AM fungi mediated bioaccumulation of hexavalent chromium in Brachiaria mutica-a mycorrhizal phytoremediation approach.

The experiment was designed to evaluate the roles of Rhizophagus irregularis on chlorophyll fluorescence and chromium bioaccumulation in a grass species (Brachiaria mutica) by supplementing Cr+6 at different concentrations. Arbuscular Mycorrhizal Fungi (AMF) association facilitated lessening of chromium level in contaminated soil and enhanced chromium bioavailability in Brachiaria mutica. The mycorrhizal inoculated increased the chlorophyll (0.925 mg/g), carotenoid (0.127 mg/g), protein (2.883 mg/g), proline (0.889 mg/g) contents and activities of antioxidant enzymes like catalase, ascorbate peroxidase and glutathione peroxidase. The mycorrhizal inoculated plants also showed enhanced overall photosynthetic performance (PIϕ = 2.473) and enhanced PS-II to PS-I electron transport as evident from yield parameter (0.712) and TR0/RC (2.419) for 60 mg/kg Cr+6 treatment. The observations suggest that AMF association could defend the plants from chromium stress by elevating the number of antioxidants in plants. Rhizophagus irregularis was found to maintain a successful symbiotic relationship with Brachiaria mutica in chromium contaminated soil. The observations recommended that Rhizophagus irregularis in association with Brachiaria mutica would be an innovative approach for decontamination of Cr+6.

Removal of phosphorous and nitrogen from wastewater in Brachiaria-based constructed wetland.

Considering the prevalence of eutrophication of water bodies, sustainable treatment technologies like constructed wetlands (CWs) have come up as a promising alternate for nutrient removal and wastewater treatment. The present study was undertaken to investigate the potential of Brachiaria-based constructed wetland for removal of phosphorus and nitrogen in different seasons of a sub-tropical region. The CW cell could efficiently remove phosphate and nitrogen under varying influent concentrations across different seasons. Average removal of total phosphate increased from 55.2% (winter) to 78.5% (spring), 80.7% (autumn), and 85.6% (summer), and maximum removal rate was 384.4 mg/m2-day during the summer season. The soluble/available phosphate was removed on priority owing to its easy bio-availability. The removal efficiency of Brachiaria increased with increasing influent phosphate concentration (5-20 mg/l), if supplemented with nitrogen maintaining the N:P ratio of 5:1. This highlighted the characteristic of Brachiaria to absorb chemical shocks w.r.t. phosphate. The neutral pH (6.2-8.3) and oxidising conditions in rhizosphere ruled out possibility of binding of phosphate with cations (Ca, Fe, and Al) in sediments. Ambient temperature and sunshine hours regulated evapotranspiration and hence nutrient removal. Simultaneous removal of nitrogen (75.6-84.6%) by Brachiaria indicated that it can serve dual purpose of nutrient removal and fodder-production for livestock, thus serving as a sustainable prototype for rural communities in sub-tropical regions.

Nutritional quality and organic matter degradability of Brachiaria spp. agronomically biofortified with selenium.

Selenium (Se) fertilisation in grazing systems can improve the quality of animal forage, but there are few studies addressing the influence of Se fertilisation on the chemical composition and ruminal degradability of forage fertilised with Se. The aim of this study was to evaluate the chemical composition and in vitro assays of truly degraded organic matter (TDOM), short-chain fatty acids (SCFA) total gas (GP) and methane (CH4 ) production of two harvests of Brachiaria brizantha cv. Marandu fertilised with urea coated with B, Cu and sodium selenate for 0, 10, 20, 40, 80 and 160 g/ha of Se. Selenium content in forage increased linearly with the different doses at 30 and 60 days after fertilisation. However, doses of 20 and 80 g/ha Se fertilisation yielded positive effects increasing Se content and truly degraded organic matter in vitro of Brachiaria brizantha cv. Marandu.

