Feeding behavior of sheep in feedlot and fed with diets containing detoxified castor cake in substitution to the soybean meal

To evaluate the ingestive behavior of sheep confined and fed with substitution levels of soybean meal (SM) by detoxified castor cake (DCC). We adopted a completely randomized design, with four levels of substitution (0; 33; 67 and 100%) with five replicates (sheep). We estimated the percentages of total times of intake of feed, time of rumination, in 'other activities', in idle agreed and in idle sleeping, dividing the day into eight periods (5h00 to 8h00; 8h01 to 11h00; 11h01 to 14h00; 14h01 to 17h00; 17h01 to 20h00; 20h01 to 23h00; 23h01 to 2h00 and 2h01 to 5h00). No interaction was observed between levels of substitution of the SM by DCC and period of the day to go. However, the isolated effect period of the day, there is more time to go from 8h00 to 11h00. The time rumination was not influenced by the levels of substitution of the SM by DCC. As for the variable other activities, the level of 67% DCC was superior to that of 100%. Regarding the variables idle agreed and idle sleeping, were not observed effects of substitution levels of SM by DCC. The DCC provides no changes in the behavior of the sheep, but the period of the day exerts influence on the behavioral pattern of such animals.(AU)

Biomass components and water use efficiency in cactus pear under different irrigation systems and harvest frequencies

The objective was to evaluate the effect of different irrigation systems and harvest frequencies on the cultivation of cactus pear. The study was conducted in the semi-arid region, in the municipality of Russas, CE, Brazil. The experiment was a split plot randomized block design, with four replications. Plots were represented by irrigation systems (surface drip, microsprinkler, Micro Spray Jet, and conventional sprinkler) and subplots by harvest frequencies (6, 9, 12, and 18 months). Cactus pear biomass production characteristics were evaluated. Most of the productive characteristics evaluated were influenced by harvest frequency and irrigation system. The harvest frequency of 12 months combined with conventional sprinkler system resulted in a total dry biomass production of 16,400 kg ha−1. The conventional sprinkler system showed the highest number of second-order cladodes (4.9 cladodes plant−1). The conventional sprinkler and Micro Spray Jet systems showed the highest values for various structural characteristics. For water use efficiency (WUE), the highest value was found at the frequency of six months (8.46 kg ha−1 mm−1). Regarding the effects of irrigation system on WUE, the highest values were observed with the conventional sprinkler system (8.20 kg ha−1 mm−1). The harvest frequency of 12 months combined with the conventional sprinkler system presents better results in the evaluated productive characteristics, mainly the cactus pear production by area.(AU)

Nutritional value of cactus pear grown under different levels of nitrogen and phosphorus and two harvest frequencies

This study evaluated the effects of N/P fertilization on the chemical, mineral composition, and in vitro degradation kinetics of cactus pear cv. Gigante. The research was conducted in Quixadá and Tejuçuoca, CE, Brazil. Nine N/P combinations were evaluated from five levels of N (10, 70, 100, 130, and 190 kg ha−1 year−1), five levels of P2 O5 (10, 70, 100, 130, and 190 kg ha−1 year−1), and two harvest frequencies (annual and biannual). The experiment was performed in a split plot completely randomized block design, with four replications. The maximum CP content was obtained in biannual harvest in Quixadá and Tejuçuoca with the combined levels N/P2 O5 of 190/190 and 130.03/190 kg ha−1 year−1, respectively. Calcium content was reduced by fertilization, which allowed to reduce the Ca:P ratio to 9.72:1.00 with the N/P2 O5 combination at 190/10 kg ha−1 year−1 in the biannual harvest. The increase in N and P levels results in higher S and Mn content and higher digestibility. The annual harvest improves quality in Quixadá. However, it has weaker influence on quality in Tejuçuoca. In Tejuçuoca, Mg, Cu, and Mn contents are lower under annual harvest. Sulfur content is lower under annual harvest in both sites.

Morphophysiology of tropical grasses under different water supply in two growing seasons: II. BRS Massai and BRS Tamani grasses / Morfofisiologia de gramíneas tropicais sob diferentes regimes hídricos em duas estações de crescimento: II. capins BRS Massai e BRS Tamani

