Márcio Vieira da Cunha

Potential of Caatinga forage plants in ruminant feeding

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 N2 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.

Variability and heritability of morphologic characters in elephant grass clones in the Forest Zone in Pernambuco

Esta pesquisa foi realizada para avaliar a variabilidade e herdabilidade de caracteres morfologicos de 54 clones de capim-elefante na Zona da Mata de Pernambuco (tres testemunhas locais e os demais provenientes da RENACE/CNPGL). Utilizou-se delineamento em blocos casualizados com testemunhas adicionais. Foram realizados tres cortes de avaliacao aos 60 dias de crescimento. Houve diferencas significativas para diâmetro de colmo, densidade de perfilhos basais e aereos, largura da folha 3, comprimento da folha 5, porcentagem de lâminas foliares, porcentagem de colmo e relacao lâmina foliar/colmo. Os clones da RENACE sao semelhantes aos tradicionalmente cultivados nas condicoes da Zona da Mata de Pernambuco quanto a maioria dos caracteres morfologicos. A cultivar Pioneiro floresceu precocemente nas condicoes ambientais deste estudo. As caracteristicas numero de perfilhos basais e aereos/metro apresentaram alta herdabilidade, o que evidenciando pouca influencia do ambiente na variabilidade entre clones. Considerando a variabilidade entre os clones da RENACE para numero de perfilhos basais e aereos/metro e relacao folha/colmo e a alta herdabilidade desses caracteres, e possivel obter ganhos geneticos para essas caracteristicas no melhoramento do capim-elefante na regiao da Zona da Mata de Pernambuco.

Association between the morphological and productive characteristics in the selection of elephant grass clones

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 Pennisetum cp. clones. The canonical correlations were evaluated and the path analysis was made from the simple genotypic correlation matrix between the morphological and productive characteristics of eight Pennisetum sp. clones (Taiwan A-146 2.37, Taiwan A-146 2.27, Taiwan-146 2.114, Merker Mexico MX 6.31, Mott, HV-241, Elefante B and IRI-381). The canonical correlations were significant at 1% probability by the Chi-square test. The first pair of canonic factors, with correlation of 0.9999, related the plants with the highest dry matter content to plants with lower leaf area indexes, light perception and leaf angle. The second pair of canonic factors, with correlation of 0.9999, related the plants with the highest dry matter production to the plants with higher basal tiller density, height, and low green leaf number per tiller. The results of the path analysis indicated that the light interception is determinant in dry matter content expression of Pennisetum sp. clones, while the basal tiller density and plant height are responsible for dry matter production in these clones.

Análise de trilha em caracteres produtivos de Pennisetum sob corte em Itambé, Pernambuco

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 m2 with 2 m2 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.

Variabilidade e herdabilidade de caracteres qualitativos relacionados à qualidade de forragem de clones de capim-elefante na Zona da Mata de Pernambuco

The objective of this research was to evaluate variability and heritability of quantitative traits related to forage quality of 32 clones of elephant grass (three local controls, from Zona da Mata de Pernambuco, and the remaining from RENACE/CNPGL). A complete randomized design was used with additional controls and analyses of variance was applied by using the procedure of families with controls between rows. Evaluation was performed during the dry period, at 60 days of growth. It was observed significant differences among clones for the traits acid detergent of leaf blade and stem organic matter, with means of 34.05 and 78.83%, respectively. In general, heritability of qualitative traits was low, including null values for crude protein and neutral detergent fiber of leaf blade and in vitro digestibility of dry matter of leaf blade and stem. Chemical composition and digestibility of evaluated clones were similar. There are few possibilities of gain in selection for qualitative traits considering the low variability and heritability of the studied characters.

