tolerance and persistence but decreased NUE. Higher NUE was obtained with N rates between 60 and 120 kg N ha-1. Total-DMY for grass-legume mixture was similar to the N rates of 60 and 120 kg N ha-1. Hybrid 1020133 had Total-DMY similar to Azulão and Aruana, as well as Leaf-DMY greater than Aruana. Hybrid 1020133 showed greater cold tolerance and exhibited greater NUE at 60 kg N ha-1 than the other genotypes. At the N rate of 480 kg N ha-1 increased crude protein (27%) and digestibility (4%) and decreased neutral (6%) and acid (7%) detergent fiber compared to the 0 kg N ha-1. Grass-legume mixture showed greater nutritive value compared to N-fertilized grass. Hybrid 103061 had greater crude protein and digestibility and lower neutral and acid detergent fiber than Azulão and Aruana. Therefore, there is opportunity to increase DMY, NUE, cold tolerance and plant persistence, and improve the nutritive value through genotype selection and N management. In addition, grass-legume mixture showed greater nutritive value than N-fertilized grass and can be an alternative practice to replace to the application of N fertilizer up to the rate of 120 kg N ha-1. Hybrids 1020133 and 103061 should be indicated for new studies, such as seed production and animal performance

Progênies híbridas de grama forquilha : avaliações agronômicas

Paspalum notatum Flüggeis one native forage grasses of southern Brazil. Through intraspecific hybridization, is possible generating progenies with variability for agronomic traits.The objective of this work was to evaluate 24 hybrids and select them for the superior agronomic traits, as well analyze correlations between forage traits that can assist in the selection of genotypes.The hybrids were obtained from crosses among sexual and apomictic clones, and were vegetative propagated in a greenhouse until the transplant to the field. The agronomic traits evaluated were: total green mass (TGM), leaf dry mass (LDM), stem dry mass (SDM), inflorescence dry mass (IDM), dead mass (DeM), total dry mass (TDM),growth habit (GH). Correlations between plant diameter (PD), number of tillers (NT), total dry matter (TDM), plant height (PH), total green matter (TGM), leaf dry matter (LDM), stem dry mass (SDM), number of inflorescences (NINF) and inflorescence dry matter (IDM) were performed using the Pearson correlation coefficient. The hybrids had great variability in all agronomic characteristics measured. Based on the three years of evaluation, hybrids KD9, KF1, KF4, and KD5 produced higher total dry mass than othergenotypes. The hybrid KF4 too had greater LDM; KF1 and KF4 were the colder tolerant. These genotypes were selected for evaluations, such as seed production, fertilizer use efficiency, animal performance, and for new crosses. The high correlation of the total dry mass with the other forage components will be useful for indirect select criteria in bahiagrass improving strategies.Paspalum notatumFlügge é uma gramínea forrageira nativa do sul do Brasil. Hibridizações intraespecíficas geram progênies com variabilidade para características agronômicas. O objetivo deste trabalho foi avaliar 24 híbridos e selecioná-los pelas características agronômicas superiores, bem como analisar correlações entre características forrageiras que possam auxiliar na seleção de genótipos. Os híbridos foram obtidos através dos cruzamentos entre clones sexuais e apomíticos, e foram propagados vegetativamente em casa de vegetação até o transplante para o campo. As características agronômicas avaliadas foram: massa verde total (MVT), massa seca das folhas (MSF), massa seca do caule (MSC), massa seca da inflorescência (MSI), material morta (MM), massa seca total (MST), hábito de crescimento (HC). As correlações entre diâmetro da planta (DP), número de perfilhos (NP), massa seca total (MST), altura da planta (Alt), massa verde total (MVT), massa seca das folhas (MSF), massa seca do caule (MSC), número de inflorescências (NINFL) e massa seca das inflorescências (MSINFL) foram realizados utilizando o coeficiente de correlação de Pearson. Os híbridos tiveram grande variabilidade em todas as características medidas. Em três anos de avaliações, os híbridos KD9, KF1, KF4 e KD5 produziram maior MST; KF4 apresentou maior MSF; KF1 e KF4 foram os mais tolerantes ao frio. Esses genótipos foram selecionados para avaliações de produção de sementes, eficiência no uso de fertilizantes, desempenho animal e para novos ciclos de cruzamentos. A alta correlação da massa seca total com outros componentes da forragem será útil para critérios de seleção indireta em estratégias de melhoramento da grama forquilha

ESTIMATIVA DA CONVERSÃO EM PRODUTO ANIMAL A PARTIR DO USO DE Avena strigosa Schreb. SUBMETIDA A DIFERENTES FONTE S E DOSES DE NITROGÊNIO

