Rodrigo Gregório da Silva

Fluxo de biomassa em capim-tanzânia pastejado por ovinos sob três períodos de descanso

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.

Características estruturais do dossel de pastagens de capim-tanzânia mantidas sob três períodos de descanso com ovinos

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.

Biomass flow in massai grass fertilized with nitrogen under intermittent stocking grazing with sheep

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 -1 year -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.

Componentes estruturais do resíduo pós-corte em capim-massai adubado com cinco doses de nitrogênio

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.

Análise econômica da produção de ovinos em lotação rotativa em pastagem de capim tanzânia (Panicum maximum (Jacq))

The breeding of ovine and caprine possess high partner-econo-mic importance in the Northeast, however, the low genetic potential of the herds, as well as the scarcity of pastures during the dry season, limits the productivity and lucrativeness indices to a low level. The use of cultivated pastures is a way to maintain in high level the carrying capacity of the pasture over the year. This work was conducted with the aim of increase the productivity, expand the income and stimulate the producer to invest in new productive techniques. 100 Sem RaA§a Definida sheep and three periods were used. The rest period consisted of: treatment 1 - time for expansion of 1.5 new leaves per tiller; treatment 2 - time for expansion of 2.5 new leaves per tiller and treatment 3 - time for expansion of 3.5 new leaves per tiller. The analysis considered the use of 1, 3 or 5 hectares of pasture, fenced by campestre screen or electric fence. The efficiency indices adopted were: benefit cost relation, liquid present value, return internal tax, and sensitivity analysis. The 2.5 leaves rest period exploring at least 5.0 hectares presented best performance, in terms economics, biological and environmental. So, to promote economic return, it is necessary to use sheep of higher genetic potential and pastures areas above 5.0 hectares.

Fluxo de biomassa em capim-massai durante o estabelecimento e rebrotação com e sem adubação nitrogenada

A producao 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 rebrotacao, em casa de vegetacao, sob cinco doses de nitrogenio (0; 150; 300; 450 e 600 mg de N dm-3 de solo), em delineamento inteiramente casualizado, com medidas repetidas no tempo, e cinco repeticoes. A taxa de alongamento foliar foi incrementada pelas doses de nitrogenio (N) e o crescimento de estabelecimento apresentou maior valor, em relacao ao das rebrotacoes. A taxa de alongamento das hastes nao foi influenciada pelas doses de N. O crescimento de estabelecimento apresentou maior valor para esta variavel, em relacao ao das rebrotacoes. A taxa de senescencia foliar anterior nao sofreu influencia das doses de N, porem, foi alterada entre os ciclos de crescimento. O numero 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 producao de forragem, e de 455%, na taxa de acumulo de forragem, em relacao aquelas do manejo sem N. A adubacao nitrogenada proporciona respostas positivas nas variaveis do fluxo de biomassa do capim-massai.

Trocas gasosas e índices de crescimento em capim-braquiária manejado sob lâminas de irrigação e idades de crescimento.

This research aimed to evaluate the gas exchange and growth index of Brachiaria decumbens under five water supply (3.84, 4.39, 6.19, 8.62 and 10.46 mm day-1). A completely randomized with split-plot design with five irrigation depth being the parcels and ages (10, 17, 24 and 31 days), the subparcels, with four replicates. It was observed interaction between irrigation depth and ages for leaf transpiration, leaf temperature, rate of photosynthesis and leaf weight ratio. Quadratic responses with minimum values were observed to the internal CO2 concentration and specific leaf area (0.0055 m2 leaf g -1 leaf) with advance in ages. The internal concentration of CO2 revealed values of 220.09 and 176.20 ppm to 10 and 31 days, respectively, with minimum (173.68 ppm) to 27 days. It was observed quadratic response with maximum value (25.04 g m-2 leaf day-1) to the net assimilation rate with increasing ages. Decreasing linear responses were observed to the relative growth rate and leaf area ratio with increasing ages. The relative growth rate presented values of 0.097 and 0.048 g g-1 day-1, with 10 and 31 days, respectively. The growth ages provided changes on gas exchange and growth index of Brachiaria grass, however, these characteristics are little influenced by irrigation depth under the conditions of this study.

Biomass components in Massai grass during establishment and regrowth under five nitrogen fertilization levels

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.

Gas exchange in massai grass under five nitrogen fertilization levels during establishment and regrowth

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.

Biomass flow and water efficiency of cactus pear under different managements in the Brazilian Semiarid

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 Quixada and Tejucuoca, in Ceara. This was a split-plot randomized block design, with four replicates. In Quixada and Tejucuoca, the N and P combinations and harvest frequencies influenced the productions rates of different cladode orders and rain use efficiency in cactus pear. In Quixada, 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 Tejucuoca, 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. [Fluxo de biomassa e eficiencia hidrica da palma forrageira sob diferentes manejos no Semiarido Brasileiro]. Resumo: A adubacao balanceada e fator de importância comprovada na otimizacao do crescimento e produtividade das culturas. Objetivou-se avaliar o fluxo de biomassa e a eficiencia de uso da chuva na palma forrageira cv. Gigante, adubada com combinacoes de doses de nitrogenio (10; 70; 100; 130 e 190 kg ha-1 ano-1 de N) e fosforo (10; 70; 100; 130 e 190 kg ha-1 ano-1 de P2O5), nas frequencias de colheita anual e bianual, nas regioes de Quixada e Tejucuoca, no Ceara. Utilizou-se delineamento em blocos casualizados, em arranjo de parcelas subdivididas, com quatro repeticoes. Em Quixada e Tejucuoca, as combinacoes de N e P e frequencias de colheita influenciaram as taxas de producoes de diferentes ordens de cladodios e a eficiencia de uso da chuva na palma forrageira. Em Quixada, na colheita anual, verificou-se taxa de producao de forragem (TPF) de 10,3 kg ha-1 dia-1 na combinacao N/P2O5 de 190,0/190,0 kg ha-1 ano-1 e na colheita bianual, observou-se maxima TPF de 4,6 kg ha-1 dia-1 na combinacao N/P2O5 de 114,6/136,8 kg ha-1 ano-1. Em Tejucuoca, na colheita anual, constatou-se maxima TPF de 30,0 kg ha-1 dia-1 na combinacao 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 combinacao N/P2O5 de 190,0/33,4 kg ha-1 ano-1. As taxas de producoes de biomassa e eficiencia de uso da chuva sao otimizadas com o balanco de doses combinadas de nitrogenio e fosforo