Repetibilidade e respostas de características morfofisiológicas e produtivas de capim-elefante de porte baixo sob pastejo

The objective of this study was to estimate the coefficients of repeatability and determination (R2) and the minimum number of measurements necessary to predict the real value of morphophysiological and yield variables, as well as the responses to sheep-grazing of dwarf elephant grass pasture. The experiment was carried out in a randomized block design with five treatments - Taiwan A-146 2.27, Taiwan A-146 2.37, Taiwan A-146 2.114, Merker Mexico MX 6.31 and Mott - and four replicates, over five grazing cycles, between September 2008 and April 2009. Mean sward height, leaf area index (LAI), light interception (LI), mean leaf angles (MLA), silage accumulation (SA) and silage accumulation rate (SAR) were evaluated. For the variables LAI, IL and mean sward height of plants, in long cycles, only one measurement was necessary (R2 = 80%) to place them among the most predictable characteristics in the evaluation of elephant grass clones. Assessments for SA and SAR need longer experimental periods for greater reliability in the estimation of response variables. In dwarf elephant grass, light interception increases with sward height and LAI.

Estimates of genetic parameters under two evaluation strategies in intra and interespecific hybrids of elephant grass

The objective of this work was to evaluate the genetic parameters estimated in intra and interespecific hybrid families of elephant grass under two evaluation strategies: per se and genetically stratified mass selection. Ten families of intraespecifc hybrids and ten families of interespecific hybrids were used. The characteristics evaluated were the following: plant height, plant agronomic score, dry matter content and dry matter production. It was estimated, for genetic parameters, heritability in the wide sense, variance, genetic and experimental variation coefficient and genetic, phenotypic and environmental correlation. The experiment was evaluated in a random block design with three repetitions. Greater genetic variability for the studied characteristics were observed among the interespecific hybrids of elephant grass and pearl millet in comparison to the intraespecifc hybrids of elephant grass. Heritability showed higher percentages for per se strategy among the studied hybrids. Genetically stratified mass selection is less effective in removing the environmental effects aiming at improving experimental precision.

Genótipos de capim-elefante sob pastejo no período de seca na Zona da Mata de Pernambuco: fatores relacionados à eficiência de pastejo

The experiment was carried out to evaluate factors related to the grazing efficiency of five Pennisetum sp. genotypes (CE 08 A.D., Venezuela, HV-241, Elephant B and Hexaploide) during the dry period in the Forest Zone of Pernambuco. Genotypes were managed under rotational stocking (44 days of resting and four days of grazing period). It was used a split-plot arrangement in a complete randomized block design (genotypes represented the plots; grazing cycles, the subplots). Six replications were used to determine pre-grazing total leaf blade mass and green and senescent leaf blade mass. Four replications were used for leaf blade accumulation and grazing efficiency and, for these variables, it was used a complete randomized blocks design. The CE 08 A.D. and Elephant B presented greater pre-graze total leaf blade mass, green leaf blade, green leaf blade accumulation, and grazing efficiency, with averages of 1,374 kg DM/ha, 737 kg DM/ha, 654 kg DM/ha/44 days and 80% of the green leaf blade accumulation, respectively. The highest grazing efficiency (100% of the green leaf blade accumulation) occurred at the HV-241 pastures. This high grazing efficiency was associated to the low green leaf blade accumulation (155 kg of MS/ha/44 days). The lowest grazing efficiency was observed for the Hexaploide (59% of the green leaf blade accumulation), possibly due to high losses under grazing (30% of the pre-grazing total leaf blade mass). The green leaf blade mass decreased mostly until the second grazing day, while the losses of total leaf blade were higher in the second and third grazing days. The genotypes CE 08 A.D. and Elephant B presented potential to be used under rotational stocking, in the Pernambuco Forest Zone.