Pleurotus spp. cultivation on Brachiaria sp. straw treatment with alkaline water: Oyster mushroom and substrate treatment.

The aim of this research was to evaluate the efficiency of aqueous alkali-treated Brachiaria straw for the cultivation of appropriate species of oyster mushroom. The substrate used in the cultivation of various Pleurotus spp. was soaked for 20min by using two different procedures: (i) 0.5-2.0% Ca(OH)2 in 100L water, and (ii) 50-250L water. As a result, 1% Ca(OH)2 dissolved in 100L water and 3.5kg of Brachiaria straw presented the best production. The most suitable species for the application of the present method were P. pulmonarius and P. sapidus. The success of this technique is directly related to the concentration of Ca(OH)2 and water, the species, and the origin and quality of raw material used as the substrate in the production of oyster mushroom.

GID1 expression is associated with ovule development of sexual and apomictic plants.

KEY MESSAGE: BbrizGID1 is expressed in the nucellus of apomictic Brachiaria brizantha, previous to aposporous initial differentiation. AtGID1a overexpression triggers differentiation of Arabidopsis thaliana MMC-like cells, suggesting its involvement in ovule development. GIBBERELLIN-INSENSITIVE DWARF1 (GID1) is a gibberellin receptor previously identified in plants and associated with reproductive development, including ovule formation. In this work, we characterized the Brachiaria brizantha GID1 gene (BbrizGID1). BbrizGID1 showed up to 92% similarity to GID1-like gibberellin receptors of other plants of the Poaceae family and around 58% to GID1-like gibberellin receptors of Arabidopsis thaliana. BbrizGID1 was more expressed in ovaries at megasporogenesis than in ovaries at megagametogenesis of both sexual and apomictic plants. In ovules, BbrizGID1 transcripts were detected in the megaspore mother cell (MMC) of sexual and apomictic B. brizantha. Only in the apomictic plants, expression was also observed in the surrounding nucellar cells, a region in which aposporous initial cells differentiate to form the aposporic embryo sac. AtGID1a ectopic expression in Arabidopsis determines the formation of MMC-like cells in the nucellus, close to the MMC, that did not own MMC identity. Our results suggest that GID1 might be involved in the proper differentiation of a single MMC during ovule development and provide valuable information on the role of GID1 in sexual and apomictic reproduction.

Pleurotus spp. cultivation on Brachiaria sp. straw treatment with alkaline water

Abstract The aim of this research was to evaluate the efficiency of aqueous alkali-treated Brachiaria straw for the cultivation of appropriate species of oyster mushroom. The substrate used in the cultivation of various Pleurotus spp. was soaked for 20 min by using two different procedures: (i) 0.5-2.0% Ca(OH)2 in 100 L water, and (ii) 50-250 L water. As a result, 1% Ca(OH)2 dissolved in 100 L water and 3.5 kg of Brachiaria straw presented the best production. The most suitable species for the application of the present method were P. pulmonarius and P. sapidus. The success of this technique is directly related to the concentration of Ca(OH)2 and water, the species, and the origin and quality of raw material used as the substrate in the production of oyster mushroom.

Ethological activities, ruminal parameters and weight gain of calves supplemented with different amounts of sodium chloride / Atividades etológicas, variáveis ruminais e ganho de peso de bezerras suplementadas com quantidades crescentes de cloreto de sódio

The daily weight gain, behavioral activities (grazing, ruminating and water consumption) and the number of rumen protozoa, pH, NH3, and the osmolarity of rumen fluid was evaluated for four groups of six calves HPB/Zebu submitted to daily intake of 15, 30, 60 and 90g of NaCl during 135 days (9th Jan. to 24th May 2008).Throughout the experimental period the calves were in perfect health condition and did not show any signs suggestive of chronic sodium poisoning. There was no significant difference in average daily gain of the calves as the intake of NaCl increased. No significant behavioral changes were observed in the activities of grazing and rumination. However, there was a noticeable change in the frequency of water consumption in the calves that ingested 90g/d of NaCl; they went more often to the trough and drank more water than the group that ingested only 15g sodium chloride/d. The osmolarity of ruminal liquid was higher in the group of calves fed 90g of NaCl/d. The pH, NH3 concentration and number of rumen protozoa was within the normal range.

