Evaluation of connected clonal growth of Solidago chilensis as an avoidance mechanism in copper-polluted soils.

Plant resistance to metals can be achieved by two strategies, tolerance and avoidance. Although metal tolerance has been broadly studied in terrestrial plants, avoidance has been less considered as a strategy to cope with soil metal pollution. Avoidance may be an effective alternative in herbaceous plants with connected clonal growth in environments having high heterogeneity in soil micro-spatial distribution of available metals and other soil conditions (i.e. organic matter). In this study, we performed a laboratory experiment on clonal growth of Solidago chilensis when exposed to copper-spiked soils (800 mg kg-1) at different depths (0, 2, 5 and 8 cm depth), with (20%) and without addition of organic matter to mimic contrasting microhabitats found at smelter hinterlands (i.e. open bare ground and microhabitats below shrubs). Results showed that plants grown in the 2 cm-depth Cu-spiked soils were able to growth and produce ramets and rhizomes. However, increased Cu uptake of plants determined phytotoxic effects and a reduction in clonal spread in the 5 cm- and 8 cm-depth Cu-spiked soils. Addition of organic matter to the Cu-spiked soil layers allowed clonal spread. Considering that ramet and rhizome production is decreased but not inhibited when copper pollution is restricted to the uppermost soil layer (2 cm depth) and that organic matter eliminated soil copper toxicity allowing normal clonal spread, connected clonal growth may be an effective avoidance mechanism of Solidago chilensis, particularly in environments with high heterogeneity in micro-spatial distribution of metals and organic matter in the soil profile and between microhabitats.

Evaluation of arrowroot agronomic performance (Maranta arundinacea) Seta intercropped with sunn hemp / Avaliação do desempenho agronômico da araruta (Maranta arundinacea) Seta consorciada com crotalária

Because it is an unconventional vegetable, arrowroot is appropriate for family farming; there is a need to find alternative ways to make its growing more sustainable, however. The objective of this study was to evaluate the productive performance of rhizomes and starch of arrowroot Seta intercropped with crotalaria. The experiment consisted of four treatments, corresponding to three harvest for crotalaria intercropped with arrowroot (90, 120 and 150 days after sowing) plus single cultivation of arrowroot. The experiment used a complete randomized block design with four replications. Mass production of crotalaria, macro and micronutrients contents in the cut material and infestation by invasive plants were evaluated at each harvest. At the harvest of arrowroot, productivity and format of rhizomes classes, macro and micronutrient contents were evaluated, and the export of nutrients and production of starch by rhizomes were estimated. The hasvests carried out at 120 and 150 DAS, despite propagating the highest values of weight and nutrients, provided lower yields of total, large rhizomes, and starch. Crotalaria hasvested at 90 DAS provided values higher than the cuts performed on 120 and 150 DAS for most evaluated variables, not differing from control, including starch. The intercropping provided less infestation by invasive plants. The intercropping between crotalaria and...

A araruta, por ser uma hortaliça não convencional é apropriada a exploração familiar, havendo necessidade de se encontrar formas alternativas para tornar seu o cultivo mais sustentável. Objetivou-se avaliar o desempenho produtivo de rizomas e de amido da araruta Seta cultivada em consórcio com a crotalária. O experimento constou de quatro tratamentos, correspondentes a três épocas de corte da crotalária associada com a araruta (90, 120 e 150 dias após a semeadura) mais o monocultivo da araruta. Utilizou-se o delineamento experimental de blocos casualizados, com quatro repetições. Nos cortes, avaliaram-se produção de massa de crotalária, conteúdo de macro e de micronutrientes no material cortado e a infestação por plantas invasoras. Na colheita da araruta, avaliaram-se produtividade e formato das classes de rizomas, teor de macro e micronutrientes, estimadas a exportação de nutrientes e a produção de amido pelos rizomas. Os cortes realizados aos 120 e 150 DAS, embora tenham veiculado maiores valores de massa e de nutrientes, proporcionou menores produtividades de rizomas grandes, total e de amido. O corte da crotalária aos 90 DAS proporcionou valores superiores aos cortes realizados aos 120 e 150 DAS para maioria das variáveis avaliadas, não diferindo do controle, inclusive para o amido. O consórcio proporcionou menor infestação por plantas invasoras. É agronomicamente viável...

