-Caatinga is the most important biome for the livestock in the Brazilian semi-arid region. This review paper aimed to present information on different forage aspects of caatinga vegetation for ruminant feeding. Caatinga vegetation is formed mainly by shrubs and small trees, usually presenting thorns, deciduous leaves, and leaf abscission occurring frequently at the onset of the dry season. Additional components of the botanical composition in this biome includes the families cactaceae, bromeliaceae, and a herbaceous component formed by grasses, legumes, and forbs, often presenting annual cycle. Quantitative information of caatinga vegetation is scarce in the literature, mainly for the herbaceous stratum. Methodological aspects such as lack of standardization across evaluations make comparison regarding forage potential of caatinga plant species difficult. Index species must be identified within each caatinga type. Quantitative aspects of biological N 2 fixation by caatinga species have not been extensively studied. Regarding forage nutritive value, it is necessary to study N availability for ruminants in caatinga plants, since large proportion of this element may bind to fiber components (ADIN). Manipulation of caatinga vegetation is an alternative to change forage quantity and quality for grazing animals, affecting their performance as a result. Studies measuring qualitative and quantitative variability of native forage resources from caatinga are mandatory in order to improve animal feeding management, with the ultimate goal of creating sustainable animal production based on caatinga vegetation.Key Words: chemical composition, native plant, quantitative aspect, semi-arid Potencial de plantas forrageiras da Caatinga na alimentação de ruminantesRESUMO -Considerando a importância do bioma Caatinga na pecuária da região semiárida brasileira, o presente trabalho objetivou apresentar informações sobre diferentes aspectos forrageiros de plantas da caatinga, com vistas à alimentação de ruminantes. A vegetação de caatinga é constituída por arbustos e árvores de pequeno porte, geralmente dotados de espinhos, sendo caducifólias, em sua maioria, perdendo suas folhas no início da estação seca. Complementam ainda a composição botânica desse bioma, cactáceas, bromeliáceas e um componente herbáceo, formado por gramíneas e dicotiledôneas, predominantemente anuais. Informações, principalmente sobre o aspecto quantitativo de plantas da caatinga, notadamente para o estrato herbáceo ainda são escassas. Dificuldades e desuniformidade de metodologias de avaliação, além de falta de detalhamento das metodologias utilizadas, dificultam a comparação de resultados quanto ao potencial forrageiro de algumas plantas. A fixação biológica de N atmosférico por espécies da caatinga até o momento foi pouco estudada, notadamente quanto aos aspectos quantitativos.Faz-se necessária uma avaliação mais profunda sobre a disponibilidade do nitrogênio, uma vez que parte deste pode estar ligado a parede celular (NIDA). A manipulação da caatinga ...

-The objectives in this work were to study the association between the morphological and productive characteristics in Pennisetum sp. clones, and to identify the morphological characteristics responsible for the productivity in

The objective of this work was to characterize morphologically elephant grass (Pennisetum purpureum) genotypes and to estimate their proportions of leaf blade tissues under grazing. Two tall varieties (Elephant B and IRI-381) and three short ones (Mott, Taiwan A-146 2.37, and Taiwan A-146 2.114) were evaluated under intermittent sheep grazing as to the following morphological characteristics: plant height, internode length, and leaf blade/culm ratio. Moreover, the proportions of the following leaf blade tissues were estimated: sclerenchyma, adaxial and abaxial epidermis, bulliform cells, vascular bundles, phloem, vascular sheath, xylem, and mesophyll. The short varieties were 28.6% shorter than the tall ones and showed higher leaf blade/culm ratio; Mott and Taiwan A-146 2.114 had the shortest internodes of 3.9 and 4.7 cm, respectively, over ten grazing cycles. The clones differed regarding their proportions of leaf blade tissues, except for abaxial epidermis, phloem, and xylem. The differences in morphological characteristics indicate that the short clones Mott and Taiwan A-146 2.114 are better adapted to sheep grazing, and, therefore, may be recommended for the improvement of pastures.

