Echinochloa Polystachya Research Articles

Biochemical responses of Echinochloa polystachya inoculated with a Trichoderma consortium during the removal of a pyrethroid-based pesticide

The biochemical response of plants exposed to pesticides and inoculated with microorganisms is of great importance to explore cleaning up strategies for contaminated sites with pyrethroid-based pesticides. We evaluated the effects of a Trichoderma consortium on the biochemical responses of Echinochloa polystachya plants during the removal of a pyrethroid-based pesticide. Plants were inoculated or not with the Trichoderma consortium and exposed to commercial pesticide H24®, based on pyrethroids. Pesticide application resulted in significant reduction in root protein content (58%), but enhanced content of malondialdehyde (MDA) in shoots, superoxide dismutase (SOD) activity in shoots and roots, and catalase (CAT) activity in roots. Inoculation of Trichoderma consortium in E. polystachya exposed to the pesticide resulted in increased protein content in roots and MDA content in shoots (2-fold). Trichoderma consortium improved protein content and SOD activity (140-fold) in plants. Fungal inoculation increased the removal (97.9%) of the pesticide in comparison to the sole effect of plants (33.9%). Results allow further understanding about the responses of the interaction between plants and root-associated fungi to improving the assisted-phytoremediation of solid matrices contaminated with organic pesticides.

Determination of optimal areas for the establishment of buffalo herds and German grass in Tabasco, Mexico

Objective: To determine optimal (suitable) areas for the establishment of buffalo (Bubalus bubalis) herds fattened with German grass (Echinochloa polystachya Kunth Hitchc), based on the biophysical environmental conditions that favor the comfort of the animal species and the best development of the plant species.Design/Methodology/Approach: An analysis of the bioclimatic parameters for water buffalo and the agroclimatic parameters for German grass was carried out in the state of Tabasco, Mexico. A comparative table of the optimal biophysical variables of water buffalo and German grass was developed from the digital soil geographic databases and the climatological normals recorded in the state of Tabasco. Edaphoclimatic maps were developed to establish buffalo herds associated with German grass, based on a cartographic cross-checking.Results: The soil-climatic aptitude map of both species was developed at a scale of 1:135,000.Study Limitations/Implications: Given its recent introduction, there is a lack of basic information on the edaphoclimatic conditions suitable for water buffalo in the state of Tabasco.Findings/Conclusions: The areas for the establishment of buffalo herds and German grass were identified. Regarding their potentiality, 4.29% of the state of Tabasco is suitable, 56.67% was classified as moderately suitable, and 38.48% is not suitable.

Will climate change favor exotic grasses over native ecosystem engineer species in the Amazon Basin?

Several anthropic disturbances, including deforestation, fires, the building of roads and dams, have intensified in Amazon in last decades. These disturbances contribute to an increase in the occurrence and intensity of extreme events, such as more frequent floods and more severe droughts, due to climate change. Along the Amazonian rivers, aquatic herbaceous plants, mainly of the Poaceae family, are very abundant and produce up to three times more biomass than the adjacent flooded forests, and some are considered ecosystem engineers given their structuring role in these environments. Invasive grasses have spread through the Neotropics and are gradually entering the Amazon via the Arc of Deforestation. These invasive species often attain high coverage, suppress other species, and become dominant in both disturbed and pristine habitats. The aim of this study was to establish the current and future distribution patterns of two native ecosystem engineer species (Echinochloa polystachya and Paspalum fasciculatum) and two invasive species (Urochloa brizantha and Urochloa decumbens) in the Amazon Basin. To predict the future climate, we used three scenarios, namely SSP1–2.6, SSP3–7.0 and SSP5–8.5 for the years 2040, 2080 and 2100, to project climatically suitable areas. The current climatically suitable range for the native ecosystem engineer species was estimated at 33–35% of the Amazon Basin, while the invasive ones have a range of 53–84% in potential climatically suitable areas. A decrease in the areas of suitability of the two ecosystem engineer species, E. polystachya and P. fasciculatum, was observed in all scenarios and years, while only the invasive U. brizantha showed an increase in suitable areas in all years. These results raise concerns about the invasion of grasses with high aggressive potential that could result in the exclusion of native ecosystem engineer species and their ecological roles.