This study aimed to evaluate the physiological parameters and the biomass flow and structural characteristics of BRS Massai and BRS Tamani grasses under different irrigation conditions. The rating of gas exchange, biomass flow and structural characteristics were performed in dry periods and dry/rainy season, under the water supply of 30; 60; 90 and 120% of the reference evapotranspiration (ETo). The experimental design was completely randomized in a factorial arrangement 4x2 (water supply and grass). The experiment was conducted in pots with capacity for 7.5 dm³, using as substrate layer of 0-0.2 m soil. There was no effect (P < 0.05) between the gas exchange in the dry period, having the largest growing parameters of irrigation schemes. In the transition period of dry/rainy, we observed a reversal behavior in relation to the dry period, showing a rapid recovery of grasses under the minor water supply. It was observed quadratic behavior to concentrations of CO2 in the leaf mesophilic (Ci) with maximum point to the BRS Massai grass and minimum point to the BRS Tamani grass, where the major and minor Ci were 119 and 48 ppm in the water supply of 107 and 35% of ETo, respectively. In relation to the biomass flow, the BRS Tamani grass presented greater stem elongation rate and leaf senescence rate in relation to BRS Massai in both periods assessed. In the dry period, we observed a higher biomass production of green leaf blades in the BRS Tamani grass, while in the transition dry/rainy season, the results for this variable were similar, and at the same time that observed higher accumulation of green culm biomass to the BRS Tamani grass, which certainly affected its structure. It is concluded that the application of a minimum daily water supply of 30% of ETo allows the maintenance of BRS Massai and BRS Tamani grasses without incurring the death of tillers and reduction of regrowth vigor, whereas the water supply of 90% of ETo favors the morphophysiological characteristics, especially of BRS Tamani grass.(AU)

Objetivou-se avaliar os parâmetros fisiológicos, as características morfogênicas e estruturais dos capins BRS Massai e BRS Tamani sob diferentes condições hídricas. As avaliações de trocas gasosas, do fluxo de biomassa e das características estruturais foram realizadas nos períodos seco e de transição seca/ águas, sob os regimes de lâminas de irrigação de 30; 60; 90 e 120% da evapotranspiração de referência (ETo). Utilizou-se o delineamento inteiramente casualizado em arranjo fatorial 4x2 (lâminas de irrigação e gramíneas). O experimento foi conduzido em vasos com capacidade para 7,5 dm³, utilizando como substrato a camada de 0-0,2 m do solo. Houve efeito (P < 0,05) entre as trocas gasosas no período seco, onde os crescentes regimes de irrigação proporcionaram melhores resultados. No período de transição seco/chuvoso observou-se uma inversão de comportamento em relação ao período seco, evidenciando rápida recuperação das gramíneas sob os menores tratamentos de irrigação. Observou-se comportamento quadrático para variável concentrações de CO2 no mesófilo foliar (Ci), com ponto de máximo para o capimmassai e de mínimo para o capim-tamani, onde as maiores e menores Ci de 119 e 48 ppm nas lâminas de irrigação de 107 e 35% da ETo, respectivamente. No tocante ao fluxo de biomassa, o capim-tamani apresentou maior taxa de alongamento das hastes e de senescência foliar em relação a cultivar BRS Massai em ambos os períodos avaliados. No período seco, observou-se maior produção de biomassa de lâminas foliares verde no capim-tamani, enquanto que no período de transição seca/águas, os resultados para esta variável foram semelhantes, ao mesmo tempo em que se observa maior acúmulo de biomassa de colmo verde no capim-tamani, o que afetou sua estrutura. Conclui-se que a aplicação de uma lâmina mínima diária de 30% da ETo possibilita a manutenção das gramíneas BRS Massai e BRS Tamani sem incorrer em morte de perfilhos e redução do vigor de rebrotação, ao passo que a lâmina de 90% da ETo favorece as características morfofisiológicas, em especial do capim-tamani.(AU)

Forage biomass and water storage of cactus pear under different managements in semi-arid conditions

Forage biomass production and water storage (WS) was evaluated in cactus pear cv. Gigante fertilized with combinations of nitrogen (10, 70, 100, 130, and 190 kg ha−1 yr−1 N) and phosphorus (10, 70, 100, 130, and 190 kg ha−1 yr−1 P2 O5 ) in annual (AH) and biennial (BH) harvest frequencies, in Quixadá and Tejuçuoca, Brazil. A randomized complete block design was used in a split-plot arrangement with four replications. In Quixadá, the maximum total forage biomass (TFB) recorded in the AH was 3,522.9 kg ha−1 yr−1 for the N/P2 O5 combination of 134.6/190.0 kg ha−1 yr−1, and in the BH, the maximum TFB of 1,583.2 kg ha−1 yr−1 was recorded for the N/P2 O5 combination of 114.6/136.8 kg ha−1 yr−1. In Tejuçuoca, the maximum TFB recorded in the AH was 9,783.0 kg ha−1 yr−1 for the N/P2 O5 combination of 137.7/190.0 kg ha−1 yr−1, and in the BH, the maximum TFB of 12,124.0 kg ha−1 yr−1 was recorded for the N/P2 O5 combination of 190.0/56.8 kg ha−1 yr−1. In Quixadá, the maximum WS recorded in the AH was 39.1 kg ha−1 mm−1 for the N/P2 O5 combination of 161.0/190.0 kg ha−1 yr−1, and in the BH, the maximum WS of 11.3 kg ha−1 mm−1 was recorded for the N/P2 O5 combination of 113.5/158.7 kg ha−1 yr−1. In Tejuçuoca, the maximum WS recorded in the AH was 196.1 kg ha−1 mm−1 for the N/P2 O5 combination of 190.0/190.0 kg ha−1 yr−1, and in the BH, the maximum WS of 265.5 kg ha−1 mm−1 was recorded for the N/P2 O5 combination of 190.0/10.0 kg ha−1 yr−1. To achieve the persistence and longevity of the cactus pear cv. Gigante, the management with BH and fertilization with the N/P2 O5 combination of 114.6/136.8 kg ha−1 yr−1 (in regions similar to Quixadá) and N/P2 O5 combination of 190.0/56.8 kg ha−1 yr−1 (in regions similar to Tejuçuoca) is recommended.