O desempenho ponderal, as atividades comportamentais (pastar, ruminar e beber água) e a estimativa do número de protozoários, pH, NH3 e da osmolaridade do líquido ruminal foram avaliados em quatro grupos de 6 bezerras HPB/Zebú submetidas a ingestão diária de 15, 30, 60 e 90 gramas de NaCl por 135 dias (9 jan. a 24 mai. 2008). Por todo o período experimental, os animais estiveram em perfeita condição de saúde e não exibiram quaisquer sinais sugestivos da intoxicação crônica por sódio. Não houve diferença significativa no ganho médio diário dos animais à medida que a ingestão de NaCl aumentou. Não foram detectadas alterações comportamentais significativas nas atividades de pastejo e ruminação. Entretanto, houve perceptível alteração na atividade de beber água e os animais que ingeriram 90g/d de NaCl aumentaram suas frequências de ida ao bebedouro e beberam mais água em relação ao grupo que ingeriu 15g/d. A osmolaridade do líquido ruminal foi sempre maior no grupo de animais que consumiram 90g/d de NaCl e o pH, a concentração de NH3 e número de protozoários também se situaram na faixa considerada normal.

A differential phenotypic expression of a divergent spindle mutation in interspecific Brachiaria hybrids.

Several mutations are known to alter the normal progression of meiosis and can be correlated with defects in microtubule distribution. The dv mutation affects the spindle organization and chromosomes do not converge into focused poles. Two Brachiaria hybrids presented the phenotypic expressions of dv mutation but exhibited many more details in the second division. Bivalents were distantly positioned and spread over a large metaphase plate and failed to converge into focused poles. Depending on the distance of chromosomes at the poles, telophase I nuclei were elongated or the chromosomes were grouped into various micronuclei of different sizes in each cell. The first cytokinesis occurred. However, when there were micronuclei, a second cytokinesis immediately took place dividing the prophase II meiocytes into three or four cells. In each meiocyte, meiosis progressed to the second division. Slightly elongated nuclei or micronuclei were recorded in telophase II. After a third cytokinesis, hexads or octads were formed. Pollen grains of different sizes were generated. One of these hybrids presented a higher frequency of abnormal cells than when previously analyzed. The fate of these hybrids as genitors or as candidates for cultivars in the Brachiaria breeding program is discussed.

Desempenho e consumo de matéria seca de bovinos sob suplementação protéico-energética, durante a época de transição água-seca / Protein and energy supplementation of steers during the transition of the wet to the dry season

Avaliou-se o efeito da suplementação protéico-energética em dois níveis de ingestão diária, 0,17 e 0,37 por cento do peso vivo médio, sobre o no desempenho e consumo de matéria seca por bovinos, em pastagens de Brachiaria brizantha cv. Marandu. Para avaliação do desempenho foram utilizados 42 novilhos (Holandês x Gir - HG), com média de 211kg de peso vivo inicial (PVI) e para a avaliação do consumo de matéria seca total (CMST) e de forragem (CMSF) foram usados 15 novilhos inteiros HG, com 239kg de PVI. Os tratamentos foram: SM - controle; SUP1 - suplementação protéico-energética com ingestão média diária de 0,17 por cento do peso vivo e SUP2 - suplementação protéico-energética com ingestão média diária de 0,37 por cento do peso vivo (PV). Os valores do CMSF foram de 2,6, 2,4 e 2,3 por cento PV, e os de CMST 2,6, 2,6 e 2,6 por cento PV, para SM, SUP1 e SUP2, respectivamente. Esses valores não diferiram entre si (P>0,05). A suplementação protéico-energética proporcionou maior ganho de peso, 0,54, 0,66 e 0,75kg/cabeça/dia para SM, SUP1 e SUP2, respectivamente.

