Tillering dynamic and structural characteristics of tropical grasses under cutting management / Dinâmica de perfilhamento e características estruturais de gramíneas tropicais sob corte

This paper aimed to evaluate the dynamics of tillering, tiller density and structural characteristics of Brachiaria brizantha, Panicum maximum and Cenchrus ciliaris under a cutting regime. The utilized design was randomized blocks with six treatments (cultivars) and three replications. The evaluations were conducted from May to September 2011, with the data grouped into two periods, rainy season and beginning of the dry season. The greatest tiller population density was observed in the Massai cultivar, averaging 1,019 tillers.m-2. The tiller mortality rate was higher for Mombaça and less for Piatã cultivars. The highest values for forage mass, percentage of leaf blades and relations between green mass:dead mass were observed in Brachiaria brizantha and Panicum maximum cultivars. Panicum and Brachiaria cultivars have shown to be promising for cultivation in the transition areas between the Atlantic Forest and Caatinga biomes in Northeastern Brazil. Cenchrus cultivars are less productive in environments without restriction of abiotic factors.

Objetivou-se avaliar a dinâmica de perfilhamento, a densidade populacional de perfilhos e as características estruturais de cultivares de Brachiaria brizantha, Panicum maximum e Cenchrus ciliaris em regime de corte. O delineamento utilizado foi em blocos ao acaso com seis tratamentos (cultivares) e três repetições. As avaliações foram realizadas de maio a setembro de 2011, sendo os dados agrupados em dois períodos, águas e início da seca. A maior densidade populacional de perfilhos foi observada na cultivar Massai com média de 1019 perfilhos/m2. A taxa de mortalidade de perfilhos foi maior na cultivar Mombaça e menor na Piatã. Os maiores valores para massa de forragem, percentual de lâminas foliares e relações entre massa verde:massa morta foram observados nas cultivares de Brachiaria brizantha e Panicum maximum. As cultivares de Panicum e Brachiaria se mostraram promissoras à utilização em áreas de transição entre os biomas de Mata Atlântica e Caatinga na Região Nordeste do Brasil. As cultivares de Cenchrus são menos produtivas em ambientes sem restrição de fatores abióticos.

Herbicidas inibidores da accase em plantas de Cenchrus echinatus em estresse hídrico / Accase-Inhibitor herbicides in plants of Cenchrus echinatus in water stress

Este projeto objetivou relacionar a eficiência de controle de herbicidas inibidores da ACCase aplicados em pós-emergência em plantas de Cenchrus echinatus submetidas a diferentes teores de água no solo. Os experimentos foram conduzidos em casa de vegetação, com a aplicação de três diferentes herbicidas (fluazifop-p-butil, haloxyfop-methyl e sethoxydim + óleo mineral Assist). O delineamento experimental utilizado para cada herbicida foi inteiramente casualizado, com 4 repetições, constituído de um fatorial 3 x 4, sendo a combinação de três manejos hídricos (-0,03; -0,07 e -1,5 MPa) e quatro doses destes produtos (100, 50, 25 e 0% da dose recomendada). A aplicação dos herbicidas foi efetuada no estádio vegetativo de 2-3 perfilhos. Os manejos hídricos foram iniciados no estádio de desenvolvimento de duas folhas, repondo-se a água até o solo atingir o potencial de -0,01 MPa, quando este chegasse à tensão pré-determinada para cada manejo hídrico. As avaliações visuais de fitotoxicidade foram realizadas aos 7, 14, 21 e 28 dias após a aplicação e a matéria seca das plantas ao final destas. A eficiência de controle dos diferentes herbicidas foi influenciada pelos manejos hídricos sendo menor em plantas mantidas em potencial mínimo de água no solo de -1,5 MPa. Todos os herbicidas testados apresentaram controles insatisfatórios em aplicações tardias (plantas com 2-3 perfilhos).

