Yield and quality of elephant grass biomass produced in the cerrados region for bioenergy

The objective of this study was to evaluate the performance of two genotypes of elephant grass, fertilized with and without N, for biomass production for energy use under the edaphoclimatic conditions of the Cerrado. The genotypes Roxo and Paraíso, grown in a field experiment in a Latosol in the Cerrado region were evaluated for biomass yield, nitrogen accumulation, C:N and stem:leaf ratios, fibre, ash and P and K contents and calorific value. The accumulated dry biomass ranged from 30 to 42 Mg ha-1 and showed no response to nitrogen fertilization with the lowest biomass obtained by the genotype Paraíso and the highest by Roxo. The total N accumulation followed the same pattern as for dry matter, ranging from 347 to 539 kg N ha-1. C:N and stem:leaf ratio of the biomass produced did not vary with treatments. The fibre contents were higher in genotype Paraíso and the highest levels of ash in the genotype Roxo. The K content in the biomass was higher in genotype Roxo and P did not vary between genotypes. The calorific value averaged 18 MJ kg-1 of dry matter and did not vary with the levels of N in leaves and stems of the plant. Both genotypes, independent of N fertilization, produced over 30 Mg ha-1 of biomass under Cerrado conditions.

Assimilate partitioning and phytotoxicity in soybean plants treated with herbicides

To investigate the effects of trifluralin, chlorimuron and clomazone on morphology and assimilate partitioning during soybean development, plants were grown in a greenhouse and sampled at 14-day intervals. Clomazone reduced stem and leaf dry matter accumulation at 14 days after emergence (DAE), while trifluralin and chlorimuron reduced plant part dry matter accumulation up to 28 DAE. The number of leaves, plant height, mass and number of pods and seeds, and the shoot/root ratio were not influenced by the herbicides. Roots, stems and leaves were the preferred sinks up to the R2 growth stage, while pods and developing seeds became the preferred sinks later. This order was not altered by the herbicides.

Allelopathic effects of Rhynchosia capitata on germination and seedling growth of mungbean

Experiments were conducted to evaluate the allelopathic influence of Rhynchosia capitata on germination and seedling growth of mungbean (Vigna radiate) along with identification of the phytotoxic substances responsible for this activity. Water extracts of root, shoot, leaf, fruit and whole plant were prepared by soaking them in water in a ratio of 1:20 (w/v) for 24 h. All the extracts affected germination and seedling growth of mungbean, but higher inhibition was seen with R. capitata leaf water extracts. A linear decrease in the germination characteristics of mungbean was observed with the decrease in the concentration of leaf extract from 5% to 1%. The soil-incorporated residues (1-4% w/w) of R. capitata stimulated the growth of root and hypocotyl at low concentrations, while it inhibited their growth at higher concentrations. Rhynchosia capitata soil-incorporated residues (4% w/w) significantly reduced the seedling vigour index of mungbean in addition to their significant effect on total germination. A significant amount of water-soluble phenolic acids were found in R. capitata plant extracts. The content of total phenolic acids was higher in the leaf extract compared to that of the stem, fruit or root extracts. Two phenolic acids including vanillic acid and 4‑(hydroxymethyl) benzoic acid were found in R. capitata leaf extracts.

The Allelopathic Effect of Eucalyptus Leaf Extract on Grass Forage Seed

This study aimed to evaluate the allelopathic effect of various concentrations of an aqueous extract of eucalyptus leaves on Urochloa decumbens and Panicum maximum seeds. The extract was prepared from Eucalyptus urograndis leaves that were milled and mixed with distilled water in a 1:9 milled leaves: water ratio to obtain an extract with a defined concentration of 100%. In addition, dilutions of 50%, 25% and 12.5% were prepared, and a 0% dilution was used as a control. The experiment followed a completely randomized design, with four replicates, each of 50 seeds of U. decumbens and 50 seeds of P. maximum, arranged on filter paper moistened with each concentration of extract in a Gerbox plastic box. The results demonstrated the allelopathic potential of E. urograndis aqueous extracts applied to the seeds of U. decumbens and P. maximum. The 50% and 100% concentrations of leaf extract most strongly inhibited the germination, vigor and seedling growth of U. decumbens and P. maximum. The germination speed index and the root length were the characteristics that were most affected by the potentially allelopathic substances contained in the eucalyptus extracts at all concentrations.