Description of Four Dual-Purpose River Buffalo (Bubalus bubalis) Farms in Tropical Wetlands in Mexico. Part 1: Social Aspects, Herd Distribution, Feeding, Reproductive, and Genetic Management

This article characterizes four dual-purpose river buffalo farms (DPBPS) in south-southeastern Mexico. The objectives were to obtain a broader profile of this system and capture values related to buffalo breeding in that area. The study identified a group of producers with high levels of education (17 ± 1.15 years) and years of experience in agricultural systems (28.75 ± 10.81), especially with buffaloes (9 ± 1.83 years). Land tenure is private, and the average surface area of ranches is 428.75 ± 245.57 hectares, located mainly (92%) in flatlands and floodplains with an average number of animals per hectare 2.03 ± 0.69 AU/h. The area has various vegetable strata (grasses, bushes, trees). Feeding is based on the consumption of vegetable species like Camalote grass (Paspalum fasciculatum), West Indian Azuche grass (Hymenachne amplexicaulis), and Aleman grass (Echinochloa polystachya), complemented with minerals. Production units (PU) 2 and 3 add a low proportion of balanced feed. The average number of animals per PU is 611 ± 50. Dams and calves represent the largest proportions in the herds. The main breed raised in these buffalo production systems is Buffalypso (58% ± 21%), followed by Italian Mediterranean (24% ± 5%) and Murrah (10% ± 14%). The data collected show that the reproduction methods most often utilized, in order of frequency, are fixed-time artificial insemination (FTAI), direct mounting (DM), and estrus-detected artificial insemination (EDAI). Proportions are 61% ± 18%, 24% ± 25% and 14% ± 17%, respectively. The DPBPS studied are distinguished by the presence of owners and managers with high levels of education, extensive experience in agricultural systems, and the capacity and willingness to implement new technologies that permit continuous improvement. However, their experience in buffalo production is still limited, so there is ample room for improvement.

REMEDIATION OF NUTRIENTS FROM MUNICIPAL WASTEWATER USING GERMAN GRASS-AIDED FLOATING TREATMENT WETLAND

The potential of using German grass (Echinochloa polystachya) in FTWs (Floating Treatment Wetlands) to treat municipal wastewater was investigated in this study. This mesocosm-based study was conducted over a 7-day Hydraulic Retention Period (HRT) with a total of 28 experimental days following a Randomized Complete Block Design (RCBD) with four treatments and three replicates. To evaluate system efficiency, mean temperature, PH, total dissolved solids (TDS), and electrical conductivity (EC) were also measured along with nitrate and phosphate concentrations. On day 28, the nitrate removal rate obtained with Pickerel weed was 88.65 % while German grass showed 86.56 % of remediation. On the other hand, while Pickerelweed removed 9.5 % of phosphate, German grass removed 7.47 %. The study demonstrated that the use of German grass in FTWs can be highly effective in the removal of nitrate ions from wastewater, while the removal of phosphate ions was minimal.

Reuse of Treated Domestic Wastewater by Employing Artificial Wetlands in Panama

Reuse of treated wastewater in irrigation is an alternative to achieve greater water availability and benefits to the soil due to its nutrient content. It represents a solution to challenges in water management, climate change and water scarcity in dry seasons. In Panama’s Dry Arch, the lack of water is critical during dry season months, which makes it essential to look for sustainable alternatives as water source. This paper describes the use of artificial wetlands with horizontal subsurface flow, and we are going to use partially treated domestic wastewater. The aquatic plant types employed were Echinochloa polystachya (German grass) and Brachiaria arrecta (Tanner grass) with the objective of improve the quality of the effluent from the Wastewater Treatment Plant (WWTP) in Chitre for the irrigation of forages. This study was carried out from August to December 2019. Fine Gravel was used in this study as a substrate. The parameters analyzed were pH, Total dissolved solids, Electrical Conductivity, Chemical Oxygen Demand, Turbidity, Chlorides, Sulfates, Iron, Chromium+6, Copper; nutrients such as Total nitrogen and Total phosphorus. Fecal coliforms were also analyzed. Results showed that treated wastewater is a viable alternative for irrigation due to its high nutrient content, but it must be managed safely so as not to generate risks to public health.

