ABSTRACT The objective was to evaluate the effect of intensifying dairy systems on the uptake and return of nutrients in pastures. The experiment was conducted using four milk production systems on Mombasa grass pastures in the humid tropics, during the rainy season in 2009. This was a 2 x 2 factorial (two nitrogen fertilization levels and concentrate supplement or not for grazing animals) completely randomized design with four replications (paddocks). Nitrogen levels corresponded to 400 and 800 kg. ha-1.year-1, and supplementation was given to only two out of four groups of animals with milk yield above 11 L. day-1. Pastures fertilized with the highest nitrogen level had higher contents of macronutrients in plant tissues and the litter but resulted in lower concentrations of N and Ca in feces. The uptake of macronutrients per grazing cycle was also higher in these pastures. The supplementation caused a decreasing effect on the content of N in dead pasture material, P in litter, and Ca, Mg, and P in feces. Decomposing litter represents the main source of nutrient return to the pasture, especially calcium, phosphorus, and nitrogen. tropics 2009 paddocks. paddocks . (paddocks) 40 80 kg ha1.year1, ha1year1 hayear ha 1.year 1, 1 year ha-1.year-1 L day1. day1 day 1. day-1 feces material Mg calcium phosphorus 200 (paddocks 4 8 ha1 year1 ha1.year1 ha1year 1year ha-1.year- day- 20 ha1.year ha-1.year

ABSTRACT Livestock production in semi-arid areas has been unpredictable due to climate variability, mainly rainfall. This study aims to simulate rangeland production variability affected by rainfall over time and relate it to an adjusted carrying capacity, using forage stock to maximize the potential of production of the system to a specifi c guarantee level. Regression analysis of forage biomass against rainfall was performed for ecological sites in the Brazilian semi-arid region to generate probability distribution curves for the historical rainfall for each location using Monte Carlo approach. Forage biomass variability estimated over time was used as input to the model. The system optimizes forage use at a sustainable stocking rate and uses forage surpluses in good years to fill defi cits during adverse years, due to a certain level of guarantee. As a rule, smallholder farmers would need to maintain a storage of around 1,500 kg ha-1 of DM of forage to maintain an adjusted carrying capacity of 0.11 animal units ha-1, with a guarantee of 95% in the long term, stressing the forage storage capacity as a central component of the model. Since farm size infl uences forage production capacity and mainly forage stock capacity, recommendations to cope with this paradigm are suggested. semiarid semi arid approach model rule 1500 1 500 1,50 ha1 ha ha- 011 0 11 0.1 ha1, 1, 95 term suggested 150 50 1,5 01 0. 9 15 5

ABSTRACT 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 P2O5) 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/P2O5 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/P2O5 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/P2O5 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/P2O5 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/P2O5 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/P2O5 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/P2O5 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/P2O5 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/P2O5 combination of 114.6/136.8 kg ha−1 yr−1 (in regions similar to Quixadá) and N/P2O5 combination of 190.0/56.8 kg ha−1 yr−1 (in regions similar to Tejuçuoca) is recommended.

ABSTRACT 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 P2O5 (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.

RESUMO A adubação balanceada é fator de importância comprovada na otimização do crescimento e produtividade das culturas. Objetivou-se avaliar o fluxo de biomassa e a eficiência de uso da chuva na palma forrageira cv. Gigante, adubada com combinações de doses de nitrogênio (10; 70; 100; 130 e 190 kg ha-1 ano-1 de N) e fósforo (10; 70; 100; 130 e 190 kg ha-1 ano-1 de P2O5), nas frequências de colheita anual e bianual, nas regiões de Quixadá e Tejuçuoca, no Ceará. Utilizou-se delineamento em blocos casualizados, em arranjo de parcelas subdivididas, com quatro repetições. Em Quixadá e Tejuçuoca, as combinações de N e P e frequências de colheita influenciaram as taxas de produções de diferentes ordens de cladódios e a eficiência de uso da chuva na palma forrageira. Em Quixadá, na colheita anual, verificou-se taxa de produção de forragem (TPF) de 10,3 kg ha-1 dia-1 na combinação N/P2O5 de 190,0/190,0 kg ha-1 ano-1 e na colheita bianual, observou-se máxima TPF de 4,6 kg ha-1 dia-1 na combinação N/P2O5 de 114,6/136,8 kg ha-1 ano-1. Em Tejuçuoca, na colheita anual, constatou-se máxima TPF de 30,0 kg ha-1 dia-1 na combinação N/P2O5 de 137,5/190,0 kg ha-1 ano-1 e na colheita bianual, registrou-se maior TPF de 38,0 kg ha-1 dia-1 na combinação N/P2O5 de 190,0/33,4 kg ha-1 ano-1. As taxas de produções de biomassa e eficiência de uso da chuva são otimizadas com o balanço de doses combinadas de nitrogênio e fósforo.