This project aimed to relate the efficiency of control of ACCase inhibiting herbicides applied post-emergence in Cenchrus echinatus under different soil water contents. The experiments were conducted in a greenhouse, with the application of three different herbicides (fluazifop-p-butyl, haloxyfop-methyl and sethoxydim + oil Assist) and the experimental design for each herbicide was completely randomized design with four replications, consisting a 3 x 4 factorial, with the combination of water management strategies (-0.03, -0.07 and -1.5 MPa) and four doses of these products (100, 50, 25 and 0% of the recommended dose). Herbicide application was made at vegetative stage of 2-3 tillers. The water management strategies were initiated in the development stage of two leaves, replacing the water until the soil reaches the potential of -0.01 MPa, when it came to severe pre-determined for each water management. The physiological parameters evaluated were: photosynthetic rate, stomatal conductance, transpiration, leaf temperature and plant dry matter. The visual assessments of phytotoxicity were performed at 7, 14, 21 and 28 days after application. The efficiency of these herbicides was influenced by soil management and water lowest in plants grown in the minimal potential of water in the soil of -1.5 MPa. All the herbicides were unsatisfactory controls in applications late (2-3 tiller plants).

Características morfogênicas e acúmulo de forragem de gramíneas forrageiras sob corte / Accumulation of forage and morphogenic responses in forage grass by cutting

Objetivou-se avaliar e as características morfogênicas e o acúmulo de forragem de três gêneros de gramíneas, Brachiaria, Panicum e Cenchrus em regime de corte. O delineamento utilizado foi em blocos ao acaso com parcelas subdivididas. Houve efeito de interação entre cultivar e época de avaliação para a taxa de aparecimento de folhas, alongamento de colmos, duração de vida das folhas e senescência de folhas. As cultivares Áridus e Biloela (Cenchrus) apresentaram os menores Filocronos, seguidos da cultivar Piatã (B. brizantha). A taxa de alongamento de folhas e seu comprimento final foram maiores no período das chuvas, para todas as cultivares. As cultivares Massai e Mombaça apresentaram os maiores comprimentos de folha, mas os menores números de folhas vivas por perfilho. As cultivares Áridus e Biloela as menores taxas de acúmulo de lâminas foliares em relação ás demais. O maior fluxo de tecidos observado no gênero Cenchrus, não foi suficiente para superar a maior de produtividade das cultivares dos gêneros Panicum e Brachiaria.

This study aimed to evaluate the accumulation of forage and the morphogenesis of three genera Brachiaria, Cenchrus and Panicum in cutting regime. The experimental design was a randomized block with three replicates and six treatments. After each cut were evaluated for forage production, appearance and elongation rates of leaves and stem final leaf length, number of green leaves, leaf life span, rate of senescence of leaves. For herbage accumulation rate was higher in the cv. Xaraes, which is more than double the cumulative cv. Aridus, the lowest rate among cultivars. As for leaf appearance rate and leaf elongation was higher in the rainy season only for cultivars Aridus Biloela and the other showed no difference between the evaluation periods. Cultivars Aridus, Biloela and Piata obtained the highest number of leaves per tiller, differing from Mombaça, Massai and Xaraes that showed the lowest values. The lower values of leaf life span were found in the rainy season to cultivate Aridus, Biloela and Mombaça. Except Aridus, which showed a higher rate of senescence of leaves in the rainy season, others grasses did not differ between the evaluation periods. We conclude that the highest rates of leaf appearance and number of green leaves found on the cultivars of the genus Cenchrus, were not enough to overcome the greatest potential for producing forage cultivars of the genera Panicum and Brachiaria. The grasses tested showed potential for use in the Northeast, but were influenced by seasons, mainly due to a decrease in rainfall.