Enteric methane emissions by young Brahman bulls grazing tropical pastures at different rainfall seasons in the Peruvian jungle.

The aim of this research was to measure enteric methane (CH4) emissions by young Brahman bulls grazing tropical pastures at different rainfall seasons in the Peruvian jungle. Fourteen 1.5-year-old, young bulls (280kg ± 18kg BW) were grazed on tropical grasses and legumes dominated by German grass [Echinochloa polystachya (Kunth) Hitch.] and minor proportion of Torourco grass [Paspalum conjugatum (P.J. Bergius) Roxb] and Leguminous Calopo (Calopogonium mucunoides Desv.) and Kudzú [Pueraria phaseoloides (Roxb.) Benth]. Enteric CH4 emission was measured by the sulfur hexafluoride (SF6) tracer-gas technique. Organic matter intake (OMI) was determined from organic matter digestibility (OMD) using a fecal protein crude index and fecal output estimated by the dosage of external markers. There was a difference in OMD between seasons (68 and 66% for the dry and rainy seasons, respectively; P < 0.0001). The OMI (6.7 and 7.4kg/day) and CH4 (178.7 and 298g/day) were higher (P < 0.05) in the dry season than in the rainy season, respectively. The yield of CH4 was lower (P < 0.0001) during rainy season (7.1%) than at the dry season (10.6%). The CH4 emission (g/day) was correlated with OMD (%) (r = 0.74, P < 0.0001). Enteric CH4 emissions of young bulls grazing mixtures of tropical pastures were significantly lower in animals grazing on the rainy-season, expressed either through unit of absolute emission, intake or as percentage of the GEI. Likewise, OMD of consumed pasture was the most important factor determining CH4 emission.

The potential association of Echinochloa polystachya (Kunth) Hitchc. with bacterial consortium for petroleum degradation in contaminated soil

In recent years, environmental impacts related to the contamination of ecosystems by petroleum have become frequent. In contact with the environment, petroleum can cause toxic effects in the biodiversity and on human health and compromise both water and land resources. Among the strategies to overcome this issue, bioremediation stands out as viable and promising alternative for environmental decontamination. To bioremediate petroleum-contaminated sites, phytoremediation and bioaugmentation techniques can be used. Thus, this research aimed to evaluate through a pot experiment four bioremediation strategies: (1) natural attenuation, (2) phytoremediation with Echinochloa polystachya, (3) bioaugmentation with bacterial consortium and (4) bioaugmentation-assisted phytoremediation, for the treatment of a co-contaminated soil presenting 100 g kg−1 of petroleum. In addition, two control treatments were carried out with substrates not contaminated with petroleum: (5) control with E. polystachya and (6) control treatment with bacterial consortium and E. polystachya. The experiment lasted 60 days in a greenhouse. The survival rate of E. polystachya was 100% in the contaminant tolerance aspect, resulting in increased stomatal density and aerenchyma, affecting few parameters of the plant, which demonstrate its phytoremediation capacity. In all treatments, petroleum degradation occurred. The highest degree of total petroleum hydrocarbon removal was obtained for contaminated soil cultivated with E. polystachya (phytoremediation), followed by contaminated soil cultivated with E. polystachya and bacterial (bioaugmentation-assisted phytoremediation treatment) and contaminated soil treated with bacterial consortium (bioaugmentation). Natural attenuation was less effective, proving the efficiency of the phytoremediation by E. polystachya and bacterial consortium, that responded positively to the stresses generated by contamination. However, further studies should direct to aim understanding the metabolic processes involved in the degradation and that these approaches to assist in environmental decontamination.