The objective of this study was to evaluate the agronomic and economic response of black oat pasture (cv. Embrapa 29 Garoa) submitted to different nitrogen fertilization sources and doses. The experimental design used was a randomized block design, arranged in a factorial scheme: two sources of nitrogen x five fertilization doses x three cuts. Three hundred results obtained demonstrated that black oat crop responds in productive potential from different sources and doses of nitrogen fertilization, impacting differently on the animal product. The choice of fertilization dose within the different sources of nitrogen will depend on the efficiency of nitrogen utilization in fodder production and its conversion to animal production, coupled with the product remuneration and costs involved with pasture implantation. The application of urea as nitrogen source provided greater production of dry matter per cut in black oat culture when compared to ammonium sulfate. The highest efficiencies in the use of nitrogen were obtained by applying 45 kg ha-1 of urea and ammonium sulfate. Black oat culture responds biologically to the nitrogen fertilization dose of 90 kg N ha-1. The applications of 45 kg of N ha-1 in the form of urea and 23 kg ha-1 of ammonium sulfate were economically feasible under the conditions in which the study was carried out.O objetivo do presente estudo foi avaliar a resposta agronômica e econômica da pastagem de aveia preta (cv. Embrapa 29 Garoa) submetida a diferentes fontes e doses de fertilização nitrogenada. O delineamento experimental utilizado foi o de blocos ao acaso, organizado em esquema fatorial: duas fontes de Nitrogênio x cinco doses de fertilização x três cortes. Trezentos resultados obtidos demonstraram que a cultura da aveia preta responde em potencial produtivo a partir de diferentes fontes e doses de fertilização nitrogenada, impactando de maneira diferenciada sobre o produto animal. A escolha da dose de fertilização dentro das distintas fontes de Nitrogênio depende da eficiência de utilização do Nitrogênio em produção de forragem e a sua conversão em produção animal, aliado à remuneração do produto e custos envolvidos com a implantação da pastagem. A aplicação de ureia como fonte de Nitrogênio proporcionou maior produção de matéria seca por corte na cultura de aveia preta quando comparado ao sulfato de amônio. As maiores eficiências de utilização de nitrogênio foram obtidas com a aplicação de 45 kg ha-1 de ureia e sulfato de amônio. A cultura de aveia preta responde biologicamente até a dose de fertilização nitrogenada de 90 kg de N ha-1. As aplicações de 45 kg de N ha-1 na forma de ureia e 23 kg ha-1 de sulfato de amônio foram economicamente viáveis nas condições em que o estudo foi realizado

Agronomic evaluation of Paspalum notatum Flügge under the influence of photoperiod

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

Acúmulo de forragem em híbridos de grama-forquilha em dois ambientes distintos no Sul do Brasil

The native grasslands of southern Brazil have sustained livestock farming for many years; however, decline in pasture areas has led to the loss of genetic diversity of forage species.The development of forage grass cultivars adapted to different environments, will contribute to forming new cultivated pastures or recovering degraded areas.The aim of this study was to assess the herbage accumulation of selected intraspecific hybrid progenies of bahiagrass (P. notatum Flügge) in two different environments(Depressão Central and Campanha region)to estimate their agronomic value. The results indicated variability for the main forage traits studied(leaf dry mass, stem dry mass, inflorescence dry mass, total drymass, leaf: stem ratio,plant height and population density of tillers).All the hybrids producing more forage mass than the ‘Pensacola’ cultivarin the municipality of Eldorado do Sul and the majority also superior in the municipality of São Gabriel.Theproductionof leaves in the forage was correlated withtotal dry mass (84%), suggesting that genotype selection for forage massalso selected for production of leaves. The selected hybrids should be indicated for new steps of assessment within the P. notatumbreeding program.As pastagens nativas do Rio Grande do Sul (sul do Brasil), sustentam a pecuária há muitos anos; no entanto, o declínio em áreas de pastagens tem levado à perda da diversidade genética das espécies forrageiras e o desenvolvimento de cultivares de gramíneas forrageiras adaptadas a diferentes ambientes contribuirá para a formação de novas áresa de pastagens cultivadas ou recuperação de áreas degradadas. O objetivo deste trabalho foi avaliar o acúmulo de forragem de uma progênie híbrida intraespecífica selecionada de grama forquilha (Paspalum notatum Flügge) em dois ambientes distintos (Depressão Central e Campanha)para estimarseu valor agronômico.Os resultados indicaram variabilidade para as principais características forrageiras estudadas(massa seca das folhas, massa seca do caule, massa seca da inflorescência, massa seca total, relação folha:caule, altura daplanta e densidade de perfilhos) com todos os híbridos produzindo mais massa de forragemdo que a cultivar ‘Pensacola’no município de Eldorado do Sul e a maioria também superior no município de São Gabriel. A produção de folhas foi a característica mais correlacionada com a massa seca total(84%), sugerindo que a seleção de genótipos para massa de forragem também selecionou para a produção de folhas.Os híbridos selecionados poderão ser indicados para novas etapas de avaliações dentro do programa de melhoramento de P. notatum