Photochemical activity modulated by water, nitrogen, and phosphorus status in cactus pear

This study aimed to evaluate the effects of nitrogen (N) and phosphorus (P) associated with dry and rainy seasons on the photochemical activity of Opuntia ficus-indica (L.) Mill. cv. Gigante. Combinations of N (10.0, 70.0, 100.0, 130.0, and 190.0 kg ha−1 yr−1) and P2 O5 (10.0, 70.0, 100.0, 130.0, and 190.0 kg ha−1 yr−1) were evaluated in the dry and rainy seasons in semi-arid regions. A completely randomized block design with split-plot arrangement was adopted with four replications. In Quixadá, the maximum potential quantum efficiency of photosystem II (Fv/Fm) was 0.82, observed in third-order cladodes (rainy season and N/P 75.6/10.0 kg ha−1 yr−1), while in Tejuçuoca, the maximum Fv/Fm was 0.81, found in 2nd/3rd order cladodes (rainy season and N/P 10.0/190.0 kg ha−1 yr−1). In Quixadá, the maximum electron transport rate (ETR) was 31.6 µmol m−2 s−1 in 2nd/3rd order cladodes (rainy season and N/P 10.0/190.0 kg ha−1 yr−1), and in Tejuçuoca, the maximum ETR was 24.1 µmol m−2 s−1, in second-order cladodes (rainy season and N/P 110.1/10.0 kg ha−1 yr−1). In Quixadá and Tejuçuoca, higher values of Fv/Fm and ETR were observed in the rainy season. In Quixadá, the maximum fluorescence decrease ratio (FDR) was 4.04 in third-order cladodes (rainy season and N/P 10.0/114.8 kg ha−1 yr−1), while in Tejuçuoca, the maximum FDR was 6.93, found in 2nd/3rd order cladodes (rainy season and N/P 190.0/10.0 kg ha−1 yr−1). In Quixadá and Tejuçuoca, there was predominance of higher FDR values in the rainy season. Nitrogen, phosphorus, and water status modulate the photochemical efficiency of cladodes of cactus pear cv. Gigante in semi-arid regions.

Growth indexes of Pennisetum purpureum cv. Roxo cultivated in different seasons under rainfed conditions / Índices de crescimento do Pennisetum purpureum cv. Roxo cultivado em diferentes épocas sob regime de sequeiro

The objective was to estimate the growth indexes of elephant grass cv. Roxo managed under rainfed conditions in different growing seasons. Seven growth ages (9, 18, 27, 36, 45, 54, and 63 days) were evaluated in three growing seasons (rainy, transition and dry). A completely randomised design was adopted, with split-plot arrangement with time repeated measures, with the ages being the plots and the seasons the subplots. Interaction of age x season was observed. The specific leaf area mean was 0.0286 ± 0.0039 during the rainy season. In the transition season, it adjusted to a third-degree polynomial model; in the dry season it declined linearly (0.0003 m2 g-1). The leaf weight ratio adjusted to the third-degree polynomial model in the rainy and dry seasons, and in the transition season it was maximised at 28 DAC (0.694 g g-1). The leaf area ratio continuously declined in the rainy season. In the transition and dry seasons, it adjusted to the third-degree polynomial model. The net assimilation rate presented averages of 3.73 ± 2.50 and 3.63 ± 1.48 g m-2 day-1 in the rainy and transition seasons, respectively. In the dry season, it was minimised at 48.4 days. The relative growth rate mean was 0.0075 ± 0.0037 during the rainy season. In the transition and dry seasons, it adjusted to the third-degree polynomial model. The growth index rates of elephant grass cv. Roxo are modified by growing seasons, and the pattern and magnitude of the response varies throughout the growth cycle.(AU)