Impacto del régimen pluvial en la composición química, digestibilidad y producción de metano de Echinochloa polystachya (Kunth) Hitch

Impacto del régimen pluvial en la composición química, digestibilidad y producción de metano de Echinochloa polystachya (Kunth) Hitch

Effect of different sources of water on water quality and growth performance of growing bull

The experiment was conducted to investigate the effect of different sources of water on feed intake and growth performance of growing bull. For this study, sixteen indigenous bulls (Bos indicus), around two years age (132.5±20.5 kg of LW), were divided into four groups having four animals in each treatment group. The animals were supplied with four different sources of water viz. Deep Tube Well Water (DTW =T1), Supply Water from reserve tank (SW = T2), Pond water (PW = T3) and River water (RW = T4). All the animals were fed German Grass (Echinochloa polystachya L.) and concentrate mixture. All the animals were free access to water. Live weight was recorded initially and week interval till end of the feeding trial (12 weeks). The results revealed that animal belonging T1 treatment group showed best growth performance was better in comparison to other treatment groups. Dry matter intake (DMI) was highest for T1 group (3.08 ± 0.08 kg/d) and lowest for T4 group (2.81 ± 0.18 kg/d). The digestible nitrogen free extract (DNFE) and total digestible nutrient (TDN) were higher (P&lt;0.05)in T1 group compared to other groups. The highest daily body weight gain (336.49±59.40 g/d) was observed in T1 group. Based on the results, it is concluded that deep tube well water (T1) is suitable for cattle for its quality which showed positive impact on intake and growth of animals. Further study might be needed to compare the cost involvement for different sources of water and economy of growth of animals.&#x0D; Bang. J. Anim. Sci. 2019. 48 (1): 9-16

Biomass and nutritional evaluation of German grass (Echinochloa polystachya) cultivated on floating bed

German and Napier grasses were cultivated on floating agricultural bed at the valley of Sylhet Agricultural University (SAU) to find out a suitable fodder for floating bed fodder cultivation. Later, German grass was cultivated on five floating beds at Hemupara of Jaintapur, Sylhet and also produced at land of SAU campus. German grass samples from both floating beds and land, as well as local Bermuda grass from Hemupara were evaluated for assessment of biomass production, proximate and fiber composition. There was no significant difference in length and production of German grass cultivated on floating bed and land cultivation. German grass production cost on floating bed was 2.3 Tk/kg. German grass from floating bed contained more ether extract, Ash, Neutral detergent fiber and cellulose than that from land cultivation. DM, Ash, CP, EE, CF and NFE of German grass on floating beds at Hemupara were 199.7g/kg, 20.1g/kg, 57.2g/kg, 37.2g/kg, 411.8gm/kg and 273.9g/kg respectively. The fiber components of German grass on floating beds were NDF (696.4g/kg), ADF (452.2g/kg), ADL (100.1g/kg), cellulose (244.1g/kg) and hemicellulose (352.1g/kg). German grass can be considered as a suitable fodder for floating bed fodder cultivation when there is long term water logging as an alternative fodder production practice in Bangladesh.Bang. J. Anim. Sci. 2017. 46 (4): 249-257

Feeding of processed vegetable wastes to bulls and its potential environmental benefit.