Estabilidade e adaptabilidade de clones de Pennisetum sp. sob pastejo: Mancha ocular

EnglishThe work was conducted at the Experimental Station of Itambe, of the Pernambuco State Agricultural Research Enterprise, to evaluate the adaptability and stability of Pennisetum sp. clones under pasture and Helminthosporium sp. incidence. The experimental design was randomized blocks, with 5 replicates and 16 treatments. Plots measured 5x5 m with one meter between rows spacing. Helminthosporium sp. incidence was studied by note scale according to spot presence on the leaves of the studied genotypes. With regards to genotype adaptability, Mineirao (0.31), Taiwan A 25 P 18 (0.50), SEA P 36 (0.28), SEA P 37 (0.38) and Gigante de Pinda P 73 (0.46) had regression coefficients below population average (β 1i ), indicating unfavorable environment adaptability. Genotypes Pusa Napier 1 P 25 (1.58), Pusa Napier 1 P 27 (1.55), Pusa Napier 1 P 28 (1.47), Pusa Napier 1 P 32 (1.28), Pusa Napier 1 P 33 (1.22), SEA P 35 (1.60), HV 241 (1.41) and Pioneiro (1.36) had better response in favorable environments, and Pusa Napier 1 P 31 and Roxo de Botucatu P 80 had ample adaptability. Hybrid HV 241 and Pioneiro had significant deviations from regression by the F test (p portuguesFoi realizado um trabalho na Estacao Experi- mental de Itambe, do Instituto Agronomico de Pernambuco-IPA, com o objetivo de avaliar a adaptabilidade e estabilidade de clones de Pennisetum sp. sob pastejo, considerando a incidencia de Helminthosporium sp. O deline- amento experimental foi de blocos ao acaso com cinco repeticoes e 16 tratamentos. As parcelas mediam 5x5 m com espacamento de um metro entre linhas. A incidencia de Helminthosporium sp. foi estudada por uma escala de notas confor- me a presenca de manchas nas folhas dos genotipos testados. Com relacao a adaptabilidade dos genotipos, o Mineirao (0,31), Taiwan A 25 P 18 (0,50), SEA P 36 (0,28), SEA P 37 (0,38) e Gigante de Pinda P 73 (0,46) apresentaram coefi- cientes de regressao abaixo da media populacional (β 1i ), indicando adaptabilidade a ambientes desfavoraveis. Os genotipos Pusa Napier 1 P 25 (1,58), Pusa Napier 1 P 27 (1,55), Pusa Napier 1 P 28 (1,47), Pusa Napier 1 P 32 (1,28), Pusa Napier 1 P 33 (1,22), SEA P 35 (1,60), HV 241 (1,41) e Pioneiro (1,36) responderam melhor em ambientes favoraveis, e o Pusa Napier 1 P 31 e Roxo de Botucatu P 80 apresentaram ampla adaptabilidade. O hibrido HV 241 e o Pioneiro apresentaram desvios significativos da regressao pelo teste F (p

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

The experiment was carried out to study structural and morphologic characteristics of five Pennisetum sp. genotypes (CE 08 A.D., Venezuela, HV-241, Elephant B and Hexaploide) under grazing during the dry period in Pernambuco Forest Zone. Genotypes were managed under rotational stocking (44 days of resting and four days of grazing period). The experimental design was randomized blocks in a split plot arrangement, and four replications. The genotypes represented the plots, and grazing cycles, the subplots. There was variation in the structural and morphologic characteristics of the Pennisetum sp. genotypes. The CE 08 A.D. and Elephant B presented high density of green leaf blade, low percentage of dead material and high density of remaining basal tillers and new aerial tillers, with averages of 5.0±0.4 kg DM/ha/cm; 33±0.2%; 22±0.2 and 146±0.4 tillers/m2, respectively. The HV-241 presented high participation of dead material in its aerial biomass (55.6±0.3%) due to high tiller mortality (19±0.3 and 114±0.4 basal and aerial dead tillers/m2, respectively). The genotypes CE 08 A.D. and Elephant B had been distinguished as promising to be used under grazing in the dry period. The genotype HV-241, elephantgrass hybrid with pearl millet, was more affected by water stress during the dry period of the year.