Objetivou-se estimar os índices de crescimento do capim-elefante cv. Roxo manejado sob sequeiro em diferentes épocas de cultivo. Analisaram-se sete idades de crescimento (9; 18; 27; 36; 45; 54 e 63 dias) em três épocas de cultivo (chuvosa, transição e seca). Adotou-se delineamento inteiramente casualizado em arranjo de parcelas subdivididas no tempo, com as idades sendo alocadas nas parcelas e as épocas de cultivo nas subparcelas. Constatou-se interação idade x época de cultivo. A área foliar específica revelou média de 0,0286 ± 0,0039 na época chuvosa. Na época de transição ajustou-se ao modelo polinomial de terceiro grau e na época seca reduziu linearmente (0,0003 m2 g-1). A razão de peso foliar ajustou-se ao modelo polinomial de terceiro grau nas épocas chuvosa e seca e na época de transição foi maximizada aos 28 DAC (0,694 g g-1). A razão de área foliar reduziu continuamente na época chuvosa. Já nas épocas de transição e seca ajustou-se ao modelo polinomial de terceiro grau. A taxa de assimilação líquida apresentou médias de 3,73 ± 2,50 e 3,63 ± 1,48 g m-2 dia-1 para as épocas chuvosa e de transição, respectivamente. Na época seca, foi minimizada aos 48,4 dias. A taxa de crescimento relativo apresentou média de 0,0075 ± 0,0037 na época chuvosa. Nas épocas de transição e seca ajustou-se ao modelo polinomial de terceiro grau. Os índices de crescimento do capim-elefante cv. Roxo são modificados pelas épocas de cultivo e o padrão e a magnitude da resposta variam ao longo do ciclo de crescimento.(AU)

Growth indexes of Pennisetum purpureum cv. Roxo cultivated in different seasons under rainfed conditions / Índices de crescimento do Pennisetum purpureum cv. Roxo cultivado em diferentes épocas sob regime de sequeiro

The objective was to estimate the growth indexes of elephant grass cv. Roxo managed under rainfed conditions in different growing seasons. Seven growth ages (9, 18, 27, 36, 45, 54, and 63 days) were evaluated in three growing seasons (rainy, transition and dry). A completely randomised design was adopted, with split-plot arrangement with time repeated measures, with the ages being the plots and the seasons the subplots. Interaction of age x season was observed. The specific leaf area mean was 0.0286 ± 0.0039 during the rainy season. In the transition season, it adjusted to a third-degree polynomial model; in the dry season it declined linearly (0.0003 m2 g-1). The leaf weight ratio adjusted to the third-degree polynomial model in the rainy and dry seasons, and in the transition season it was maximised at 28 DAC (0.694 g g-1). The leaf area ratio continuously declined in the rainy season. In the transition and dry seasons, it adjusted to the third-degree polynomial model. The net assimilation rate presented averages of 3.73 ± 2.50 and 3.63 ± 1.48 g m-2 day-1 in the rainy and transition seasons, respectively. In the dry season, it was minimised at 48.4 days. The relative growth rate mean was 0.0075 ± 0.0037 during the rainy season. In the transition and dry seasons, it adjusted to the third-degree polynomial model. The growth index rates of elephant grass cv. Roxo are modified by growing seasons, and the pattern and magnitude of the response varies throughout the growth cycle.

Objetivou-se estimar os índices de crescimento do capim-elefante cv. Roxo manejado sob sequeiro em diferentes épocas de cultivo. Analisaram-se sete idades de crescimento (9; 18; 27; 36; 45; 54 e 63 dias) em três épocas de cultivo (chuvosa, transição e seca). Adotou-se delineamento inteiramente casualizado em arranjo de parcelas subdivididas no tempo, com as idades sendo alocadas nas parcelas e as épocas de cultivo nas subparcelas. Constatou-se interação idade x época de cultivo. A área foliar específica revelou média de 0,0286 ± 0,0039 na época chuvosa. Na época de transição ajustou-se ao modelo polinomial de terceiro grau e na época seca reduziu linearmente (0,0003 m2 g-1). A razão de peso foliar ajustou-se ao modelo polinomial de terceiro grau nas épocas chuvosa e seca e na época de transição foi maximizada aos 28 DAC (0,694 g g-1). A razão de área foliar reduziu continuamente na época chuvosa. Já nas épocas de transição e seca ajustou-se ao modelo polinomial de terceiro grau. A taxa de assimilação líquida apresentou médias de 3,73 ± 2,50 e 3,63 ± 1,48 g m-2 dia-1 para as épocas chuvosa e de transição, respectivamente. Na época seca, foi minimizada aos 48,4 dias. A taxa de crescimento relativo apresentou média de 0,0075 ± 0,0037 na época chuvosa. Nas épocas de transição e seca ajustou-se ao modelo polinomial de terceiro grau. Os índices de crescimento do capim-elefante cv. Roxo são modificados pelas épocas de cultivo e o padrão e a magnitude da resposta variam ao longo do ciclo de crescimento.