The study was conducted with the objectives to quantify year round availability of different vegetables waste (VW) in a wholesale market and to determine the inclusion level of a processed VW (VWP) in the diets of bulls. The daily VW biomass availability at Kawran bazaar, Dhaka, Bangladesh was quantified by weighing the vegetable supply and their wastes by visiting 2 days in a week. Concurrently, VW of cucumber, bitter gourd, spotted gourd, brinjal, pumpkin, potato, tomato, ladies finger, and snake gourd representing 0.21, 0.18, 0.17, 0.16, 0.09, 0.07, 0.06, 0.03, and 0.02 as fresh fractions, respectively were blended, dried and stored while adding rice polish and common salt at 200 and 20 g/kg DM, respectively; it was tested in bulls as an ingredient of concentrate mixture. Four dietary groups, each of 6 bulls, with initial average live weight (LW) of 85.47 ± 17 kg, were fed fresh German grass (Echinochloa polystachya) ad libitum supplemented with 4 different concentrates containing 0, 10%, 20% and 30% VWP at the rate of 1% of LW for 89 days. The availability of VW biomass of the market was 42.51 t/d and recycling of them as feed, instead of using landfills, might reduce annual methane emission by 0.43 Gg. The inclusion of VWP in the diet up to 9.7% of DM, or 0.30% of LW of bulls showed no significant effect on the DM intake, digestibility, growth performance and health status of bulls. The dietary DM intake represented 3.10%, 3.09%, 3.20% and 3.14% of LW resulting in daily gain of 302, 300, 312 and 344 g, respectively. The digestibility of DM of diets was 56.9%, 62.8%, 62.8% and 63.4%, respectively. It was concluded that VWP may be included at a level of 9.7% of the diet (DM basis) or 0.30% of LW of bulls.

Analysis of the plant composition of manatee (Trichechus manatus manatus) faeces in a lake in south‐eastern Mexico

Abstract The Antillean manatee (Trichechus manatus manatus) is a species at risk of extinction. Its diet in freshwater environments has been scarcely studied in Mexico, despite its significance for managing populations and habitat. The diet of Antillean manatees inhabiting the Natural Protected Area of Laguna de las Ilusiones, in Villahermosa, Tabasco, Mexico, was studied during the rainy season. A microhistological analysis was conducted on 51 manatee faecal samples. The cuticle and epidermis of 35 plant species present in vegetation patches used as foraging grounds by the Antillean manatee were described. In total, 223 plant fragments belonging to 11 families and 25 vascular plant taxa were identified. Echinochloa polystachya had the highest frequency (70.6%). Plant richness per faecal sample varied between one and eight plant species. This manatee population feeds mainly on grass. The plant species found coincide with those reported in other studies on sirenian diets. However, 11 new plant species consumed by manatees were recorded. This is the most comprehensive study to date in river systems in Mexico on the botanical richness of manatee faeces. The information provided here can be applied to decision‐making on the conservation of the Antillean manatee and its critical habitat.

Pre and Post-natal Nutrition of Ewes on the Performances of Native Bengal Ewes and Their Lambs

The aim of the study is to determine the effects of different plane of nutrition during late pregnancy to lactation on the performances of ewes and their offspring to weaning. About 36 native Bengal ewes of last 7 weeks gestation were randomly assigned to four different groups (T0, T1, T2, T3). The T0, T1, T2 and T3 groups were supplemented a concentrate mixture at 0.0, 1.0, 1.5 and 2.0% of their body weight, respectively. Chopped German grass (Echinochloa polystachya) was provided as basal forages to ewes and a creep mixture (20 g/lamb/day) to the lambs from 2 weeks of age with a weakly increase of 10 g/lamb. The results shown that ewes dry matter intake (p < 0.01), milk yield (p < 0.05), days open (p < 0.01), live weight gain before lambing (p < 0.01) and at weaning (p < 0.01) and weight recovery from late gestation to weaning (p < 0.05) improved with high plane of nutrition. Higher weight recovery found in T2 group. Litter size had an effect on (p < 0.01) all weight traits of lambs and ewes milk yield. Sex of lamb also affects (p < 0.05) the weaning weight and daily gain of lambs.

Mobility and Translocation of Heavy Metals from Mine Tailings in Three Plant Species after Amendment with Compost and Biosurfactant