ABSTRACT Balanced fertilization is an important factor in optimizing the growth and productivity of crops. This study aimed to evaluate biomass flow and rain use efficiency in cactus pear cv. Gigante fertilized with combinations of nitrogen (10; 70; 100; 130 and 190 kg ha-1 year-1 N) and phosphorus (10; 70; 100; 130 and 190 kg ha-1 year-1 P2O5), in two harvest frequencies (annual and biennal), in the regions of Quixadá and Tejuçuoca, in Ceará. This was a split-plot randomized block design, with four replicates. In Quixadá and Tejuçuoca, the N and P combinations and harvest frequencies influenced the productions rates of different cladode orders and rain use efficiency in cactus pear. In Quixadá, in the annual harvest, the forage production rate (FPR) was 10.3 kg ha-1 day-1 in the N/P2O5 combination at 190.0/190.0 kg ha-1 year-1 and in the biennal harvest, the maximum FPR was 4.6 kg ha-1 day-1 in the N/P2O5 combination at 114.6/136.8 kg ha-1 year-1. In relation to the annual harvest in the municipality of Tejuçuoca, the maximum FPR was 30.0 kg ha-1 day-1 in the N/P2O5 combination at 137.5/190.0 kg ha-1 year-1 and in the biennal harvest, the maximum FPR observed was 38.0 kg ha-1 day-1 with the N/P2O5 combination of 190.0/33.4 kg ha-1 year-1. The biomass productions rate and rain use efficiency are optimized with the balance of combined levels of nitrogen and phosphorus.

ABSTRACT The present study evaluated the accumulation and export of nutrients in cactus pear (Opuntia ficus-indica) cv. Gigante, fertilized with combinations of nitrogen (10, 70, 100, 130, and 190 kg ha−1 year−1 N) and phosphorus (10, 70, 100, 130, and 190 kg ha−1 year−1 P2O5) under annual and biennial harvests, in Quixadá and Tejuçuoca, using a split-plot randomized block design with four replications. In Quixadá, under annual and biennial harvests, the following orders of accumulation of macronutrients (in kg ha−1 year−1) were found, respectively: K (98.8) > Ca (87.2) > N (46.7) > Mg (26.8) > S (18.4) > P (2.04) and Ca (33.5) > K (31.1) > S (18.6) > N (12.9) > Mg (10.5) > P (0.81). In Tejuçuoca, under annual and biennial harvests, the orders of accumulation of macronutrients were, respectively: K (146.5) > Ca (204.6) > N (128.1) > Mg (75.8) > S (50.3) > P (3.7) and K (397.2) > N (191.3) > S (241.2) > Ca (167.8) > Mg (131.0) > P (14.1). The maintenance/production fertilization in cactus pear should be planned according to productive potential, fertilization and harvest managements, and cultivation region, based on nutritional requirement and considering the nutrient recovery efficiency.

A produção de biomassa em uma pastagem pode ser incrementada com o uso de fertilizantes, principalmente os nitrogenados. Diante disso, objetivou-se, com este trabalho, avaliar o fluxo de biomassa do capim-massai, durante o estabelecimento e a rebrotação, em casa de vegetação, sob cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg de N dm-3 de solo), em delineamento inteiramente casualizado, com medidas repetidas no tempo, e cinco repetições. A taxa de alongamento foliar foi incrementada pelas doses de nitrogênio (N) e o crescimento de estabelecimento apresentou maior valor, em relação ao das rebrotações. A taxa de alongamento das hastes não foi influenciada pelas doses de N. O crescimento de estabelecimento apresentou maior valor para esta variável, em relação ao das rebrotações. A taxa de senescência foliar anterior não sofreu influência das doses de N, porém, foi alterada entre os ciclos de crescimento. O número de folhas vivas por perfilho foi superior, para as maiores doses e no estabelecimento, o inverso ocorrendo para o filocrono. A dose aplicada de 600 mg dm-3 de N proporcionou um incremento de 448%, na taxa de produção de forragem, e de 455%, na taxa de acúmulo de forragem, em relação àquelas do manejo sem N. A adubação nitrogenada proporciona respostas positivas nas variáveis do fluxo de biomassa do capim-massai.