Consumo, digestibilidade aparente de nutrientes e balanços de nitrogênio e hídrico de ovinos alimentados com silagens de cultivares de capim-búfel / Intake, apparent digestibility of nutrients and nitrogen and water balances of sheep fed with buffel grass cultivars silages

Objetivou-se no presente estudo determinar o consumo, digestibilidade aparente da matéria seca e nutrientes, além dos balanços de nitrogênio (BN) e hídrico (BH), de ovinos alimentados com silagens de capim-búfel. As silagens das cultivares de capim-búfel avaliadas foram Tanzânia, Buchuma e Biloela. Utilizaram-se 21 ovinos, machos, castrados, mestiços Santa Inês x Sem Padrão de Raça Definido, com peso corporal médio inicial de 31,8±3,16kg, mantidos em gaiolas metabólicas. Foi utilizado um delineamento inteiramente casualizado com sete repetições. Não foram observadas diferenças nos consumos de MS em g/dia (919,2) e porcentagem do peso corporal (2,9). De modo geral, os coeficientes de digestibilidade da matéria seca variaram de 37,7% a 60,0%. Os BN e BH foram positivos, sendo observados maiores valores de BN para os ovinos alimentados com silagens de capim-búfel dos cultivares Tanzânia (5,1g/dia) e Biloela (3,9g/dia), e maiores BH para os animais alimentados com silagens de capim-búfel dos cultivares Buchuma (1,38kg/animal/dia) e Biloela (1,42kg/animal/dia). Os cultivares de capim-búfel Tanzânia, Buchuma e Biloela apresentaram bom valor nutritivo, sendo que o capim-búfel na forma de silagem promoveu 60% do consumo total de água diário do animal.

The objective of this present experiment was to determine intake and apparent digestibility of dry matter and nutrients, nitrogen (NB) and water balances (WB) of sheep fed with buffel grass silages. The buffel grass cultivars used were Tanzania, Buchuma and Biloela. 21 male, castrated, crossbred Santa Ines x Non defined genotype sheep, with initial body weight of 31.8±3.16kg were used, kept in metabolic cages. The experimental design was completely randomized with seven replicates. No differences were observed in dry matter intake in g/day (919.2) and % of body weight (2.9). In general, digestibility coefficients of dry matter varied from 37.7% to 60.0%. The NB and WB were positive, with higher NB values in sheep fed with Tanzania (5.1g/day) and Biloela (3.9g/day) and higher WB in animals fed with Buchuma (1.38kg/animal/day) and Biloela (1.42kg/animal/day). All cultivars of buffel grass evaluated (Tanzania, Buchuma and Biloela) presented adequate chemical composition, where the silage of buffel grass used corresponded to 60% of the total daily water intake by sheep.

Insights and lessons learned from the long-term rehabilitation of an iron ore mine

A long-term study was conducted between 1985 and 2003 on rehabilitation trials at Sishen Iron Ore Mine, South Africa, to identify grass species that would survive in the artificial growth medium applied to the sites, and to determine the most suitable medium for sustainable vegetation growth. Vegetation establishment was tested at slopes of 18° and 34° and with five different cover materials. After 17 years of rehabilitation, investigations showed that weathered limestone sloped at 18° produced the highest percentage of plant cover and least erosion. Sixteen grass species were introduced and identified in the survey, with Eragrostis sp. and Cenchrus ciliaris as the dominant species. In 2004, new trials were initiated at the same mine to evaluate the effectiveness of different seeding methods and supplementation of the growth medium with organic material. After 4 years, hydro seeding was found to be the best method to distribute seeds evenly and to ensure uniform vegetation growth. Different engineering designs, such as changing the contour length and slope, had little influence on the measured parameters. A total of 28 grass species were identified in the sampling plots, with Enneapogon cenchroides and Cenchrus ciliaris as the dominant ones. Dehydrogenase activity was used as a proxy for microbial activity, and a positive association was observed between microbial activity and percentage organic carbon, emphasising the importance of soil organic matter in the soil development process

Efeitos da suplementação com fósforo em caprinos no semiárido do nordeste brasileiro / Effect of phosphorus supplementation for goats in the Brazilian semiarid region