Biomass components of Pennisetum purpureum cv. Roxo managed at different growth ages and seasons / Componentes da biomassa em “Pennisetum purpureum” cv. Roxo manejado sob diferentes idades e épocas de crescimento

This study was carried out aiming to evaluate the biomass components of elephant grass cv. Roxo at seven growth ages, during rainy, transition and dry seasons. A completely randomized design was adopted with a split plot arrangement over time. The treatments consisted of seven growth ages (9, 18, 27, 36, 45, 54 and 63) and three seasons (rainy, transition and dry). The variables green forage biomass, dead forage biomass, green stem biomass and green leaf blade biomass showed positive linear responses to age and had their magnitude influenced by the evaluated seasons. The live/dead material ratio showed a decreasing linear response as a function of age. The leaf blade/stem ratio showed a negative linear adjustment in the rainy season, reaching a critical value of 1.0 at 59 days, and it showed a quadratic adjustment in the transition season, with the maximum point at 27.53 days; however, this ratio was not influenced by age in the dry season, revealing an average value of 2.22 ± 0.27. The canopy height and leaf area index showed a positive linear response to age in the three seasons. Tiller population density showed quadratic behaviour for age, with maximum estimated values of 134 and 110 til. m-2 at 31.24 and 37.40 days in the rainy and dry seasons, respectively. Rainfall seasonality influences the magnitude of the daily increase of the distinct biomass components of Pennisetum purpureum cv. Roxo.(AU)

Objetivou-se avaliar os componentes da biomassa em capim-elefante cv. Roxo em sete idades de crescimento, nas épocas chuvosa, transição e seca. Adotou-se um delineamento inteiramente casualizado, em arranjo de parcelas subdivididas no tempo. Os tratamentos consistiram em sete idades de crescimentos (9; 18; 27; 36; 45; 54 e 63 dias) e três épocas (chuvosa, transição e seca). As variáveis biomassa de forragem verde, forragem morta, colmo verde e de lâmina foliar verde apresentaram resposta linear positiva para o fator idade e tiveram suas magnitudes influenciadas pelas épocas de avaliação. A relação material vivo/material morto respondeu de forma linear decrescente em função das idades. A relação lâmina foliar/colmo apresentou ajuste linear negativo na época chuvosa, atingindo valor crítico de 1,0 aos 59 dias e ajuste quadrático na época de transição, com ponto de máxima aos 27,53 dias, e não foi influenciada pelo fator idade na época seca, com valor médio de 2,22±0,27. A altura do dossel e o índice de área foliar responderam de forma linear positiva para o fator idade, nas três épocas. A densidade populacional de perfilhos apresentou comportamento quadrático para o fator idade, com valores máximos estimados em 134 e 110 perf. m-2 aos 31,24 e 37,40 dias de idade nas épocas chuvosa e seca, respectivamente. A sazonalidade da precipitação pluvial influencia a magnitude do incremento diário nos distintos componentes da biomassa em Pennisetum purpureum cv. Roxo.(AU)

Accumulation and partition of macronutrients in Pennisetum purpureum cv. Roxo managed under different growth ages and seasons / Acúmulo e partição de macronutrientes em “Pennisetum purpureum ” cv. Roxo manejado em diferentes idades e épocas de crescimento

The objective of this study was to evaluate the macronutrient accumulations in leaf, stem, and shoot of elephant grass cv. Roxo. The treatments consisted of seven growth ages (9, 18, 27, 36, 45, 54, and 63 days) and three growing seasons (rainy, transition, and dry). A completely randomized design and a split-plot time arrangement were used, where the ages were the plots and the seasons the subplots, with three replications. Interaction between the factors age and season of cultivation for the contents and the daily accumulation rates of N, P, K, Ca, Mg, and S in leaf, stem, and shoot fractions were calculated. The margins of daily accumulation of nutrients N, P, K, Mg, and S presented positive linear behavior in all seasons studied; however, with variation in the magnitude of the response between them. The daily accumulation rate of Ca in the canopy was adjusted to a linear model for the rainy and dry seasons and to a quadratic model for the transition season, reaching a maximum of 4.60 kg ha-1 at 59.76 days of growth. The accumulation of nutrients in elephant grass cv. Roxo showed the following decreasing order: K > N > P > Mg > Ca > S in the rainy and transition seasons, while in the dry season the following decreasing order was observed: K > P > N > Ca > Mg > S.(AU)