The use of fertilizers, especially nitrogen, can increase significantly the biomass production of a pasture. The objective of this study was to evaluate the biomass flow of Massai grass produced in greenhouse during the establishment and regrowth under five nitrogen fertilization levels. The experiment was arranged in a completely randomized split-plot design with five nitrogen levels (0; 150; 300; 450 e 600 mg de N dm-3 of soil) and five replications (plots) .The leaf elongation rate was increased with the nitrogen fertilization levels and the establishment growth presented higher values in relation to the regrowth. The culm elongation rate was not influenced by N levels. The establishment growth presented higher values than regrowth. The leaf senescence rate before the cut was not influenced by the nitrogen fertilization, however it was altered by the growth cycles. The number of living leaves per tiller was superior on plants fertilized with highest N levels and at establishment growth, however an opposite effect was observed to the phylochron. The fertilization level 600 mg de N dm-3 of soil lead to an increase of 448% on herbage growth, and of 455% on herbage accumulation rates in relation to the 0 mg de N dm-3 of soil. The nitrogen fertilization provides positive responses to the biomass flow of Massai grass.

The objective of this study was to identify the pattern of deposition of feces by supplemented crossbred dairy cows after the lactation peak on cultivated areas under levels of intensification of the system and its effects on nitrogen cycling, with the aid of geostatistics, in the rainy period. Treatments were composed of two levels of nitrogen fertilization (equivalent to 400 and 800 kg N/ha/year) and two types of animals, according to the daily milk production. Geostatistical and descriptive analyses of the data were conducted. The data presented positive coefficients of skewness and platykurtic kurtosis. For the coefficient of variation, there was elevated alteration, with rest areas showing higher values and paddocks with a higher level of fertilization showing lower values.The climate factors radiation, temperature and relative humidity significantly influenced the dispersion and location of feces. As to the degree of spatial dependence, the classification varied from moderated to strong. The range was from 14.0 to 12.7 m for the rest areas and paddocks, respectively. Fertilization and concentrate supply affected the deposition and loss of nitrogen via feces, elevating its values as the nutritional uptake is elevated. Fecal deposition showed heterogeneity, with areas of greater concentration such as shades, entrance of the paddocks and threshing floor, showing deposition peaks that reach 1,051.2 kg N/ha/year.

This study evaluated the biomass flow of massai grass in regrowth subjected to different nitrogen levels (control - no fertilization; 400; 800; and 1200 N kg ha-1year-1) and under rotational stocking with sheep, in a completely randomized design with repeated measures over time. The leaf elongation rate increased with increasing nitrogen levels (N) and the fourth grazing cycle presented a lower value compared with the others. The stem elongation rate responded linearly with increasing levels of N, but it was not influenced by grazing cycles. The senescence rate of leaves remaining before grazing and after grazing were not influenced by the nitrogen fertilization or amended with successive grazing cycles. The phyllochron was influenced only by the nitrogen fertilization, with a decreasing linear response with nitrogen levels. Quadratic response was observed for the average length of leaves with increasing N levels and the grazing cycle 4 presented the lowest value for this variable. For each kilogram N ha-1 year-1, increases of 0.161 and 0.1604 kg ha-1 day-1 were verified in the herbage growth and accumulation rates, respectively. Nitrogen fertilization favors the biomass flow of massai grass, promoting an expressive increase in the production and accumulation of forage.