An experiment was performed to determine the effects of mine tailings alone mixed with compost or with compost plus crude biosurfactant on the accumulation of heavy metals (Pb, Zn, Cu, Cr, Cd, and Ni) in Acacia retinodes, Nicotiana glauca, and Echinochloa polystachya. The plants were grown in soil, mine tailings, and mine tailings containing compost over a period of seven and five months for shrubs or grass, respectively. The plants Acacia retinodes and Nicotiana glauca grown in mine tailings containing compost showed increases in dry biomass (from 62 to 79%) compared with plants in only tailings. Heavy metals accumulated in the roots and leaves showed high translocation rates of Cr in N. glauca, Cd in A. retinodes, and Ni in E. polystachya. Concentrations of heavy metals in the three plants irrigated with crude biosurfactant were not significantly different from those irrigated with water. Zn and Cd fractions within mine tailings containing compost were bound to carbonate, Pb was bound to residues, and Cu was bound to Fe-oxides. Cd had the highest mobility factor followed in order by Zn, Pb, and Cu. The elevated concentrations of Pb in roots and the low translocation rate for N. glauca and A. retinodes indicate that they are suitable for phytostabilizing Pb and Zn.

Performance of a system of natural wetlands in leachate of a posttreatment landfill

Phytoremediation is an emerging technology in landfill leachate posttreatment. The evaluation of a system composed of three natural wetlands. The wetlands vegetation cover was monitored during 2 years by estimating the coverage area of the macrophytes. Chemical analyzes of the effluent were conducted monthly. The monitoring and identification of macrophytes indicated that the vegetation structure was represented by four species of higher relative cover: Pistia stratiotes L. (water lettuce), Echinochloa polystachya (Kunth) Hitchc. (creeping river grass), Eichhornia crassipes (Mart.) Solms (water hyacinth) and Alternanthera philoxeroides (Mart.) Griseb. The system of natural wetlands had an average efficiency of 75 % for biochemical oxygen demand, 63 % for chemical oxygen demand, 84 % for ammoniacal nitrogen, 89 % for total nitrogen and 70 % for phosphorus. The concentrations of heavy metals in the roots, as well as in the branches of E. crassipes and E. polystachya, lead us to the conclusion that such species perform phytoextraction for Cd and Pb accumulating the metals in the biomass. The results show that this is a viable alternative that can be associated with forms of conventional treatment of leachate, such as the treatment with aerobic and facultative ponds.

Abdômen agudo em equídeos no semiárido da região nordeste do Brasil

Foram revisados os casos de abdômen agudo de origem gastrintestinal em equídeos atendidos no Hospital Veterinário da Universidade Federal de Campina Grande, em Patos, Paraíba. No período de janeiro de 2001 a dezembro de 2010. Setenta (4,5%) do total de 1542 equídeos atendidos no período apresentaram quadro clínico de cólica, sendo 60 equinos, cinco muares e cinco asininos. A compactação de cólon maior foi a causa mais frequente de cólica, diagnosticada em 37,14% dos casos, seguida por compactação de cólon menor (10%) e corpo estranho de cólon menor (7,14%). Em quatro casos as cólicas foram causadas pela presença de fitobezoares no intestino grosso, sendo dois deles associados ao consumo de vagens de Prosopis juliflora. Em cinco casos foi observada a presença de corpos estranhos no cólon menor e em um caso os corposestranhos foram encontrados no cólon maior, sendo principalmente sacos plásticos. As lesões estrangulantes do intestino delgado foram observadas em quatro casos. Outras causas foram cólica espasmódica (dois casos por parasitose e dois por ingestão de resíduos domiciliares), sobrecarga gástrica (três casos) e deslocamento de cólon maior que foi diagnosticado em dois animais. Laceração de cólon menor, torção de ceco, compactação de ceco e timpanismo por consumo de Manihot esculenta foram diagnosticados em uma única ocasião. O principal fator de risco para o desenvolvimento de cólicas foi o consumo de Pennisetum purpureum, Brachiaria decumbens, Sorghum spp. ou Echinochloa polystachya picados manualmente ou em picotadeira ou triturados em forrageira (OR=4,03; P=0,007). Como resultado da baixa qualidade dos alimentos ingeridos, a frequência dos atendimentos de equídeos portadores de cólica foi significativamente maior no segundo semestre (época da seca na região estudada) (OR=2,61; P&lt;0,01). Concluiu-se que a oferta de volumoso de baixa qualidade na seca contribui para a alta frequência de casos de cólica e que o manejo alimentar tem um papel importante na ocorrência da doença e, por isso, a sua melhoria pode influenciar positivamente na redução do número de casos de cólica em equídeos no semiárido nordestino.