Evaluation of arrowroot agronomic performance (Maranta arundinacea) Seta intercropped with sunn hemp / Avaliação do desempenho agronômico da araruta (Maranta arundinacea) Seta consorciada com crotalária

Because it is an unconventional vegetable, arrowroot is appropriate for family farming; there is a need to find alternative ways to make its growing more sustainable, however. The objective of this study was to evaluate the productive performance of rhizomes and starch of arrowroot Seta intercropped with crotalaria. The experiment consisted of four treatments, corresponding to three harvest for crotalaria intercropped with arrowroot (90, 120 and 150 days after sowing) plus single cultivation of arrowroot. The experiment used a complete randomized block design with four replications. Mass production of crotalaria, macro and micronutrients contents in the cut material and infestation by invasive plants were evaluated at each harvest. At the harvest of arrowroot, productivity and format of rhizomes classes, macro and micronutrient contents were evaluated, and the export of nutrients and production of starch by rhizomes were estimated. The hasvests carried out at 120 and 150 DAS, despite propagating the highest values of weight and nutrients, provided lower yields of total, large rhizomes, and starch. Crotalaria hasvested at 90 DAS provided values higher than the cuts performed on 120 and 150 DAS for most evaluated variables, not differing from control, including starch. The intercropping provided less infestation by invasive plants. The intercropping between crotalaria and...(AU)

A araruta, por ser uma hortaliça não convencional é apropriada a exploração familiar, havendo necessidade de se encontrar formas alternativas para tornar seu o cultivo mais sustentável. Objetivou-se avaliar o desempenho produtivo de rizomas e de amido da araruta Seta cultivada em consórcio com a crotalária. O experimento constou de quatro tratamentos, correspondentes a três épocas de corte da crotalária associada com a araruta (90, 120 e 150 dias após a semeadura) mais o monocultivo da araruta. Utilizou-se o delineamento experimental de blocos casualizados, com quatro repetições. Nos cortes, avaliaram-se produção de massa de crotalária, conteúdo de macro e de micronutrientes no material cortado e a infestação por plantas invasoras. Na colheita da araruta, avaliaram-se produtividade e formato das classes de rizomas, teor de macro e micronutrientes, estimadas a exportação de nutrientes e a produção de amido pelos rizomas. Os cortes realizados aos 120 e 150 DAS, embora tenham veiculado maiores valores de massa e de nutrientes, proporcionou menores produtividades de rizomas grandes, total e de amido. O corte da crotalária aos 90 DAS proporcionou valores superiores aos cortes realizados aos 120 e 150 DAS para maioria das variáveis avaliadas, não diferindo do controle, inclusive para o amido. O consórcio proporcionou menor infestação por plantas invasoras. É agronomicamente viável...(AU)

Bacillus methylotrophicus M4-96 isolated from maize (Zea mays) rhizoplane increases growth and auxin content in Arabidopsis thaliana via emission of volatiles.

Plant growth-promoting rhizobacteria stimulate plant growth and development via different mechanisms. In this study, we characterized the effect of volatiles from Bacillus methylotrophicus M4-96 isolated from the maize rhizosphere on root and shoot development, and auxin homeostasis in Arabidopsis thaliana. Phytostimulation occurred after 4 days of interaction between M4-96 and Arabidopsis grown on opposite sides of divided Petri plates, as revealed by enhanced primary root growth, root branching, leaf formation, and shoot biomass accumulation. Analysis of indole-3-acetic acid content revealed two- and threefold higher accumulation in the shoot and root of bacterized seedlings, respectively, compared to uninoculated plants, which was correlated with increased expression of the auxin response marker DR5::GUS. The auxin transport inhibitor 1-naphthylphthalamic acid inhibited primary root growth and lateral root formation in axenically grown seedlings and antagonized the plant growth-promoting effects of M4-96. Analysis of bacterial volatile compounds revealed the presence of four classes of compounds, including ten ketones, eight alcohols, one aldehyde, and two hydrocarbons. However, the abundance of ketones and alcohols represented 88.73 and 8.05%, respectively, of all airborne signals detected, with acetoin being the main compound produced. Application of acetoin had a different effect from application of volatiles, suggesting that either the entire pool or acetoin acting in concert with another unidentified compound underlies the strong phytostimulatory response. Taken together, our results show that B. methylotrophicus M4-96 generates bioactive volatiles that increase the active auxin pool of plants, stimulate the growth and formation of new organs, and reprogram root morphogenesis.

Effect of the combined addition of Zn and Pb on partitioning in sediments and their accumulation by the emergent macrophyte Schoenoplectus californicus.

