Leaf anatomy of 'Marandu' grass cultivated in plant arrangements in agrosilvopastoral systems

The objective of this work was to evaluate the effects of different arrangements of eucalyptus plants on the morphoanatomical characteristics of leaf blades of 'Marandu' grass [(Urochloa brizantha (Syn. Brachiaria brizantha)] plants cultivated in agrosilvopastoral systems. The experiment was set in field conditions in a randomized complete block design with four replicates, in which the plots were represented by planting spacings of eucalyptus (12x2 and 12x4 m), and the subplots, by the distance between 'Marandu' grass and eucalyptus rows (6, 4, and 2 m). A control was added, composed by 'Marandu' grass cultivated in full sun. Variables of the leaf anatomy of 'Marandu' grass were evaluated for shading interference by trees. The distance of 'Marandu' grass plants from the eucalyptus lines interfered with the leaf blade anatomy of the forage, and the highest modifications occurred in linear measures and tissue proportions in the arrangements with the highest eucalyptus density. The shading interference of eucalyptus on the anatomical characteristics of leaf blades of 'Marandu' grass depends on the adopted arrangement. This occurs due to the grass adaptation to the low-light incidence, with a consequent reduction in its physiological activity and growth. Resumo: O objetivo deste trabalho foi avaliar os efeitos de diferentes arranjos de plantas de eucalipto sobre as características morfoanatômicas de lâminas foliares de plantas de capim 'Marandu' [(Urochloa brizantha (Syn. Brachiaria brizantha)] cultivadas em sistemas agrossilvipastoris. O experimento foi estabelecido em condições de campo, em um delineamento de blocos ao acaso, com quatro repetições, em que as parcelas foram representadas pelos espaçamentos de plantio de eucalipto (12x2 e 12x4 m), e as subparcelas, pela distância entre o capim 'Marandu' e as fileiras de eucalipto (6, 4 e 2 m). Adicionou-se um controle apenas com capim 'Marandu', cultivado a sol pleno. As variáveis de anatomia foliar do capim 'Marandu' foram avaliadas quanto à interferência do sombreamento pelas árvores. A distância entre as plantas de capim 'Marandu' e as linhas de eucalipto interferiram na anatomia da lâmina foliar da forragem, e as maiores modificações ocorreram nas medidas lineares e proporções teciduais nos arranjos com maior densidade de eucalipto. A interferência do sombreamento pelo eucalipto nas características anatômicas das folhas de capim 'Marandu' depende do arranjo adotado. Isto ocorre em razão da adaptação do ca