This study aimed to evaluate the growth index of massai grass during two regrowth cycles in a greenhouse under five levels of nitrogen (0, 150, 300, 450 and 600 mg N/dm³ of soil) and eight growth ages (5, 8, 11, 14, 17, 20, 23 and 26 days) in a split-plot design with five replications. The following variables were evaluated: net assimilation rate, herbage growth rate, relative growth rate, leaf area ratio, leaf weight ratio and specific leaf area. The effect of nitrogen was detected on the variables net assimilation rate (regrowths 1 and 2), leaf area ratio (regrowth 1), leaf weight ratio (regrowths 1 and 2), specific leaf area (regrowths 1 and 2) and herbage growth rate (regrowths 1 and 2). The growth ages influenced the relative growth rate (regrowth 2) and the net assimilation rate (regrowth 2). The net assimilation rate presented linear effect, estimated in 0.70 and 2.86 g/m² leaf.day-1 for the 0 and 600 mg N/dm³ soil, respectively (regrowth 1). For each milligram of N/dm³ added, the leaf area ratio was reduced in 0.0000258 m² leaf/g plant (regrowth 1). The herbage growth rate was estimated in 1.38 and 37.02 g/m².day-1 (regrowth 1), and 4.37 and 32.20 g/m².day-1 (regrowth 2) for the 0 and 600 mg N/dm³ soil, respectively. The massai grass' growth is favored by nitrogen fertilization, and little do the growth ages affect the growth index of the plants.

The objective of this study was to evaluate gas exchange in the massai grass during establishment and regrowth cycles in a greenhouse, using five nitrogen (N) fertilization levels. A completely randomized split-plot design of five nitrogen levels (0; 150; 300; 450 and 600 mg N•dm-3 of soil) was employed with the N levels as plots, and the cycles (establishment, regrowth 1 and 2) as subplots, evaluated with five replicates. We evaluated leaf transpiration (E), leaf temperature (TFOL), leaf photosynthesis rate (A), leaf carbon dioxide concentration (Ci), stomatal conductance (gs), photosynthesis/transpiration ratio (A/E), photosynthesis/conductance ratio (A/gs), chlorophyll relative index (CRI), and nitrogen sufficiency index (NSI). Growth cycles influenced all physiological characteristics, except for NSI. N fertilization levels affected TFOL, A, CRI and NSI variables, whereas for gs, E, Ci, A/E and A/gs it did not occur. A increased from 6.38 to 10.33 µmol•m-2.s-1, at levels 0 and 600 mg N•dm-3 of soil, respectively. Gas exchange in the massai grass was favored by nitrogen fertilization, since the cycles amended these characteristics of the grass.

To evaluate biomass components of Massai grass under five doses of N (0, 150, 300, 450 and 600 mg N/dm³ soil) during three cycles of growth (establishment, regrowth 1 and regrowth 2) this study was carried out. The experiment was carried out in a greenhouse, in a completely randomized design with measures repeted over time and five replications. In the three cycles, nitrogen doses had increasing linear effect on green herbage dry matter (GHDM), green leaf dry matter (GLDM), on the tiller population density (TPD) and on forage density. Canopy height and foliage height were the highest ones in establishment of regrowth 2, respectively, and they decreased at the highest doses of nitrogen. Irrigation depth was the greatest at the highest doses and in regrowth 1. Water use efficiency responded positively to the doses, being the regrowth 2 the highest values were obtained at the highest doses of nitrogen. Nitrogen use efficiency by Massai grass is influenced by fertilizantion as well as by the cycles. Nitrogen fertilization has positive effects on the components of Massai grass biomass.

Objetivou-se avaliar os componentes da biomassa do resíduo pós-corte em capim-massai submetido a cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg N dm-3 de solo) num delineamento inteiramente casualizado, com cinco repetições (vasos) em casa de vegetação. Avaliaram-se a altura residual, a densidade populacional de perfilhos (DPP), a massa seca de forragem total residual (MSFTr), de forragem verde residual (MSFVr), de forragem morta residual (MSFMr), de lâmina foliar verde residual (MSLVr), de colmo verde residual (MSCVr), relação lâmina foliar/haste (LF/C), a massa seca radicular (MS radicular) e a relação parte aérea/raiz. Observou-se efeito quadrático dos níveis de adubação nitrogenada sobre a altura residual. As variáveis MSFTr, MSFVr e MSCVr responderam positivamente, enquanto a MSLVr revelou comportamento quadrático com os níveis de N. Constatou-se valores estimados de 13,35 e 39,73 g MS/vaso para MSFTr, de 9,71 e 24,69 g MS/vaso para MSFVr e de 3,65 e 15,07 g MS/vaso para MSFMr nas doses de 0 a 600 mg N dm-3 de solo, respectivamente. A MS radicular respondeu positivamente às doses de N. A adubação nitrogenada proporciona resultados positivos sobre as características estruturais do resíduo pós-corte do capim-massai.