Flooding effects in seedlings of Cytharexyllum myrianthum Cham. and Genipa americana L.: responses of two neotropical lowland tree species

Six-month-old seedlings of Cytharexyllum myrianthum and Genipa americana, two common tree species in different flood-prone areas in Brazil, were flooded for up to 90 days to compare their survival and growth responses under these conditions. Seedlings of both species were found to be relatively tolerant to flooding but growth responses changed according to treatment and plant species. Growth of G. americana was reduced by flooding, showing a decrease in root and leaf dry mass, root/shoot ratio and height, without showing any adaptive morphological changes. On the other hand, growth of C. myrianthum seedlings was stimulated under flooding conditions, showing an increase in root dry mass, root/shoot ratio, height, stem diameter and some morphological changes in roots and stems, i.e., development of new roots and stem base hypertrophy. These results could be regarded as an experimental corroboration of the field observations, showing that these species could be indicated for restoration programs of some Neotropical wetlands.

Growth and leaf demography of two Cecropia species

Allometry, growth and leaf demography of two Cecropia species, one with ant mutualist (C. glazioui) and another without it (C. hololeuca), were studied in an Atlantic Rain Forest area in the State of Rio de Janeiro, SE Brazil. Stem diameter was allometrically related to height in both species. Cecropia glazioui showed higher annual growth rates and longer internodes than C. hololeuca. Leaf phenology showed a seasonal pattern in both species, but the number of leaves on each plant was more variable along the year in C. hololeuca than in C. glazioui. Survivorship curves for leaves were intermediate between Deevey's Type I and Type II curves, with young leaves of C. glazioui showing a greater survival rate and life expectancy than those of C. hololeuca. Low variability in leaf production throughout the year and high survival rate for young leaves of C. glazioui may be characteristics related to its association with ants.

Factors associated with bacteremia due to multidrug-resistant Gram-negative bacilli in hematopoietic stem cell transplant recipients

The epidemiology of bacteremia developing during neutropenia has changed in the past decade, with the re-emergence of Gram-negative (GN) bacteria and the development of multidrug resistance (MDR) among GN bacteria. We conducted a case-control study in order to identify factors associated with bacteremia due to multidrug-resistant Gram-negative (MDRGN) isolates in hematopoietic stem cell transplant recipients. Ten patients with MDRGN bacteremia were compared with 44 patients with GN bacteremia without MDR. Bacteremia due to Burkholderia or Stenotrophomonas sp was excluded from analysis (3 cases), because the possibility of intrinsical resistance. Infection due to MDRGN bacteria occurred in 2.9% of 342 hematopoietic stem cell transplant recipients. Klebsiella pneumoniae was the most frequent MDRGN (4 isolates), followed by Pseudomonas aeruginosa (3 isolates). Among non-MDRGN, P. aeruginosa was the most frequent agent (34%), followed by Escherichia coli (30%). The development of GN bacteremia during the empirical treatment of febrile neutropenia (breakthrough bacteremia) was associated with MDR (P < 0.001, odds ratio = 32, 95% confidence interval = 5_190) by multivariate analysis. Bacteremia due to MDRGN bacteria was associated with a higher death rate by univariate analysis (40 vs 9%; P = 0.03). We were unable to identify risk factors on admission or at the time of the first fever, but the occurrence of breakthrough bacteremia was strongly associated with MDRGN bacteria. An immediate change in the antibiotic regimen in such circumstances may improve the prognosis of these patients.

Transplantation of muscle-derived stem cells plus biodegradable fibrin glue restores the urethral sphincter in a pudendal nerve-transected rat model

We investigated whether fibrin glue (FG) could promote urethral sphincter restoration in muscle-derived stem cell (MDSC)-based injection therapies in a pudendal nerve-transected (PNT) rat, which was used as a stress urinary incontinence (SUI) model. MDSCs were purified from the gastrocnemius muscles of 4-week-old inbred female SPF Wistar rats and labeled with green fluorescent protein. Animals were divided into five groups (N = 15): sham (S), PNT (D), PNT+FG injection (F), PNT+MDSC injection (M), and PNT+MDSC+FG injection (FM). Each group was subdivided into 1- and 4-week groups. One and 4 weeks after injection into the proximal urethra, leak point pressure (LPP) was measured to assess urethral resistance function. Histology and immunohistochemistry were performed 4 weeks after injection. LPP was increased significantly in FM and M animals after implantation compared to group D (P < 0.01), but was not different from group S. LPP was slightly higher in the FM group than in the M group but there was no significant difference between them at different times. Histological and immunohistochemical examination demonstrated increased numbers of surviving MDSCs (109 ± 19 vs 82 ± 11/hpf, P = 0.026), increased muscle/collagen ratio (0.40 ± 0.02 vs 0.34 ± 0.02, P = 0.044), as well as increased microvessel density (16.9 ± 0.6 vs 14.1 ± 0.4/hpf, P = 0.001) at the injection sites in FM compared to M animals. Fibrin glue may potentially improve the action of transplanted MDSCs to restore the histology and function of the urethral sphincter in a SUI rat model. Injection of MDSCs with fibrin glue may provide a novel cellular therapy method for SUI.