Objetivou-se avaliar a marcha de acúmulo de macronutrientes na folha, colmo e na parte aérea do capim-elefante cv. Roxo. Os tratamentos consistiram em sete idades de crescimento (9; 18; 27; 36; 45; 54 e 63 dias) em três períodos de cultivo (chuvoso, de transição e seco). Adotou-se um delineamento inteiramente casualizado e um arranjo de parcelas subdivididas no tempo, onde as idades foram alocadas nas parcelas e os períodos de cultivo nas subparcelas, com três repetições. Constatou-se interação entre os fatores idade e período de cultivo para os teores e para as taxas de acúmulo diário de N, P, K, Ca, Mg e S nas frações folha, colmo e parte aérea. As marchas de acúmulo diário dos nutrientes N, P, K, Mg e S apresentaram comportamento linear positivo para todos os períodos estudados, todavia com variação na magnitude da resposta entre estes. A taxa de acúmulo diário de Ca na parte aérea do dossel ajustou-se ao modelo linear para os períodos chuvoso e seco e ao modelo quadrático para o período de transição, atingindo máximo de 4,60 kg ha-1 aos 59,76 dias de crescimento. O acúmulo dos nutrientes no capim-elefante cv. Roxo apresentou a seguinte ordem decrescente: K > N > P > Mg > Ca > S no período chuvoso e de transição enquanto no período seco observou-se a seguinte ordem decrescente: K > P > N > Ca > Mg> S.(AU)

Biomass components of Pennisetum purpureum cv. Roxo managed at different growth ages and seasons / Componentes da biomassa em “Pennisetum purpureum” cv. Roxo manejado sob diferentes idades e épocas de crescimento

This study was carried out aiming to evaluate the biomass components of elephant grass cv. Roxo at seven growth ages, during rainy, transition and dry seasons. A completely randomized design was adopted with a split plot arrangement over time. The treatments consisted of seven growth ages (9, 18, 27, 36, 45, 54 and 63) and three seasons (rainy, transition and dry). The variables green forage biomass, dead forage biomass, green stem biomass and green leaf blade biomass showed positive linear responses to age and had their magnitude influenced by the evaluated seasons. The live/dead material ratio showed a decreasing linear response as a function of age. The leaf blade/stem ratio showed a negative linear adjustment in the rainy season, reaching a critical value of 1.0 at 59 days, and it showed a quadratic adjustment in the transition season, with the maximum point at 27.53 days; however, this ratio was not influenced by age in the dry season, revealing an average value of 2.22 ± 0.27. The canopy height and leaf area index showed a positive linear response to age in the three seasons. Tiller population density showed quadratic behaviour for age, with maximum estimated values of 134 and 110 til. m-2 at 31.24 and 37.40 days in the rainy and dry seasons, respectively. Rainfall seasonality influences the magnitude of the daily increase of the distinct biomass components of Pennisetum purpureum cv. Roxo.

Objetivou-se avaliar os componentes da biomassa em capim-elefante cv. Roxo em sete idades de crescimento, nas épocas chuvosa, transição e seca. Adotou-se um delineamento inteiramente casualizado, em arranjo de parcelas subdivididas no tempo. Os tratamentos consistiram em sete idades de crescimentos (9; 18; 27; 36; 45; 54 e 63 dias) e três épocas (chuvosa, transição e seca). As variáveis biomassa de forragem verde, forragem morta, colmo verde e de lâmina foliar verde apresentaram resposta linear positiva para o fator idade e tiveram suas magnitudes influenciadas pelas épocas de avaliação. A relação material vivo/material morto respondeu de forma linear decrescente em função das idades. A relação lâmina foliar/colmo apresentou ajuste linear negativo na época chuvosa, atingindo valor crítico de 1,0 aos 59 dias e ajuste quadrático na época de transição, com ponto de máxima aos 27,53 dias, e não foi influenciada pelo fator idade na época seca, com valor médio de 2,22±0,27. A altura do dossel e o índice de área foliar responderam de forma linear positiva para o fator idade, nas três épocas. A densidade populacional de perfilhos apresentou comportamento quadrático para o fator idade, com valores máximos estimados em 134 e 110 perf. m-2 aos 31,24 e 37,40 dias de idade nas épocas chuvosa e seca, respectivamente. A sazonalidade da precipitação pluvial influencia a magnitude do incremento diário nos distintos componentes da biomassa em Pennisetum purpureum cv. Roxo.