After cut residue of Massai grass under five nitrogen fertilized levels were evaluated. A completely randomized design with five nitrogen levels (0; 150; 300; 450 and 600 mg N dm-3 of soil) and five replicates (plots) in greenhouse was used. It was evaluated the residual canopy height (RCH), the tiller population density (TPD), the total residual forage dry mass (TFDM), the residual green forage dry mass (GFDM), the senescent forage dry mass (SFDM), the residual green leaf dry mass (GLDM), the residual green culm dry mass (GCDM), leaf/culm ratio (L/C), root dry mass (RDM) and above ground/root ratio (A/R). There was square effect of nitrogen fertilization on RCH. There were crescent and linear effect of nitrogen fertilization on TFDM, GFDM and GCDM. There was square effect of nitrogen fertilization on GLDM. The values were estimated in 13.35 and 39.73 g DM/plot to TFDM; 9.71 and 24.69 g DM/plot to GFDM and 3.65 and 15.07 g DM/plot to SFDM on 0 and 600 mg N dm-3 of soil, respectively. The RDM presented positively response to the N levels. It was concluded that the nitrogen fertilizing brought benefits for all structural characteristics after cut of Massai grass.

Avaliou-se a estrutura do dossel em pastagem de Panicum maximum Jacq. cv. Tanzânia sob lotação rotativa com três períodos de descanso (PD), definidos de acordo com o tempo para a expansão de 1,5; 2,5 e 3,5 novas folhas por perfilhos ao longo dos ciclos de pastejo. Estimaram-se as produções de massa seca de lâmina verde (MSLV), colmo verde (MSCV), de forragem morta (MSFM) e de altura; as relações folha-colmo (F/C), material vivo-morto (MV/MM), no pré e pós-pastejo; as taxas de crescimento da cultura (TCC) e acúmulo de forragem (TAC), a densidade populacional de perfilhos (DPP) no pré-pastejo e o índice de área foliar residual (IAFr). Com o avançar dos ciclos de pastejo, as diferenças entre os três períodos de descanso para as variáveis altura, produção de MSLV e MSCV foram acentuadas, especialmente no final do período experimental. A quantidade de MSFM se manteve semelhante dentro de cada período de descanso ao longo dos ciclos de pastejo, porém, na média dos ciclos de pastejo, o período de descanso para expansão de 3,5 folhas foi superior. As relações F/C e MV/MM foram maiores nos piquetes mantidos sob os períodos de descanso para expansão de 1,5 e 2,5 folhas em relação ao de 3,5 folhas. Os maiores valores para TCC e TAC foram obtidos nos piquetes mantidos sob períodos de descanso para expansão de 2,5 e 3,5 folhas. A densidade de perfilhos foi maior nos piquetes mantidos sob período de descanso para expansão de 2,5 folhas em relação ao de 3,5 folhas. O período de descanso para expansão de folhas é o mais indicado para o manejo de pastagens de Panicum maximum cv. Tanzânia com ovinos, pois permite a obtenção de boas produções de folhas em relação aos colmos sem comprometer a densidade populacional de perfilhos. Entretanto, com esse período de descanso, verifica-se aumento da altura pós-pastejo, a qual deve ser controlada por meio de roçada mecânica ou manual.

