Luciano de Melo Moreira

Características morfogênicas e estruturais de capim-massai submetido a adubação nitrogenada e desfolhação

This work was carried out to evaluate the morphogenetic and structural characteristics of the hybrid Panicum maximum x Panicum infestum cv. Massai in response to four nitrogen doses (0, 40, 80 and 120 mg/dm3) and three defoliation intervals (two, three and four completely expanded leaves), in a 4 x 3 factorial treatment combination. The experiment was carried out in greenhouse according to a completely randomized design, with four replications. Sowing was achieved in plastic tray filled with sand and seedlings were transplanted to pots with 5.8 dm3 of soil. Pots were thinned to three plants/pot. The phosphate and potash fertilization was accomplished according to soil fertility analysis. The nitrogen fertilization was split in four applications in aqueous solution, according to the experimental doses. As the plants presented the number of expanded leaves, indicating their defoliation interval, they were harvested to 5 cm from soil level; this harvest marked the beginning of the evaluation period of the morphogenetic and structural characteristics of the grass. At the end of these evaluations, the plants were harvested, dried and weighted. Nitrogen fertilization doses had marked effects on the morphogenetic and structural characteristics of Massaigrass, as well as on its shoot dry weight. Leaf elongation rate (TAlF) showed linear increase of 64% to N doses. The phyllochron decreased as nitrogen dose increased. Shoot dry matter weight and lamina:stem ratio increased linearly with the increment of N doses but decreased as the number of expanded leaves increased before harvest.

Morphogenetic and structural characteristics of xaraésgrass submitted to nitrogen fertilization and defoliation

The morphogenetic and structural traits of Brachiaria brizantha cv. Xaraes submitted to the treatment combinations of four nitrogen rates (0, 40, 80 and 120 mg/dm3) and three defoliation frequencies (two, four and five completely expanded leaves) were evaluated according to a 4 x 3 factorial arrangement. The experiments were conducted in a greenhouse, with the treatments arranged as factorial combination. The experimental design was completely randomized, with four replications. After thinning, three seedlings were left per pot (5,8 dm3). The phosphate fertilization was performed according to the soil fertility. The pots were fertilized with phosphorus and potassium, according to soil fertility. Nitrogen fertilization was split in four applications and applied in aqueous solution. When the plants reached the number of expanded leaves (defoliation moment), they were cut at 5 cm height from soil level before evaluation of morphogenetic and structural traits in the aftermath. Significant nitrogen effect was observed on morphogenetic and structural characteristics of xaraesgrass and on DM yield, except on root DM. Leaf elongation rate (LER) increased linearly up to 37% at the N rate of 120 mg/dm3. Defoliation influenced leaf elongation rate, phyllochron, blade length, number of live leaves per tiller, senescence rate and dry matter yield of shoot and root.

Demografia de perfilhos basilares em pastagem de Brachiaria decumbens adubada com nitrogênio

It was evaluated tiller appearance, mortality and survival rates, the flowering percentage and the population density of basal tillers in pasture of Brachiaria decumbens under four doses of nitrogen (75, 150, 225 and 300 kg/ha/year), in three periods of the year: February to April, May to August and September to November. The experiment was conducted in a completely randomized design with periods as a split plot feature, with two replications. The nitrogen fertilization was split in three applications the first in December (2002), second in January (2003) and the third in March (2003). The evaluation of demography of basal tillers was accomplished by initial demarcation of all the tillers contained within a ring of PVC, followed by monthly identification of new tillers with wires of different colors. Evaluation of the population density of basal tillers (vegetative, reproductive and dead tillers) was performed from samples of plants harvested within 25 x 25 cm three squares from each paddock. The nitrogen fertilization positively influenced the tiller appearance, mortality and survival rates, number of vegetative tillers and the tillers mortality in the generations 1 and 2. Rates of tiller appearance were higher in February/April and September/November, while the rate of tiller mortality was higher in February/April period. Tiller population density also varied over the periods, higher figures being observed in Febrary/April period. The flowering of the Signalgrass flowering was most intense from February to May.

Bovine production on deferred signalgrass pastures

Throughout January to September 2004 (first year) and 2005 (second year), the effects of 103, 121, 146 and 163-day (first year), and 73, 103, 131 and 163-day (second year) deferring periods, as well as 1, 29, 57 and 85-day grazing on forage production and beef cattle performance in Brachiaria decumbens cv. Basilisk were evaluated. Randomized block design with two replicates, according to the subdivided plots scheme was used. Variation in forage production between the first and second year was observed. Pastures deferred for a longer period had higher total forage mass and dead forage. As the grazing period increased, the total and green forage mass decreased, and the dead forage mass increased. The chemical composition of the forage sample from the grazing simulation was modified by the deferring and grazing periods. The deferring and grazing periods did not affect the supplement intake, expressed as body weight percentage. The bovine performance diminished during the grazing period in the first year (from 0.739 to 0.467 kg/animal.day) and in the second year (from 0.885 to 0.189 kg/animal.day). Pastures deferred for shorter periods in the second year showed higher performance (0.692 kg/animal.day). The weight gain by area was higher on pastures deferred for shorter periods in the second year (4.87 kg/ha.day). In the region of Vicosa, the growing cattle production, kept in deferred pastures, is maximized when pasture fertilized and supplemented by Brachiaria decumbens cv. Basilisk is deferred for about 70 days and used from early July on.