Time of exposure and oil dosage affecting biomass production of the Amazonian semi-aquatic grass Echinochloa polystachya

Abstract The effects of Urucu crude oil on growth and biomass production of Echinochloa polystachya were studied experimentally. Young plants contaminated with 5 oil doses (0 to 2.64 l.m-2) were monitored at 1, 5, 10, 15 and 20 days after exposure. A significant reduction was observed in leaf humidity and the ratio of live aerial/ total biomass related to the increase in oil dosage. Increased exposition time caused a reduction in the number of leaves, aerial biomass, proportion of live aerial/total biomass, total biomass, and an increase of dead aerial biomass. However, root biomass and leaf length were not affected by exposure to oil. The low tolerance of E. polystachya to Urucu crude oil has lead to the mortality of 90% of the plant population in 20 days at the 2.64 l treatment. The death of young individuals of E. polystachya by relatively low dosages of Urucu oil indicates that, in the case of an oil spill in the Amazon varzea, this species would be severely affected, endangering, consequently, the entire environment.

O período da contaminação com petróleo influencia a rebrota de Echinochloa polystachya (H.B.K.) Hitchcock em solo de várzea da Amazônia Central?

Diversos fatores podem influenciar o impacto do petróleo no meio ambiente. No entanto, embora seja sabido que o efeito dos poluentes pode mudar ao longo do ano de acordo com as variações sazonais em parâmetros ambientais, esse efeito é pobremente estudado na região tropical. Foi estudado o efeito do petróleo de Urucu sobre o rebrotamento e crescimento de Echinochloa polystachya durante 63 dias, em plantios estabelecidos em casa de vegetação em dois períodos do ano, "A" (julho a setembro) e "B" (setembro a novembro). Os propágulos foram plantados em frascos com 2 L de solo contaminado pela mistura de 6 dosagens de petróleo, distribuídas entre 0 e 0,231 L óleo m-2 de solo. Em resposta ao aumento da dosagem do petróleo houve diminuição da biomassa total, da biomassa aérea viva/total, da biomassa aérea, do comprimento das folhas e do número de folhas. O período de plantio influenciou a resposta das plantas à dosagem aplicada o que foi positivamente correlacionado a alterações climáticas, com efeitos negativos acentuados no período "B", de temperaturas mais elevadas. Pode-se concluir que o período de exposição influencia a propagação vegetativa e crescimento das plantas jovens, sendo um derrame no período de temperaturas mais altas mais prejudicial para essa espécie.

Fractions of carbohydrates and of nitrogenous compounds of tropical grasses at different cutting ages

It was evaluated by the Cornell System carbohidrates fractions and nitrogenous compounds of the following grasses at the cutting ages of 14, 28, 42, and 56 days: nilo grass (Acroceras macrum), angola grass (Brachiaria purpurascens), aleman grass (Echinochloa polystachya), limpo grass (Hemarthria altíssima), setaria grass (Setaria anceps), tanner grass (Brachiaria arrecta), and tifton-85 grass (Cynodon spp). The experiment was carried out in a complete randomized block design, in a split plot arrangement in a way that the grasses were evaluated in the plots and the ages of cut in the split-plots. The age of cutting had an effect on the composition of the studied grasses. In most of the grasses, total carbohydrate levels, non-fibrous carbohydrates and A+B1 fraction carbohydrates increased linearly according to the age of cutting. The potentially degradable fraction of carbohydrates (fraction B2) showed a quadratic behavior according to the cutting ages for all grasses. The C fraction of the carbohydrates in tifton-85 grass linearly increased with the age but it did not increase significantly for the other grasses. In setaria grass, the intermediate levels of B2 and B3 nitrogenous fractions were high, which might represent a potential source of protein for ruminal degradation and for the small intestine. Except for setaria grass, all studied grasses show similar values of the A, B1, B2 and B3 nitrogenous fractions.