Wetlands usually provide a natural mechanism that diminishes the transport of toxic compounds to other compartments of the ecosystem by immobilization and accumulation in belowground tissues and/or soil. This study was conducted to assess the ability of Schoenoplectus californicus growing in natural marsh sediments, with zinc and lead addition, to tolerate and accumulate these metals, taking account of the metal distribution in the sediment fractions. The Zn and Pb were mainly found in available (exchangeable) and potentially available (bound to organic matter) forms, respectively. The absorption of Zn and Pb by plants increased in sediments with added metals. Both metals were largely retained in roots (translocation factor < 1). Lead rhizome concentrations only increased significantly in treatments with high doses of metal independently of added Zn. The addition of Zn increased its concentration in roots and shoots significantly, while its concentration in rhizomes only increased when both metals were added together. Zinc concentration in shoots did not reach the toxic level for plants. Zinc and Pb concentrations in roots were high, but they were not sufficient to reduce biomass growth.

Seeds' physicochemical traits and mucilage protection against aluminum effect during germination and root elongation as important factors in a biofuel seed crop (Ricinus communis).

We determined the length, volume, dry biomass, and density in seeds of five castor bean cultivars and verified notable physicochemical trait differences. Seeds were then subjected to different toxic aluminum (Al) concentrations to evaluate germination, relative root elongation, and the role of root apices' rhizosphere mucilage layer. Seeds' physicochemical traits were associated with Al toxicity responses, and the absence of Al in cotyledons near to the embryo was revealed by Al-hematoxylin staining, indicating that Al did not induce significant germination reduction rates between cultivars. However, in the more sensitive cultivar, Al was found around the embryo, contributing to subsequent growth inhibition. After this, to investigate the role of mucilage in Al tolerance, an assay was conducted using NH4Cl to remove root mucilage before or after exposure to different Al concentrations. Sequentially, the roots were stained with hematoxylin and a quantitative analysis of staining intensity was obtained. These results revealed the significant contribution of the mucilage layer to Al toxicity responses in castor bean seedlings. Root growth elongation under Al toxicity confirmed the role of the mucilage layer, which jointly indicated the differential Al tolerance between cultivars and an efficient Al-exclusion mechanism in the tolerant cultivar.

Agro-economic yield of taro clones in Brazil, propagated with different types of cuttings, in three crop seasons.

The experimental studies were conducted in 2007-2008, 2008-2009 and 2009-2010 crop seasons, in order to know the agro-economic yield of 'Chinês' and "Macaquinho" taro clones, propagated using huge, extra, large, medium, small and tiny cormels. The harvest was done on average on 202 days after planting, in three crop seasons. Based on the joint analysis of variance carried out, it was observed that taro clones showed significant differences in the yield of fresh and dry weight of leaves, cormels, and commercial and non-commercial comels; besides, there were significant differences in yield of a crop season to another and the size of the cuttings induced significant differences in yield. In the conditions that the experiments were conducted, and considering the highest average yield of fresh weight of commercial cormels (28.69 t.ha-1) and highest net income (US $14,741.14) correspondent to the three crop seasons, it is recommended to cultivate 'Macaquinho' clone using small cuttings in propagation.

Caracterização anatômica e fitoquímica de folhas e rizomas de Hedychium coronarium J. Kõnig (Zingiberaceae) / Anatomical and phytochemical characterization of leaves and rhizomes from Hedychium coronarium J. Kõnig (Zingiberaceae)

Devido a grande potencialidade na utilização de Hedychium coronarium, na medicina popular e também como biorremediadora no tratamento de efluentes, objetivou-se uma diagnose dos órgãos, folha e rizoma, para elucidar resultados estruturais e fitoquímicos. A folha é anfiestomática, com predominância de estômatos na face abaxial. Em ambas as superfícies foliares há projeções de cera epicuticular sobre as paredes anticlinais das células epidérmicas. O mesofilo dorsiventral apresenta hipoderme multisseriada (3 camadas) em ambos os lados. O parênquima clorofiliano é diferenciado em paliçádico (1-2 camadas) e lacunoso (4-5 camadas) com muitos espaços intercelulares e ocorrência de idioblastos cristalíferos. Na nervura central, o aerênquima ocorre em único arco na região abaxial. Os feixes vasculares distribuem-se aleatoriamente e são de diferentes tamanhos, pequenos, médios e grandes, envolvidos por fibras. Os feixes menores localizam-se no lado abaxial da nervura. A triagem fitoquímica das folhas mostrou a presença de saponinas e ausência de taninos, antraquinonas, alcalóides e flavonóides. Por meio de Cromatografia em Camada Delgada foram identificadas as presenças de cariofileno e mirceno no óleo essencial bruto obtido a partir das folhas de H. coronarium.