The canopy structural traits of tanzaniagrass (Panicum maximum Jacq. cv Tanzania) pastures under three resting periods (PDs), defined as the time to complete the expansion of 1.5, 2.5, and 3.5 new leaves per tiller, along several grazing cycles (CPs), were evaluated. The following response variables were evaluated: green leaf dry matter mass (MSLV), green stem dry matter mass (MSCV), dead forage dry mass (MSFM), canopy height, leaf/stem and live/dead material ratios at pre- and post- grazing, crop growth rate (TCC) and net accumulation rate (TAC), tiller populational density (DPP) before grazing, and the residual leaf area index (IAFr). Differences among the PDs were acentuated toward the end of the experimental period for the variables canopy height, MSLV, and MSCV. The MSFM was not modified during the CPs in each PDs, but, averaging all the cycles, the 3.5 leaves PD pastures showed higher MSFM than the others. The leaf/stem and the live/dead material ratios were higher at the 1.5 and 2.5 leaves PDs pastures, than at the 3.5 leaves PD pasture. The 2.5 and 3.5 leaves PD pastures showed the highest TCC and TAC values. The DPP was higher at the 2.5 leaves PD pastures, than at the 3.5 leaves PD pasture. The PD for the expansion of 2.5 leaves per tiller is the better indication to manage Panicum maximum cv. Tanzânia pastures with sheep, because it promotes higher proportion of leaves, without decreasing the tiller population density. However, this management decision leads to higher post-grazing stubble height, which may need to be controled by manual or mechanical mowing.

Avaliou-se o fluxo de biomassa em Panicum maximum cv. Tanzânia pastejado por ovinos com três períodos de descanso (PD), definidos pela expansão de 1,5; 2,5 e 3,5 novas folhas por perfilho, em um delineamento inteiramente casualizado, com duas repetições (piquetes). Estimaram-se as taxas de alongamento de lâmina foliar total (TAlF), de senescência de lâminas foliares remanescentes do pastejo anterior (TSFA), de senescência das novas folhas formadas no PD (TSFP) e de senescência total (TSFT=TSFA+TSFP), a taxa de alongamento das hastes (TAlH), a razão entre as TAlF das folhas 1 e 2 (razão TAlF1/TAlF2), a densidade populacional de perfilhos (DPP), o filocrono e as taxas de crescimento (TCC) e de acúmulo (TAC) da cultura. A razão TAlF1/2 não foi afetada pelos PD, mas reduziu ao longo dos ciclos na pastagem sob PD 3,5. A TAlF não foi afetada pelos PD. A TAlH, a TSFA e a TSFT na pastagem sob PD 1,5 foram menores que nas demais. Houve TSFP somente na pastagem sob PD 3,5. O filocrono da pastagem sob PD 1,5 foi superior ao observado nas demais. A densidade populacional de perfilhos (DPP) da pastagem sob o PD 2,5 foi similar à verificada na pastagem sob PD 1,5 e superior à verificada sob PD 3,5. Houve redução na DPP ao longo dos ciclos na pastagem sob PD 3,5. As taxas de crescimento (TCC) e de acúmulo (TAC) foram superiores na pastagem sob PD 2,5. O prolongamento do PD elevou as TAlH e TSFT e reduziu a DPP e a TAC. Portanto, o PD do capim-tanzânia pastejado por ovinos não deve exceder o tempo necessário à expansão de 2,5 novas folhas por perfilho.

The biomass flow in Panicum maximum cv. Tanzânia pasture grazed by sheep under three resting periods (PD), defined by the expansion of 1.5; 2.5 and 3.5 new leaves per tiller (1.5F; 2.5F and 3.5F, respectively) was evaluated in a randomized completely design with two replicates (paddocks). It was determined the leaf elongation rate (TAlF), the residual leaf senescence rate (TSFA), the post-grazing leaf senescence rate (TSFP) and the total leaf senescence rate (TSFT), the stem elongation rate (TAlH), the TAlF of leaves 1 and 2 ratio (TALF1/2), the tiller population density (DPP), the phylochron and the crop growth (TCC) and accumulation (TAC) rates. The TAlF1/2 ratio was not affected by the PD, however, it decreased over the cycles at the 3.5F PD pasture. The TAlF was not affected by the PD. The TAlH was inferior at the 1.5F PD pasture, as well as the TSFA and the TSFT. There was TSFP only at the 3.5F PD pasture. The phylochron of the 1.5F PD pasture was superior to the others. The DPP of the 2.5F PD pasture was similar to that of the 1.5F PD pasture, and it was superior to the 3.5F PD pasture. There was reduction of the DPP following the cycles at the 3.5F PD pasture. The TCC and the TAC of the 2.5F PD pasture were superior than the others. The extension of the PD raised the TAlH and the TSFT and reduced the DPP and the TAC. As a conclusion, the resting period should not exceed the time necessary to the expansion of 2.5 leaves on the tiller for tanzaniagrass pastures grazed by sheep.