Accumulation and partition of macronutrients in Pennisetum purpureum cv. Roxo managed under different growth ages and seasons / Acúmulo e partição de macronutrientes em “Pennisetum purpureum ” cv. Roxo manejado em diferentes idades e épocas de crescimento

The objective of this study was to evaluate the macronutrient accumulations in leaf, stem, and shoot of elephant grass cv. Roxo. The treatments consisted of seven growth ages (9, 18, 27, 36, 45, 54, and 63 days) and three growing seasons (rainy, transition, and dry). A completely randomized design and a split-plot time arrangement were used, where the ages were the plots and the seasons the subplots, with three replications. Interaction between the factors age and season of cultivation for the contents and the daily accumulation rates of N, P, K, Ca, Mg, and S in leaf, stem, and shoot fractions were calculated. The margins of daily accumulation of nutrients N, P, K, Mg, and S presented positive linear behavior in all seasons studied; however, with variation in the magnitude of the response between them. The daily accumulation rate of Ca in the canopy was adjusted to a linear model for the rainy and dry seasons and to a quadratic model for the transition season, reaching a maximum of 4.60 kg ha-1 at 59.76 days of growth. The accumulation of nutrients in elephant grass cv. Roxo showed the following decreasing order: K > N > P > Mg > Ca > S in the rainy and transition seasons, while in the dry season the following decreasing order was observed: K > P > N > Ca > Mg > S.

Objetivou-se avaliar a marcha de acúmulo de macronutrientes na folha, colmo e na parte aérea do capim-elefante cv. Roxo. Os tratamentos consistiram em sete idades de crescimento (9; 18; 27; 36; 45; 54 e 63 dias) em três períodos de cultivo (chuvoso, de transição e seco). Adotou-se um delineamento inteiramente casualizado e um arranjo de parcelas subdivididas no tempo, onde as idades foram alocadas nas parcelas e os períodos de cultivo nas subparcelas, com três repetições. Constatou-se interação entre os fatores idade e período de cultivo para os teores e para as taxas de acúmulo diário de N, P, K, Ca, Mg e S nas frações folha, colmo e parte aérea. As marchas de acúmulo diário dos nutrientes N, P, K, Mg e S apresentaram comportamento linear positivo para todos os períodos estudados, todavia com variação na magnitude da resposta entre estes. A taxa de acúmulo diário de Ca na parte aérea do dossel ajustou-se ao modelo linear para os períodos chuvoso e seco e ao modelo quadrático para o período de transição, atingindo máximo de 4,60 kg ha-1 aos 59,76 dias de crescimento. O acúmulo dos nutrientes no capim-elefante cv. Roxo apresentou a seguinte ordem decrescente: K > N > P > Mg > Ca > S no período chuvoso e de transição enquanto no período seco observou-se a seguinte ordem decrescente: K > P > N > Ca > Mg> S.

Trocas gasosas e morfofisiologia em capim-massai sob pastejo e adubado com nitrogênio

Objetivou-se avaliar as trocas gasosas, o fluxo de biomassa, a estrutura e os componentes da biomassa no pré e pós-pastejo e a dinâmica de perfilhamento em capim-massai submetido a crescentes doses de nitrogênio (controle - sem nitrogênio; 400; 800 e 1200 kg•ha-1•ano-1) e sob lotação rotativa com ovinos, num delineamento inteiramente casualizado com medidas repetidas no tempo. A dose de nitrogênio para cada tratamento foi dividida em duas parcelas, sendo a primeira metade aplicada logo após a saída dos animais do piquete e a segunda metade aplicada na metade do período de descanso, de acordo com cada dose avaliada. O período de descanso adotado foi de aproximadamente 1,5 novas folhas por perfilho, conforme determinação em pré-ensaio quando do início da instalação do experimento, propiciando um intervalo de 22; 18; 16 e 13 dias para as doses de nitrogênio de 0,0 – controle; 400; 800 e 1200 kg•ha-1•ano-1, respectivamente. A técnica de “mob-grazing” foi usada para a realização dos pastejos, empregando-se grupos de animais para desfolhações rápidas (duração de 7 a 11 horas). À medida que os animais pastejavam, a altura do pasto foi monitorada com auxílio de uma régua, até que o dossel atingisse a altura residual preconizada de aproximadamente 15 cm, correspondendo ao IAF residual de saída dos animais do piquete de aproximadamente 1,5. As variáveis: condutância estomática, taxa de fotossíntese foliar, concentração interna de CO2, relação fotossíntese/transpiração, índice relativo de clorofila e índice de suficiência de nitrogênio responderam de forma linear crescente ao incremento nas doses de nitrogênio...Os ciclos de pastejomodificam as características morfofisiológicas da referidaforrageira em pequena magnitude,quando se adota um manejo rigoroso do pastejo.