Due to the great potentiality regarding the use of Hedychium coronarium in folk medicine and also as a bioremediator in effluent treatment, this study aimed to diagnose leaf and rhizome in order to elucidate structural and phytochemical results. Hedychium coronarium leaf is amphistomatal, with predominance of stomata on the abaxial surface. On both leaf surfaces, there are epicuticular wax projections over the anticlinal walls from epidermal cells. The dorsiventral mesophyll presents multiseriate (3 layers) hypoderm on both sides. The chlorophyllian parenchyma is differentiated into palisade (1-2 layers) and spongy (4-5 layers) with many intercellular spaces and some crystalliferous idioblasts. In the midrib, the aerenchyma occurs in a single arc on the abaxial surface. The vascular bundles are randomly distributed and present different sizes: small, medium and large, involved by fibers. The smallest bundles are found on the abaxial rib surface. The leaf phytochemical analysis showed the presence of saponins and lack of tannins, anthraquinones, alkaloids and flavonoids. Using thin-layer chromatography, the presence of caryophyllene and myrcene was detected in the crude essential oil obtained from H. coronarium leaves.

Rhizosphere characteristics of two arsenic hyperaccumulating Pteris ferns.

Better understanding of the processes controlling arsenic bioavailability in the rhizosphere is important to enhance plant arsenic accumulation by hyperaccumulators. This greenhouse experiment was conducted to evaluate the chemical characteristics of the rhizosphere of two arsenic hyperaccumulators Pterisvittata and Pterisbiaurita. They were grown for 8 weeks in rhizopots containing arsenic-contaminated soils (153 and 266 mg kg(-1) arsenic). Bulk and rhizosphere soil samples were analyzed for water-soluble As (WS-As) and P (WS-P), pH, and dissolved organic carbon (DOC). Comparing the two plants, P.vittata was more tolerant to arsenic and more efficient in arsenic accumulation than P.biaurita, with the highest frond arsenic being 3222 and 2397 mg kg(-1). Arsenic-induced root exudates reduced soil pH (by 0.74-0.92 units) and increased DOC concentrations (2-3 times) in the rhizosphere, resulting in higher WS-P (2.6-3.8 times higher) compared to the bulk soil. Where there was no difference in WS-As between the rhizosphere and bulk soil in soil-153 for both plants, WS-As in the rhizosphere was 20-40% higher than those in bulk soil in soil-266, indicating that the rate of As-solubilization was more rapid than that of plant uptake. The ability to solubilize arsenic via root exudation in the rhizosphere and the ability to accumulate more P under arsenic stress may have contributed to the efficiency of hyperaccumulator plants in arsenic accumulation.

Phytoremediation of two types of sediment contaminated with Zn by Schoenoplectus americanus.

The effect of different sediments on growth, Zn uptake, Zn plant distribution, and morphometric variables of Schoenoplectus americanus were investigated under controlled conditions. Two types of sediments were assayed: from a large natural levee (LS) and alluvial sediments (AS), the former with lower organic matter (OM) and nutrients content than AS, without and with added Zn (2500 microg Zn/g air-dry sediment). Zinc partition in sediment was determined. Increases in water conductivity and Zn concentrations in water and sediments were observed in artificially contaminated treatments. Plants showed a lower above ground growth rate, height, and width of shoots, and a higher Zn concentration in shoots and rhizomes. In the contaminated treatments, AS treatment showed lower Zn concentration in water and higher Zn concentration in sediments (total, exchangeable, and OM fractions) than LS treatment, due to Zn displacement from floodwater to sediments. The presence of a high level of OM and nutrients also increased aboveground biomass growth, whereas it decreased Zn concentration in shoots. Although the translocation factor increased with Zn addition, it was lower in AS treatment Sediments of AS treatments are a suitable environment for growth of S. americanus, which partially compensates the toxic effects of Zn. Our results provide an encouraging basis for planning larger scale experiments to test the role of OM and nutrients in improving phytoremediation.

Comparative study of differentiation levels and valepotriate content of in vitro cultures and regenerated and wild plants of Valeriana edulis ssp.procera.

Valepotriate content levels in samples of in vitro cultures of Valeriana edulis ssp. procera were compared with those of roots and rhizomes of wild plants in the reproductive stage. Rhizomes and roots of regenerated and wild plants showed a similar valepotriate content. The data obtained support the hypothesis that valepotriate production in V. edulis spp. procera is closely related to rhizome and root differentiation. The large-scale propagation of this endangered plant may offer an attractive alternative for its production for medicinal purposes.