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The quality of forage production is a prerequisite to raising livestock. Therefore, income losses in this activity, primarily cattle raising, can result in the impossibility of economic activity. Through the qualitative and quantitative anatomical study of Urochloa hybrida cv. Mulato II and U. brizantha cv. Marandu, we searched for descriptions and compared changes in the individual vegetative body from populations with death syndrome pastures (DPS). Specimens were collected at different physiological stages from farms in northern Mato Grosso. After collection, the individuals were fixed in FAA 50 and stored in 70% alcohol. Histological slides were prepared from the middle third of the sections of roots, rhizomes, and leaves, and the proportions and characteristics of tissues were evaluated in healthy, intermediate, and advanced stages of DPS. Changes were compared between cultivars. With the advancement of the syndrome, the following changes were observed: a more marked decrease in the length of roots in U. hybrida; disorganization of the cortical region of the roots and rhizome cultivars; fungal hyphae in roots and aerenchyma formation in U. hybrida; a decrease in sclerenchyma fiber proportions in roots and leaves; sclerification of the epidermis of U. brizantha rhizomes; and an increase in pericyclic fibers in U. hybrida. Furthermore, there was a decrease in the volume of epidermal cells of the abaxial face of the leaves of both cultivars, with a greater reduction in U. hybrida; a gradual decrease in thickness in the midrib of leaves similar to leaf mesophyll; conduction system obstructions; partial or total cell lysis in roots and rhizomes affected by the syndrome. Obstructions in sieve tube element and companion cells, and sometimes obstruction in xylem vessel elements. The evolution of DPS in cultivars was similar, but there were variations, arising probably from the physiological response to stress, such as aerenchyma formation in the root and increased pericycle in the rhizome of U. hybrida.Keywords: forage, plant anatomy, fungal hyphae. Síndrome da morte das pastagens: Alterações teciduais em Urochloa hybrida cv. Mulato II e Urochloa brizantha cv. Marandu ResumoA produção de forragem de qualidade é um pressuposto indispensável à atividade pecuária moderna. Dessa forma, perdas de rendimento nesta atividade preliminar à criação bovina, podem inviabilizar esta atividade econômica. Através de estudos anatômicos qualitativos e quantitativos em Urochloa hybrida cv. Mulato II e U. brizantha cv. Marandu buscou-se descrever e comparar as alterações do corpo vegetativo de indivíduos de populações que apresentam síndrome da morte das pastagens (SMP). Foram coletados indivíduos em estádios morfológicos distintos em propriedades rurais no norte de Mato Grosso, Amazônia Meridional. Após a coleta, os indivíduos foram fixados em FAA 50 e armazenados em álcool 70%. Lâminas histológicas foram confeccionadas a partir de secções do terço médio de raízes, rizomas e folhas, onde foram avaliadas as características e p...

The aim of this study was to compare vitroplants Catasetum x apolloi grown under natural light and artificial light and different concentrations of potassium silicate, providing data on the anatomical differentiation that aids the acclimatization process of this species. Plants from in vitro seeding were used; 5 protocorms of approximately 0.5 cm were inoculated into vials with a capacity of 500 mL containing 100 mL of alternative culture medium plus potassium silicate (0.0, 0.5; 1.0 mL L -1 ), pH adjusted to 5.5 ± 0.5 and gelated with 4GL -1 agar before the autoclaving process. Cultures were maintained under natural light (TNE) and artificial light (TAE) for 90 days, and micromorphometric analysis was performed for polar and equatorial diameter, density and stomatal index, blade thickness in the central rib, and secondary veins. Applications in K 2 SiO 4 alternative medium provided the following: elongation of the hypodermis, thicker mesophyll, and more prominent midrib; elipptical guard cells; formation of epistomatal chamber; and lower stomatal density and stomatal with lower equatorial and polar diameters. The conditions that favored the acclimatization were lower light intensities and lower potassium silicate doses.Keywords: leaf anatomy, light, orchids, plants vitro. Anatomia e análise micromorfométrica foliar de Catasetum x apolloi Benelli & Grade com adição de silicato de potássio em diferentes fontes de luzResumo O objetivo desse trabalho foi comparar vitroplantas de Catasetum x apolloi cultivadas sob luz natural e luz artificial e diferentes concentrações de silicato de potássio, fornecendo dados sobre diferenciação anatômica que auxiliem no processo de aclimatação dessa espécie. Utilizou-se plantas provenientes da semeadura in vitro, 5 protocormos de aproximadamente 0,5 cm foram inoculados em frascos com capacidade para 500 mL contendo 100 mL de meio de cultura alternativo, acrescido de silicato de potássio (0,0; 0,5; 1,0 mL L -1 ), pH ajustado para 5,5 ±0,5 e gelificado com 4gL -1 de ágar antes do processo de autoclavagem. As culturas foram mantidas sob luz natural (TAA) e luz artificial (TAN) por 90 dias, e feitas análises micromorfométricas (diâmetro polar e equatorial, densidade e índice estomático, espessura do limbo na nervura central e nervuras secundárias). As aplicações de K 2 SiO 4 em meio alternativo, propiciaram: alongamento da hipoderme; mesofilo mais espesso e nervura central mais proeminente; células guardas elípticas; formação de câmaras supraestomáticas; menor densidade estomática e estômatos com menores diâmetros equatorial e polar. As condições que podem favorecer a aclimatação são menores intensidades de luz e menores doses de silicato de potássio.Palavras-chave: anatomia foliar, luminosidade, orquídeas, vitroplantas.

Roots and leaves of Panicum maximum Tanzânia, Mombaça and Massai; Urochloa brizantha Piatã, Marandu and Xaraés; Urochloa humidicola Llanero; Urochloa ruziziensis Ruzizienses; Urochloa hybrida Mulato II and Cynodon nlemfuensis Estrela-roxa were analyzed, seeking to identify characters for better adaptation to the environment that may interfere with digestibility of tissue from the point of view of the rumen in cattle. Were planted ten cultivars in a completely randomized blocks with three repetitions. Was collected vegetative material, which histological slides were prepared from middle third of the sections of roots and leaves. Were observed differences (p>0.05) in the roots: higher volume of epidermal cells (28.62 µm) and overall diameter (1926.41 µm) of Llanero; thicker vascular cylinder (975.09 µm) and more protoxylem (42.25) in Estrela-roxa and occurrence of aerenchyma in cultivars Piatã, Mulato II, Xaraés, Massai, Llanero and Estrela-roxa; Were found higher proportions of bulliform cells in the leaves (121.07 µm) and thicker leaf mesophyll in U. humidicola Llanero (263.63 µm); higher proportion of sclerenchyma fibers in Xaraés and Marandu; lower results for amount of fibers in P. maximum Massai. We conclude that the cultivars Estrela-roxa, Llanero and Massai have greater adaptability to the environment and better nutritional quality. Keywords