Efeito da adubação nitrogenada e irrigação sobre a composição químico-bromatológica das lâminas foliares e da planta inteira de capim-elefante sob pastejo

This research was carried out to evaluate the chemical composition of elephantgrass cv. Napier in the whole plant (WP) (stem+leaf) and in the leaf blade of non-decapitated basal tillers (SF-NDBT) and leaf blade of decapitated basal tillers (SF-DBT), fertilized with different N doses (100, 200, 300, and 400 kg/ha/year of N) in an irrigated area (IA) and in a non-irrigated area (NIA). Treatments were analyzed in a randomized block design with three replicates. The CP concentrations were proportional to the N doses with greater CP concentration in the rainy season in fractions SF-NDBT and SF-DBT. Fertilizer residues of N doses applied in the rainy season, both in IA and NIA, increased CP concentration in the leaf blade of the two tiller categories, but did not affect NDF and ADF concentration. Irrigation increased concentration of NDF and ADF in SF-NDBT and SF-DBT and reduced it in the WP, with no effect on CP concentration.

Disponibilidade e qualidade do capim-elefante com e sem irrigação adubado com nitrogênio e potássio na estação seca

An experiment was carried out in experimental plots of 300 m2 in size to evaluate the effects of doses of NK fertilization and irrigation on forage mass yield and quality of elephantgras cv Napier during the dry season. The experimental design was completely randomized with three treatment replications. The experimental treatments were arranged in a 4 x 2 factorial combination of four N-K2O doses with and without irrigation, in the dry season. N-K2O doses were: 100-80; 200-160; 300-240 and 400-320 kg.ha-1, respectively. Figures for total dry forage mass (TDFM), and dry green leaf mass (DGLM) increased in proportion to N-K2O dose from May to September 2001, the dry season period. Irrigation had a marked significant effect on DGLM yield. Leaf samples from irrigated plots had higher contents of neutral and acid detergent fiber as compared to leaf samples from the control plots. Concentrations of crude protein, potash, phosphorus, calcium and magnesium did not respond either to N-K2O doses or to irrigation.

Renovação de pastagem degradada de capim-gordura com a introdução de forrageiras tropicais adubadas com nitrogênio ou em consórcios

This study was carried out to evaluate the productivity and quality of either Brachiaria decumbens Stapf. cv. Basilisk and Hyparrhenia rufa (Ness) Stapf. grasses fertilized with nitrogen (N) or mixed with stylosanthes (Stylosanthes guianensis (Aubl.) Swartz cv. Mineirao), introduced into a degraded pasture. Both grasses were evaluated, as well as four doses of nitrogen (0, 50, 100 and 150 kg/ha) and two treatments that consisted of mixing B. decumbens and S. guianensis as well as H. rufa and S. guianensis. [...]Um experimento foi conduzido com objetivo de avaliar a produtividade e qualidade do capim-braquiaria (Brachiaria decumbens Stapf. cv. Basilisk) e do capim-jaragua (Hyparrhenia rufa (Ness) Stapf.) adubados com nitrogenio (N) ou em consorcios com estilosantes (Stylosanthes guianensis (Aubl.) Swartz cv. Mineirao), introduzidos em uma pastagem degradada. Foram avaliadas duas gramineas (capim-braquiaria e capim-jaragua), quatro doses de N (0, 50, 100 e 150 kg/ha) e dois tratamentos referentes aos consorcios capim-braquiaria + estilosantes e capim-jaragua + estilosantes. Apos estabelecimento das forrageiras, foram realizadas duas avaliacoes (colheitas). As producoes de materia seca (MS) do capim-braquiaria aumentaram de 1.824 para 4.604 kg/ha e de 1.019 para 2.149 kg/ha nas duas colheitas, respectivamente, quando as doses de N extremas foram comparadas, porem nao houve resposta do capim-jaragua. O teor de proteina bruta (PB) do capim-braquiaria elevou de 3,18 para 5,68 dag/kg apenas na primeira colheita, enquanto o capim-jaragua apresentou incremento de 2,53 para 3,72 dag/kg e de 7,32 para 8,45 dag/kg, respectivamente, em ambas as colheitas, quando comparadas as doses extremas. Os teores de fibra em detergente neutro (FDN) e fibra em detergente acido das gramineas nao foram influenciados pela aplicacao de N. Em ambas as colheitas, ao se elevarem as doses de N, houve diminuicao dos teores de P nas duas gramineas e de K no capim-braquiaria. Os teores de Ca e Mg das gramineas, em sua maioria, nao foram influenciados pelo N, em ambas as colheitas. As producoes medias de MS dos dois consorcios foram superiores as producoes medias das duas gramineas adubadas, com incrementos de 42,62 e 15,00% no rendimento forrageiro, na primeira e segunda colheitas, respectivamente. As forrageiras em consorcios, de forma geral, apresentaram teores de PB e Ca mais elevados e de FDN mais baixos que as gramineas puras adubadas com N, melhorando a qualidade do pasto.

