Instability of the expression of morphological and phenological descriptors to environmental variation in white oat.

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Dynamic of dominance, growth and bromatology of Eragrostis plana Nees in secondary vegetation area 1 Dinâmica da dominância, crescimento e bromatologia de Eragrostis plana Nees em área de vegetação secundária

ABSTRACT -The objective of this work was to evaluate the dominance, growth and bromatology of tough lovegrass or 'annoni' grass (Eragrostis plana) in secondary vegetation area. The evaluations were carried out at 23, 45, 64, 86, 111, 132, 153, and 174 days of growth after a mowing. The tough lovegrass was the dominant species on the area, accounting for 76 to 90% of biomass. There was a linear increase for leaf (9.8 kg DM ha -1 day -1 ) and total dry mass (16.9 kg DM ha -1 day -1 ) of the tough lovegrass. During the 111 days of the vegetative stage, the biomass was composed only of leaves, and the flowering started at 132 days. At 174 days, the tough lovegrass accumulated about 4,000 kg DM ha -1 , 650 kg DM ha -1 of which was composed of inflorescences. The growth analysis revealed a specific leaf area of 72 cm 2 g -1 and a maximum leaf area index of 2.1. The leaf area ratio decreased from 72.2 to 43.9 cm² g -1 between the 23 rd and 174 th days. The bromatological analysis showed a high content of neutral detergent fiber (85.3-90.4%) and acid detergent fiber (39.4-42.8%), as well as low crude protein content (3.9-9.9%), indicating the low forage quality of the species. entre o 23º e o 174º dia após o corte. A análise bromatológica mostrou elevados teores de fibra em detergente neutro (85,3-90,4%) e fibra em detergente ácido (39,4-42,8%), e baixo teor de proteína bruta (3,9-9,9%), indicando a baixa qualidade nutricional do capim-annoni. Palavras-chave: Fibra. Índice de área foliar. Massa seca. Proteína bruta. Razão de área foliar

Floral biology of Avena strigosa.

Resumo Biologia floral de cultivares de Avena strigosa. A aveia-preta é uma planta de múltiplos usos no sistema agrícola, contudo programas de melhoramento têm pouco sucesso em obter novos genótipos, não se sabe o motivo exato. Assim sendo, este trabalho teve como objetivo caracterizar e avaliar a morfologia floral e a viabilidade polínica em Avena strigosa. Para isso, duas cultivares de hábito e ciclo contrastantes (IAPAR 61 ? Ibiporã e UPFA 21 ? Moreninha) foram estabelecidas no campo e em vaso no município de Passo Fundo, no norte do estado do Rio Grande do Sul. Foram realizadas avaliações morfológicas na panícula, espiguetas e grãos de pólen das cultivares. Na cv. IAPAR 61 ? Ibiporã foram encontrados os maiores comprimentos de espigueta, ráquila, gluma I, gluma II, pálea, arista e pistilo. Na cv. UPFA 21 ? Moreninha encontrou-se maior comprimento da ráquis, lema e antera apicais e maior densidade de espiguetas na panícula. Em relação à viabilidade polínica, as cultivares não diferem entre si, evidenciando-se que apenas as medidas dos grãos de pólen foram contrastantes. Palavras-chave: Aveia-preta; Morfologia; Viabilidade polínica Abstract Black oat is a plant of multiple uses in the agricultural system, however, without knowing exactly why, breeding programs have had little success in obtaining new genotypes. The goal of this study was to characterize floral morphology and evaluate if there is variability in Avena strigosa in its pollen viability. Thus, two cultivars of contrasting habits and cycles (IAPAR 61 ? Ibiporã and UPFA 21 ? Moreninha) were cultivated in a field and in a vase in the city of Passo Fundo, in the north of the state of Rio Grande do Sul, Brazil. Morphological evaluations were performed on the panicle, spikelets and pollen grains of the cultivars. The largest lengths of spikelet, rachilla, glumes I, glumes II, palea, ridge and pistil were found. in cv. IAPAR 61 ? Ibiporã. Larger length of the rachis, lemma and floret in the apical and greater density of spikelets in the panicle were found in cv. UPFA 21 ? Moreninha. As for pollen viability, the cultivars do not differ from each other, evidencing that only pollen grain measurements were contrasting. Key words: Black oat; Morphology; Pollen viabilit

Genetic dissimilarity in conyza sumatrensis revealed by simple sequence repeat (SSR) markers.

In view of the rapid evolution of Conyza sumatrensis populations resistant to glyphosate, it is necessary to understand the genetic diversity aimed to improve strategies for managing this weed. We investigated the genetic dissimilarity among 15 biotypes of C. sumatrensis from different geographic regions using microsatellite loci. The biotypes, were cultivated in a greenhouse to obtain vegetal material for DNA extraction. Nineteen microsatellite markers (SSR), were developed for C. sumatrensis biotypes. The genetic dissimilarity was estimated by the Jaccard coefficient (JC) and the biotypes grouped by the UPGMA method. The results demonstrated a high dissimilarity (JC = 7.14 to 82.62) of the analyzed material, with the biotypes forming five groups, being one group formed just by the susceptible biotype and in the others grouped by biotypes from distinct locations in the same group The high genetic diversity of C. sumatrensis indicates that the biotypes may show different responses to different management strategies, and that the mechanisms of resistance to herbicides and characteristics of evolution of populations due to adaptability may be some of the factors involved in the genetic variability of the species. Keywords: polymorphism; SSR; tall fleabane; genetic variability RESUMO: Tendo em vista a rápida evolução das populações de Conyza sumatrensis resistentes ao glifosato, é necessário entender a diversidade genética com vistas a melhorar as estratégias de manejo dessa planta daninha. Diante do exposto, objetivou-se com este trabalho investigar a dissimilaridade genética entre 15 biótipos de C. sumatrensis de diferentes regiões geográficas usando marcadores moleculares microssatélites. Os biótipos foram cultivados em casa de vegetação, para obtenção de material vegetal para extração de DNA. Dezenove marcadores microssatélites (SSR) foram desenvolvidos para os biótipos de C. sumatrensis. A dissimilaridade genética foi estimada pelo coeficiente de Jaccard (JC), e os biótipos, agrupados pelo método UPGMA. Os resultados demonstraram alta dissimilaridade (JC = 7,14 a 82,62) do material analisado, com os biótipos formando cinco grupos. A alta diversidade genética de C. sumatrensis indica que os biótipos podem apresentar distintas respostas a diferentes estratégias de manejo e que os mecanismos de resistência a herbicidas podem ser um dos fatores envolvidos na variabilidade genética das espécies. Palavras-chave: polimorfismo; SSR; buva; variabilidade genétic

Reação de Avena spp. à brusone na busca de novas fontes de resistência genética.

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Management of consecutive cuts in the production and quality of wintergreen paspalum seeds

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