Co-culture of chondrocytes and bone marrow mesenchymal stem cells in vitro enhances the expression of cartilaginous extracellular matrix components

Chondrocytes and bone marrow mesenchymal stem cells (BMSCs) are frequently used as seed cells in cartilage tissue engineering. In the present study, we determined if the co-culture of rabbit articular chondrocytes and BMSCs in vitro promotes the expression of cartilaginous extracellular matrix and, if so, what is the optimal ratio of the two cell types. Cultures of rabbit articular chondrocytes and BMSCs were expanded in vitro and then cultured individually or at a chondrocyte:BMSC ratio of 4:1, 2:1, 1:1, 1:2, 1:4 for 21 days and cultured in DMEM/F12. BMSCs were cultured in chondrogenic induction medium. Quantitative real-time RT-PCR and Western blot were used to evaluate gene expression. In the co-cultures, type II collagen and aggrecan expression increased on days 14 and 21. At the mRNA level, the expression of type II collagen and aggrecan on day 21 was much higher in the 4:1, 2:1, and 1:1 groups than in either the articular chondrocyte group or the induced BMSC group, and the best ratio of co-culture groups seems to be 2:1. Also on day 21, the expression of type II collagen and aggrecan proteins in the 2:1 group was much higher than in all other groups. The results demonstrate that the co-culture of rabbit chondrocytes and rabbit BMSCs at defined ratios can promote the expression of cartilaginous extracellular matrix. The optimal cell ratio appears to be 2:1 (chondrocytes:BMSCs). This approach has potential applications in cartilage tissue engineering since it provides a protocol for maintaining and promoting seed-cell differentiation and function.

The effects of adding picoxystrobin, azoxystrobin and nitrogen to a triazole programme on disease control, flag leaf senescence, yield and grain quality of winter wheat

The effect of adding strobilurins to a triazole (epoxiconazole) fungicide programme on the quality of a range of wheat cultivars was assessed in field experiments in three successive years. Strobilurin was applied at just flag leaf emergence (azoxystrobin) or at the start of stem extension (azoxystrobin or picoxystrobin) and again at flag leaf emergence or at flag leaf emergence and again at ear emergence (azoxystrobin). All strobilurin treatments reduced disease levels, delayed senescence of the flag leaf and consistently increased yields, thousand grain weight and specific weight. Reductions in Hagberg falling number were observed, even by fungicide applications at the start of stem extension, but effects were small compared to the variation among cultivars. Application of fungicide (triazole or strobilurin) before ear emergence increased the amount of blackpoint, but this was partly countered by applying azoxystrobin at ear emergence. The effect of fungicide on protein concentration differed over seasons and cultivar. Where they occurred. small reductions in protein concentration could be compensated for by extra application of nitrogen as foliar urea at anthesis. Foliar urea (40 kg N ha(-1)) applied at anthesis also improved Hagberg failing number and reduced blackpoint in one of the growing seasons. In one season, the effect of foliar urea at anthesis was compared with applications of granular fertiliser at flag leaf emergence. The granular treatment produced grain with more concentrated protein, while the later, foliar application produced higher specific weights. (C) 2003 Elsevier Science Ltd. All rights reserved.

Far-red light filtering by plastic film, greenhouse-cladding materials: effects on growth and flowering in Petunia and Impatiens

Photoselective plastic films with low transmission to far-red (FR) light (700-800 nm) are now available so that plants grown in greenhouses clad with such plastics exhibit reduced stem extension and, consequently, plant height. Here we compare the action of three FR-absorbing polythene films on extension growth of Petunia (Petunia X hybrida) cv. 'Express Blue' and Impatiens walleriana cv. 'Accent Deep Pink' with plants grown under a control polythene film (standard UVI/EVA film). Half of the plants under the control film were treated with a chemical plant growth regulator (PGR; diaminozide, B-Nine) and half were sprayed with water alone. Possible negative effects of such film plastics on flowering, and on fresh and dry weight accumulation, were also quantified. Plants were harvested destructively when all plants in each treatment had reached the first open flower stage. In Petunia, plant height was reduced by all three FR-filtering films and by PGR-treatment. The FR-filtering films giving the highest R:FR ratios also reduced plant height in Impatiens. Leaf number, leaf area and total dry Weight in both species. were greatest in the controls and smallest under films with the lowest PAR transmission. The film giving the highest R:FR ratio and PAR transmission also produced the most compact Petunia plants;, while the film. with. the lowest PAR transmission produced the least compact plants in both species. There was no significant effect of treatments on time to first flower in Impatiens. However, Petunia plants under low PAR transmission films took longer to flower. Plastic-films which filter out FR light to increase the R:FR ratio, combined With high PAR transmission, can therefore be used as an alternative to conventional PGRs.

Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat

Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha−1 several months previously; (ii) silicon fertilization at 100 mg L−1 during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew (B. graminis) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust (P. recondita). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure.

Exposing the myth of the 1:5:200 ratio relating initial cost, maintenance and staffing costs of office buildings

In an attempt to focus clients' minds on the importance of considering the construction and maintenance costs of a commercial office building (both as a factor in staff productivity and as a fraction of lifetime staff costs) there is an often-quoted ratio of costs of 1:5:200, where for every one pound spent on construction cost, five are spent on maintenance and building operating costs and 200 on staffing and business operating costs. This seems to stem from a paper published by the Royal Academy of Engineering, in which no data is given and no derivation or defence of the ratio appears. The accompanying belief that higher quality design and construction increases staff productivity, and simultaneously reduces maintenance costs, how ever laudable, appears unsupported by research, and carries all the hallmarks of an "urban myth". In tracking down data about real buildings, a more realistic ratio appears to depend on a huge variety of variables, as well as the definition of the number of "lifetime" years. The ill-defined origins of the original ratio (1:5:200) describing these variables have made replication impossible. However, by using published sources of data, we have found that for three office buildings, a more realistic ratio is 1:0.4:12. As there is nothing in the public domain about what comprised the original research that gave rise to 1:5:200, it is not possible to make a true comparison between these new calculations and the originals. Clients and construction professionals stand to be misled because the popularity and widespread use of the wrong ratio appears to be mis-informing important investment and policy decisions.

Stomatal conductance and not stomatal density determines the long-term reduction in leaf transpiration of poplar in elevated CO2

Using a free-air CO2 enrichment (FACE) experiment, poplar trees (Populus · euramericana clone I214) were exposed to either ambient or elevated [CO2] from planting, for a 5-year period during canopy development, closure, coppice and re-growth. In each year, measurements were taken of stomatal density (SD, number mm2) and stomatal index (SI, the proportion of epidermal cells forming stomata). In year 5, measurements were also taken of leaf stomatal conductance (gs, lmol m2 s1), photosynthetic CO2 fixation (A, mmol m2 s1), instantaneous water-use efficiency (A/E) and the ratio of intercellular to atmospheric CO2 (Ci:Ca). Elevated [CO2] caused reductions in SI in the first year, and in SD in the first 2 years, when the canopy was largely open. In following years, when the canopy had closed, elevated [CO2] had no detectable effects on stomatal numbers or index. In contrast, even after 5 years of exposure to elevated [CO2], gs was reduced, A/E was stimulated, and Ci:Ca was reduced relative to ambient [CO2]. These outcomes from the long-term realistic field conditions of this forest FACE experiment suggest that stomatal numbers (SD and SI) had no role in determining the improved instantaneous leaf-level efficiency of water use under elevated [CO2]. We propose that altered cuticular development during canopy closure may partially explain the changing response of stomata to elevated [CO2], although the mechanism for this remains obscure.

Genotypic variation in photosynthetic and leaf traits in cocoa

The photosynthetic characteristics of eight contrasting cocoa genotypes were studied with the aim of examining genotypic variation in maximum (light-saturated) photosynthetic rates, light-response curve parameters and water use efficiency. Photosynthetic traits were derived from single leaf gas exchange measurements using a portable infra-red gas analyser. All measurements were conducted in a common greenhouse environment. Significant variation was observed in light-saturated photosynthesis ranging from 3.4 to 5.7 µmol CO2 m-2 s-1 for the clones IMC 47 and SCA 6, respectively. Furthermore, analyses of photosynthetic light response curves indicated genotypic differences in light saturation point and quantum efficiency (i.e. the efficiency of light use). Stomatal conductance was a significant factor underlying genotypic differences in assimilation. Genotypic variation was also observed in a number of leaf traits, including specific leaf area (the ratio of leaf area to leaf weight), chlorophyll concentration and nitrogen content. There was a positive correlation between leaf nitrogen per unit area and light-saturated photosynthesis. Water use efficiency, defined as the ratio of photosynthetic rate to transpiration rate, also varied significantly between clones (ranging from 3.1 mmol mol-1 H2O for the clone IMC 47 to 4.2 mmol mol-1 H2O for the clone ICS 1). Water use efficiency was a negative function of specific leaf area, suggesting that low specific leaf area might be a useful criterion for selection for increased water use efficiency. It is concluded that both variation in water use efficiency and the photosynthetic response to light have the potential to be exploited in breeding programmes.