Desempenho forrageiro de híbridos de Paspalum obtidos por meio de cruzamentos interespecíficos

The goal of this study was to assess the variability of Paspalum plicatulum x P. guenoarum interspecific hybrids in terms of agronomic performance and their tolerance to cold conditions, as well as to estimate the correlation of different phenotypic characters associated with forage production. Twenty hybrids plants were used, besides one access P. guenoarum, one of P. plicatulum and the cultivar ‘Pensacola’ (P. notatum). Assessments were performed on individual plants, in a completely randomized design with five repetitions. Paspalum genotypes presented variability in total dry matter, leaf dry mass, leaf: stem ratio, and tolerance to cold. We suggest selection of the hybrids 08Q01 and 08Q44 for new stages within a forage improvement program. Estimates of phenotypic correlation may aid in the selection of genotypes with better agronomic traits.O objetivo deste estudo foi avaliar a variabilidade de híbridos interespecíficos de Paspalum plicatulum x P. guenoarum por meio do desempenho agronômico e tolerância ao frio, bem como estimar as correlações fenotípicas de diferentes caracteres ligados à produção de forragem. Foram utilizados 20 híbridos, um acesso de P. guenoarum, um de P. plicatulum e a cultivar ‘Pensacola’ (P. notatum). As avaliações foram realizadas em plantas individuais, em delineamento completamente casualizado, com cinco repetições. Os genótipos de Paspalum apresentam variabilidade para massa seca total, massa seca de folhas e relação folha: colmo e na tolerância ao frio. É possível selecionar os híbridos 08Q01 e 08Q44 para novas etapas dentro de um programa de melhoramento de forrageiras. As estimativas de correlações fenotípicas podem auxiliar na seleção de genótipos com caracteres agronômicos superiores

Forage potential of native ecotypes of Paspalum notatum and P. guenoarum

The Paspalum genus includes several species that are important for livestock in Rio Grande do Sul, such as P. notatum and P. guenoarum, typical of native pastures of the Pampa biome. The aim of this study was to investigate forage production and chemical composition of four ecotypes of these species in relation to the cv. ‘Pensacola’ (P. notatum). Ecotypes of P. guenoarum (Azulão and Baio) and P. notatum (André da Rocha and Bagual) and the cv. ‘Pensacola’ were evaluated for two years, during which four cuts/year were made. The work was carried out under field conditions at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (30°05’S; 51°39’W), in a completely randomized design. P. guenoarum stood out for higher productivity and greater tolerance to cold; the Azulão ecotype showed more autumn production in relation to the other ecotypes. Crude protein content ranged from 14 (Baio) to 15% (‘Pensacola’); for neutral detergent fiber, the variation was 68 (Azulão) to 71% (‘Pensacola’) and for acid detergent fiber there was a variation of 38 (‘Pensacola’) to 43% (Baio). The data demonstrates the potential of native genotypes for use as cattle feeding in southern Brazil

Multivariate analysis reveals genetic diversity in Paspalum notatum Flügge

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

Genetic parameters, prediction of gains and intraspecific hybrid selection of Paspalum notatum Flügge for forage using REML/BLUP

Genetic improvement of native forage species is a sustainable alternative for maximizing livestock production. Paspalum notatum Flügge is the most important forage grass in the native grasslands of southern Brazil, with substantial potential available for further genetic improvement. The objective of this study was to quantify a range of genetic parameters and predict yield gains in a population of P. notatum intraspecific hybrids. Results indicated intraspecific hybrids of P. notatum had high magnitudes of heritability in the broad and average sense of genotype, plus high selective accuracy and genetic variation for all forage characteristics evaluated. This indicated REML/BLUP can contribute useful information for plant selection in future plant breeding programs. The genetic material studied showed high genetic variability for forage production. Analysis indicated hybrids 336, 332, 437, 132 and male parent ‘30N’ should be included in new crosses to increase the dry matter production of P. notatum. Parents need to be selected from different groups in order to maximize genetic variability and heterosis. In addition, these parents must be included in diallel crosses. The results obtained in this study provide important information for the future breeding of improved P. notatum cultivars for commercialization

Agronomic performance of interspecific Paspalum hybrids under nitrogen fertilization or mixed with legumes

Nitrogen supply and mixtures with legumes affect agronomic performance of pas- tures, 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 repli- cations 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 stud- ies. The agronomic performance of perennial pastures can be improved through N management, and NUE should be a selection criterion in forage breeding