To evaluate the effect of phosphorus supplementation for goats grazing for the semiarid region, one group of 16 recently weaned Moxotó goats was supplemented with a mineral supplement containing Na, Cl, Zn, Cu, Se, Co, and P during 240 days. Another similar group was supplemented with a similar mineral supplement without P. The mean daily consumption of supplement by animal was of 7.09±2.77g and 7.67±3.14g for the groups with and without P, respectively. The mean weight gain of the P supplemented group (45.20±5.56g) was significantly higher (P<0.05) than the non-supplemented group (40.03±2.80g). The average total P in soil was 30.8mg/kg and in the pasture 0.13 percent in dry matter. These results demonstrate the occurrence of P deficiency in some areas of the Brazilian semiarid region.

Emergência de capim-carrapicho e picão-de-flor com diferentes profundidades de semeadura em duas épocas / Emergence of Cenchrus echinatus L. and Cosmos sulphureus Cav. with different sowing depths in two seasons

Com o objetivo de estudar a emergência de plântulas de Cenchrus echinatus e Cosmos sulphureus em resposta à época e à profundidade de semeadura, foram realizados dois experimentos em condições ambientais não controladas, aguadas diariamente, nos meses de junho e setembro de 2009. Sementes de C. echinatus e C. sulphureus foram semeadas em diferentes profundidades (0, 1, 3, 5, 7 e 9 cm). Os experimentos foram conduzidos em vasos com 5 repetições, contendo 50 sementes por vaso. Diariamente, durante 21 dias, as plântulas emergidas foram contadas e cortadas rente ao solo, seguido de avaliação de porcentagem de emergência e índice de velocidade de emergência (IVE). Os maiores percentuais de emergência e maiores IVE foram observados até 5 cm de profundidade e a espécie C. sulphureus se mostrou mais sensível às variações de temperatura em decorrência da época de semeadura do que a espécie C. echinatus.

With the purpose to study the emergence of Cenchrus echinatus L.and Cosmos sulphureus Cav. in response to time and depth of sowing, two experiments were conducted in uncontrolled environmental conditions in the months of June and September 2009. Cenchrus echinatus L.and Cosmos sulphureus Cav seeds were sown at different depths (0, 1, 3, 5, 7 and 9 cm). The experiments were conducted in pots, with five replications of 50 seeds per pot, followed by evaluation of the emergence percentage and emergence speed index (ESI). The highest percentage of emergency and higher EVR were observed up to 5 cm depth and the species Cosmos sulphureus Cav. was more sensitive to temperature variations due to the time of sowing of the species C. equinatus

Effect of water stress on carbon isotope discrimination and its relationship with transpiration efficiency and specific leaf area in Cenchrus species.

Carbon isotope discrimination (CID) has been proposed in estimating transpiration efficiency (TE) in plants indirectly To identify variations for TE and specific leaf area (SLA) and their association with CID, a glasshouse experiment was conducted using six prominent species of Cenchrus. A significant increase in TE (3.50 to 3.87 g kg(-1)) and decrease in SLA (219.50 to 207.99 cm2 g(-1)) and CID (13.72 to 13.23% per hundred) was observed from well watered to stress condition. Results indicated a direct relationship of SLA with CID (r = 0.511* and 0.544*) and inverse relationship between TE and CID (r = -0.229 and -0.270) However the relationship of TE with CID was insignificant. A positive and significant relationship was visualized between TE and dry matter production in both control (r = 0.917**) and stress (0.718**) treatments. Relationships of total dry matter with SLA and CID were monitored insignificant and negative in control and positive in stress treatment indicated difference in dry matter production under two treatments. It seems that, in Cenchrus species, CID was influenced more by the photosynthetic capacity than by stomatal conductance, as indicated by its positive relationship with SLAin both control (r = 0.511) and stress (r = 0.544) conditions and negative relationship with root dry matter production under control (r = -0.921**) and stress (r = -0.919***) condition. Results showed good correspondence between CID and SLA, indicating that lines having high TE and biomass production can be exploited for their genetic improvement for drought.