Rendimento e composição química do capim-braquiária introduzido em pastagem degradada de capim-gordura

An experiment was carried out to evaluate the reclamation of a degraded pasture of molassesgrass (Melinis minutiflora, Beauv.), with the establishment of signalgrass (Brachiaria decumbens, Stapf), with different N doses (0, 50, 100, and 150 kg/ha.year) or in consortium with S. guianensis cv. mineirao, in a complete randomized blocks design, with three replications per treatment. Evaluations were performed during the dry season (one evaluation) and wet season (three evaluations). Nitrogen fertilization promoted increment in dry matter production and crude protein (CP) concentration of signalgrass, in both seasons. There were no effect of neutral detergent fiber and acid detergent fiber concentration of signalgrass in both seasons. Increasing N doses did not alter P, Ca, and Mg concentration neither in the dry nor in the rainy seasons, but it decreased K concentration in both seasons. Signalgrass and Stylosanthes mixture presented low dry matter production in the dry season, being similar to signalgrass without nitrogen fertilizer. During the wet season, however there was no statistical difference between the consortium and treatments with nitrogen fertilization. The consortium, in general, presented greater forage CP concentration compared to signalgrass fertilized with nitrogen.

Estabelecimento de pastagem consorciada com aplicação de calcário, fósforo e gesso

At low fetility soil, in degraded natural pasture, a field trial was carried out at the Federal University of Vicosa, located at Vicosa - MG, was established the pasture of Brachiaria decumbens in mixture with Stylosanthes guianensis cv. Mineirao to evaluate the effect of limestone doses (1.175, 2.350, 3.525 and 4.700 kg/ha, equivalent 25, 50, 75 and 100% of limestone necessity), gypsum doses (0, 230, 940, 1.880 e 2.820 kg/ha equivalent the substitution of 0, 3,0, 12,5, 25,0 and 37,5% of limestone CaO by gypsum CaO) and P2O5 doses (50, 100, 150, 200 and 250 kg/ha) on the pH; availables P, S and K; exchangeables Ca2+, Mg2+, Al3+, H + Al; sum of bases (SB); effetive CEC (t) and CEC determined in pH 7,0 (T); base saturation (V); aluminum saturation (m) and dry matter production, tillers number and height of brachiaria grass and legume percent. The substitution of the limestone CaO by gypsum CaO increased the percent of stylosanthes, available S and Al3+, in 0-15 and 15-30 cm soil layer, and decreased Ca2+ and Mg2+, in 0-15 cm soil layer. The P doses increased the available P (Mehlich 1) in 0-15 cm soil layer, but decreased the legume percent in the pasture.

Absorção e Níveis Críticos de Fósforo na parte aérea para manutenção da produtividade do Capim-Elefante (Pennisetum purpureum cv. Napier)

The experiment was carried out in the field, during two years, to evaluate the phosphate fertilizing residual effect implantation over the phosphate absorption and critical levels in the plant for the elephant grass (Pennisetum purpureum Schum. cv. Napier) maintenance. The treatments were arranged according to the factorial 2 X 2 X 5, in blocks randomly lined with three repetitions, and consisted of two phosphate application ways (located in the bottom of the hole and distributed in the hole with incorporation), two spacing between the plantation lines (0,5 and 1,0 m) and five levels of phosphate correspond to the 0, 30, 60,100 and 150 kg/ha P doses and to 0, 60, 120, 200 and 300 kg/ha of the P2O5 to the applications localized and distributed, respectively. Seven plant harvesting were done from the plants in the parcel central hole (lines), corresponding to 2 m2. After weighing the harvested forage, samples were taken to determinate the dry matter content (DM) and the phosphate in the DM. After each cut, a dressing fertilization with potassium and nitrogen covering (67 kg/ha of N and K2O, using ammonium sulfate and potassium cloret). The highest phosphate content in the plant DM was observed when the fertilizer was distributed and incorporated to the plantation hole. The phosphate critical level in the plants DM presented an average level of 0.13 dag/kg, without great variations due to the application way and, or, to the spacing between the plantation lines.