The effect of two levels of daily intake (0.17 percent and 0.37 percent of live weight) of protein and energy supplementation on weight gain and on dry matter intake of bulls grazing Brachiaria Brizantha cv. Marandu grass was evaluated. Forty two bulls (Holstein x Gir - HG), averaging 211kg initial LW, were used in the performance trial, and 15 HG steers, averaging 239kg initial LW, for evaluation of total dry matter intake (TDMI) and forage dry matter intake (FDMI). The treatments were: MS - mineral supplementation, SUP1 - protein and energy supplementation with an average daily intake of 0.17 percent of the live body weight, and SUP2 - protein and energy supplementation with an average daily intake of 0.37 percent of the live body weight. The average FDMI intakes were 2.6, 2.4, and 2.3 percent of the LW, for MS, SUP1 and SUP2, respectively. The average TDMI intakes were 2.6, 2.6, and 2.6 percent for MS, SUP1, and SUP2, respectively. Protein and energy supplementation increased weight gain from 0.54kg/day in the MS treatment to 0.66 and 0.75kg/day for SUP1 and SUP2, respectively.

Influence of fertilizer levels on phytoremediation of crude oil-contaminated soils with the tropical pasture grass Brachiaria brizantha (hochst. ex a. rich.) stapf.

Determination of fertilizer levels in phytoremediation of petroleum hydrocarbons is a complex issue, since nutrient demands of the plant and of degrading microorganisms in the rhizosphere have to be considered In the present work, three fertilizer levels were tested in a greenhouse experiment with the aim of optimizing growth of the tropical pasture grass Brachiaria brizantha and enhance microbial degradation of heavy crude oil in soil Fertilizer was applied twice in a concentration of 200, 300, and 400 mg each of N, P, and K per kg soil before and after the first sampling (14 wk). The medium fertilizer concentration resulted in best root growth and highest absolute oil dissipation (18.4%) after 22 wk The highest concentration produced best shoot growth and highest relative oil dissipation after 14 wk (10.5% less than unplanted control). In general, degradation of total oil and grease was higher in planted than in unplanted soil, but differences diminished toward the end of the experiment. Next to fertiizer quantity, its composition is an important factor to be further studied, including the form of available nitrogen (N-NO3- vs. N-NH4+). Field trials are considered indispensable for further phytoremediation studies, since greenhouse experiments produce particular water and nutrient conditions.

Low phosphorus tolerance mechanisms: phosphorus recycling and photosynthate partitioning in the tropical forage grass, Brachiaria hybrid cultivar Mulato compared with rice.

The Brachiaria hybrid cv. Mulato is well adapted to low-fertility acid soils deficient in phosphorus (P). To study the grassy forage's mechanisms for tolerating low P supply, we compared it with rice (Oryza sativa L. cv. Kitaake). We tested by using nutrient solution cultures, and quantified the effects of P deficiency on the enzymatic activities of phosphohydrolases and on carbon metabolism in P-deficient leaves. While P deficiency markedly induced activity of phosphohydrolases in both crops, the ratio of inorganic phosphorus to total P in leaves was greater in Brachiaria hybrid. Phosphorus deficiency in leaves also markedly influenced the partitioning of carbon in both crops. In the Brachiaria hybrid, compared with rice, the smaller proportion of (14)C partitioned into sugars and the larger proportion into amino acids and organic acids in leaves coincided with decreased levels of sucrose and starch. Hence, in P-deficient leaves of the Brachiaria hybrid, triose-P was metabolized into amino acids or organic acids. Results thus indicate that the Brachiaria hybrid, compared with rice, tolerates low P supply to leaves by enhancing sugar catabolism and by inducing the activity of several phosphohydrolases. This apparently causes rapid P turnover and enables the Brachiaria hybrid to use P more efficiently.