Adaptability is the capacity of a genotype to respond favorably to changes in the environment, while stability is the capacity to have highly predictable performance in different environmental conditions. In this study, the stability and adaptability of eight Pennisetum spp. clones were assessed. Genotypes analyzed in this research included five dwarf elephantgrass (Pennisetum purpureum Schumach.) cultivars (Taiwan 2.27, Taiwan 2.37, Taiwan 2.114, Merker México 6.31, and Mott), two tall elephantgrass cultivars (IRI 381 and Elephant B), and one interspecific hybrid (HV 241) of elephantgrass and pearl millet [P. purpureum × P. glaucum (L.) R. Brown]. Adaptability and stability parameters were estimated for the following variables: herbage mass (HM), herbage accumulation rate (HAR), number of green leaves per tiller (NL/T), number of tillers (NT), and leaf/stem ratio. Interaction between clones and grazing periods occurred (P ≤ 0.05) for all variables. Herbage mass ranged from 2180 kg dry matter (DM) ha−1 (Taiwan 2.37) to 3383 kg DM ha−1 (Mott), averaging 2796 kg DM ha−1. Except for HV 241, which displayed specific adaptability to a favorable environment in HM and NT, the clones displayed wide adaptability. Dwarf genotypes (Taiwan 2.27, Taiwan 2.114, and Mott) displayed greater (P ≤ 0.05) capacity of leaf production per tiller than the other entries. Mott and Taiwan 2.114 were selected for the next phase of the breeding program on the basis of stability, HAR, and NL/T.

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RESUMO -Objetivou-se obter estimativas de coeficientes de correlação genética e avaliar os desdobramentos das correlações em efeitos diretos e indiretos (análise de trilha) das variáveis independentes explicativas sobre a produção de matéria seca (variável dependente principal) em cinco clones de capim-elefante. Foram realizados cinco cortes a cada 60 dias nas condições edafoclimáticas da Zona da Mata de Pernambuco. Cada parcela experimental apresentou 24 m 2 , com 2 m 2 de área útil. Houve alta correlação entre quase todas as variáveis explicativas e a variável principal. Entretanto, a característica número de lâminas foliares por perfilho explicou melhor o potencial de produção de matéria seca e atuou de forma direta e indireta sobre as variáveis explicativas.Palavras-chave: capineira, correlação, matéria seca, melhoramento Path analysis in productive characters of Pennisetum under cut in Itambé-PEABSTRACT -This work aimed to estimate the correlation coefficients, determining the direct and indirect effects (path analysis) of explanatory independent variables on total dry matter production (main dependent variables) of five elephant grass clones in five cuts accomplished at the forest zone of Pernambuco. Each experimental plot measured 24 m 2 with 2 m 2 of utile area. There was high correlation between almost all the independent variables and the main variable. The characteristic leaf blade number per tiller, however, explained better the potential of dry matter production and leaf blade dry matter production, acting, respectively, in a direct and indirect way on the explanatory variables.

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Elephant grass (pennisetum purpureum schum.) has been grown only in cut-and-carry systems for a long time. However, interest in its grazing management has been increasing because of the selection of short-sized genotypes, which have gained new relevance since 1988 with the registration of ‘mott’ grass. in this sense, tall and short-sized genotypes present important differences in morphology, quality and productivity; although, environmental factors also exert influence on these aspects. This review aimed to approach how the elephant grass size can influence the morphophysiological characteristics, management decisions, and exploitation of this species. the morphophysiological aspects and the elephant grass sizes are important to direct their utilization in the different production systems. The research results from previous decades suggest that the particularities of the tall-sized genotypes, such as great forage accumulation, high organic reserves content, and stem elongation, favor their management in cut-and-carry systems and industrial sectors. Conversely, the short-sized elephant grass genotypes present aspects as higher leaf proportion in the harvested forage, leaf/stem ratio, and tillering. these factors facilitate their exploitation in grazing systems.