To evaluate the gas exchange, the biomass flow, the biomass components before and after grazing and the tillering dynamics in massai grass under increasing nitrogen fertilization levels (control - without nitrogen fertilizer; 400; 800 and 1200 kg•ha-1•year-1) under rotational stocking with sheeps in a completely randomized design with measurements repeated in time, this research was carried out. The level of nitrogen for each treatment was divided into two parcels, the first half applied immediately after the animals leave the paddock and the second half applied in rest period half, according to ea ch level assessed. The rest period was set at approximately 1.5 new leaf blades per tiller, as determined in pre-testing when the starting of the experiment, providing a period of 22, 18, 16 and 13 days for the nitrogen levels of 0.0 - control, 400, 800 and 1200 kg•ha-1•year-1, respectively. The technique of "mob-grazing" was used for the realization of grazing, usi ng groups of animals for rapid defoliation (duration from 7 to 11 hours). With the animals grazing, the sward height was monitored with a ruler until they reach the recommended residual canopy height of approximately 15 cm, corresponding to the residual LAI of approximately 1.5. The variables: stomatal conductance, leaf photosynthesis rate, leaf carbon dioxide concentration, photosynthesis/transpiration ratio, chlorophyll relative index and nitr ogen sufficiency index revealed positive linear response to the nitrogen fertilization... The grazing cycles promote little hanges in the morphophysiological traits of assai grass, when a rigorous grazing management is adopted.

Trocas gasosas e morfofisiologia em capim-massai sob pastejo e adubado com nitrogênio

Objetivou-se avaliar as trocas gasosas, o fluxo de biomassa, a estrutura e os componentes da biomassa no pré e pós-pastejo e a dinâmica de perfilhamento em capim-massai submetido a crescentes doses de nitrogênio (controle - sem nitrogênio; 400; 800 e 1200 kg•ha-1•ano-1) e sob lotação rotativa com ovinos, num delineamento inteiramente casualizado com medidas repetidas no tempo. A dose de nitrogênio para cada tratamento foi dividida em duas parcelas, sendo a primeira metade aplicada logo após a saída dos animais do piquete e a segunda metade aplicada na metade do período de descanso, de acordo com cada dose avaliada. O período de descanso adotado foi de aproximadamente 1,5 novas folhas por perfilho, conforme determinação em pré-ensaio quando do início da instalação do experimento, propiciando um intervalo de 22; 18; 16 e 13 dias para as doses de nitrogênio de 0,0 controle; 400; 800 e 1200 kg•ha-1•ano-1, respectivamente. A técnica de “mob-grazing” foi usada para a realização dos pastejos, empregando-se grupos de animais para desfolhações rápidas (duração de 7 a 11 horas). À medida que os animais pastejavam, a altura do pasto foi monitorada com auxílio de uma régua, até que o dossel atingisse a altura residual preconizada de aproximadamente 15 cm, correspondendo ao IAF residual de saída dos animais do piquete de aproximadamente 1,5. As variáveis: condutância estomática, taxa de fotossíntese foliar, concentração interna de CO2, relação fotossíntese/transpiração, índice relativo de clorofila e índice de suficiência de nitrogênio responderam de forma linear crescente ao incremento nas doses de nitrogênio...Os ciclos de pastejomodificam as características morfofisiológicas da referidaforrageira em pequena magnitude,quando se adota um manejo rigoroso do pastejo.(AU)

To evaluate the gas exchange, the biomass flow, the biomass components before and after grazing and the tillering dynamics in massai grass under increasing nitrogen fertilization levels (control - without nitrogen fertilizer; 400; 800 and 1200 kg•ha-1•year-1) under rotational stocking with sheeps in a completely randomized design with measurements repeated in time, this research was carried out. The level of nitrogen for each treatment was divided into two parcels, the first half applied immediately after the animals leave the paddock and the second half applied in rest period half, according to ea ch level assessed. The rest period was set at approximately 1.5 new leaf blades per tiller, as determined in pre-testing when the starting of the experiment, providing a period of 22, 18, 16 and 13 days for the nitrogen levels of 0.0 - control, 400, 800 and 1200 kg•ha-1•year-1, respectively. The technique of "mob-grazing" was used for the realization of grazing, usi ng groups of animals for rapid defoliation (duration from 7 to 11 hours). With the animals grazing, the sward height was monitored with a ruler until they reach the recommended residual canopy height of approximately 15 cm, corresponding to the residual LAI of approximately 1.5. The variables: stomatal conductance, leaf photosynthesis rate, leaf carbon dioxide concentration, photosynthesis/transpiration ratio, chlorophyll relative index and nitr ogen sufficiency index revealed positive linear response to the nitrogen fertilization... The grazing cycles promote little hanges in the morphophysiological traits of assai grass, when a rigorous grazing management is adopted.(AU)