Crescimento inicial de mandioca submetida à aplicação de herbicidas em pós-emergência

The aim of this study was to evaluate the initial growth of cassava plants after post-emergence application of herbicides. The experiment was carried out in greenhouse, with randomized block design and four replications. Treatments consisted in the application of herbicides 25 days after crop emergence. The herbicides applied were bentazon, clomazone, fomesafen, fluazifop-p-buthyl, glyphosate, nicosulfuron, chlorimuron-ehtyl, sulfentrazone and the fluazifop-p-buthyl + fomesafen, and a treatment without herbicide application. The visual intoxication of cassava plants was evaluated at 7, 14, 21 and 28 days after herbicide application. Thirty-five days after application, we determined the height, stem diameter and dry matter of plants. Sulfentrazone and glyphosate caused the death of cassava. All herbicides caused reduction in stem dry matter, with the exception of fluazifop-p-buthyl. Chlorimuron-ethyl and nicosulfuron caused greater reduction of dry matter accumulation and crop leaf area. The application of herbicides bentazon, nicosulfuron and chlorimuron-ethyl reduced the stem diameter. It is possible to conclude that the herbicide application affected cassava growth, except for fluazifop-p-buthyl application.Objetivou-se com esse trabalho avaliar o crescimento inicial de plantas de mandioca após aplicação de herbicidas em pós-emergência da cultura. O experimento foi realizado em ambiente protegido, no delineamento de blocos casualizados, com quatro repetições. Os tratamentos foram constituídos pela aplicação, aos 25 dias após a emergência a cultura, dos herbicidas bentazon, clomazone, fomesafen, fluazifop-p-buthyl, glyphosate, nicosulfuron, chlorimuron-ehtyl, a mistura fluazifop-p-buthyl + fomesafen e sulfentrazone, além de uma testemunha sem aplicação. A intoxicação visual das plantas de mandioca foi avaliada aos 7, 14, 21 e 28 dias após a aplicação dos herbicidas. Aos 35 dias após a aplicação determinou-se a estatura, diâmetro do caule e a matéria seca das plantas. O sulfentrazone e o glyphosate causaram a morte da mandioca. Todos herbicidas causaram redução da matéria seca do caule, com exceção do fluazifop-p-buthyl. O chlorimuron-ethyl e o nicosulfuron foram os herbicidas que causaram maior redução do acúmulo de matéria seca e da área foliar da cultura. O diâmetro do caule foi reduzido pelos herbicidas bentazon, nicosulfuron e chlorimuron-ethyl. Conclui-se que o crescimento da mandioca foi alterado pela aplicação dos herbicidas, com exceção do fluazifop-p-buthyl

Competitive capability, selectivity of herbicides and rhizospheric microbial activity of Hymenaea courbaril L seedling.

O presente estudo teve por objetivo avaliar mudas de Hymenea courbaril L. (jatob?) quanto: (a) ? capacidade competitiva com plantas consortes e esp?cies daninhas referentes a aloca??o de mat?ria seca, ?rea foliar e concentra??o de macronutrientes; (b) ? seletividade aos herbicidas sulfentrazone e glyphosate e; (c) aos efeitos de diferentes doses de sulfentrazone sobre a atividade microbiana de substratos cultivados com as mudas. Os experimentos foram conduzidos em casa-de-vegeta??o, viveiro de produ??o de mudas e em laborat?rio na Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), Diamantina-MG. No ano de 2009, foram conduzidos dois experimentos sendo os tratamentos compostos pela combina??o de mudas de jatob?, se desenvolvendo isoladamente ou em competi??o com cada uma das seguintes esp?cies Brachiaria humidicola, Brachiaria brizantha, Brachiaria decumbens, Panicum maximum, Cajanus cajan, Canavalia ensiformis e Mucuna aterrima (experimento 1) e Cenchrus echinatus L., Bidens pilosa L., Euphorbia heterophylla L., Solanum americanum Mill e Lolium multiflorum Lam. (experimento 2), mais o cultivo isolado de cada planta daninha e consorte, por 60 dias. Al?m do efeito das plantas nas caracter?sticas de altura e mat?ria seca das plantas de jatob?, avaliou-se o ac?mulo de nitrog?nio, f?sforo e pot?ssio em todas as plantas. Em 2010, tamb?m foram conduzidos dois experimentos sendo os tratamentos compostos por dois herbicidas (glyphosate e sulfentrazone) e cinco doses desses herbicidas (0,00; 0,09; 0,18; 0,35 e 0,70 L ha-1) (experimento 1); cinco doses de sulfentrazone (0,00; 0,04; 0,15; 0,30 e 0,60 L ha-1) e dois tipos de substratos (rizosf?rico e n?o rizosf?rico cultivados com mudas de jatob?) (experimento 2), sendo avaliado o potencial de intoxica??o desses produtos sobre a esp?cie vegetal e a comunidade microbiana rizosf?rica. Observou-se que a competi??o entre as plantas n?o promoveu altera??es na produ??o de mat?ria seca ou ?rea foliar do jatob?. Sobre a conviv?ncia das plantas daninhas com o jatob?, constatou-se efeito positivo no ac?mulo de nutrientes por estas. Os herbicidas estudados apresentaram-se com elevado potencial para uso no controle de plantas daninhas em ?reas de plantios de jatob? em fase inicial de desenvolvimento. Quanto aos indicadores microbiol?gicos, verifica-se que a evolu??o do C-CO2 e o carbono da biomassa microbiana foram sens?veis ? presen?a dos herbicidas podendo constituir ferramentas auxiliares no monitoramento do impacto desses produtos no ambiente.Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011.ABSTRACT The objective of this study was to evaluate Hymenaea courbaril L (jatoba) seedling in relation to: a) the competitive capability with intercropped plants and weed regarding to dry matter allocation, leaf area and macronutrients concentration. b) The selectivity of herbicides sulfentrazone and glyphosate and, c) the effects of different doses of sulfentrazone on microbial activity of substrates cultivated with the seedling. The experiments were conducted in greenhouse, nursery and laboratory of UFVJM. In 2009, two experiments were carried out, being the treatments a combination of jatoba seedling that had developed alone and/or in competition with one of the following species: Brachiaria humidicola, Brachiaria brizantha, Brachiaria decumbens, Panicum maximum, Cajanus cajan, Canavalia ensiformis and Mucuna aterrima (experiment 1) and Cenchrus echinatus L., Bidens pilosa L., Euphorbia heterophylla L., Solanum americanum Mill and Lolium multiflorum Lam. (experiment 2), plus the isolated cultivation of every weed and plant that was intercropped for 60 days. Besides the effects of the weed plants on height and dry matter of jatoba plants, it was assessed the accumulation of nitrogen, phosphorus and potassium in all of plants. In 2010, it is also made two experiments and the treatment was made with two herbicides (glyphosate and sulfentrazone) and five doses of these herbicides (0,00; 0,09; 0,18; 0,35 e 0,70 L ha-1) (experiment 1); five doses of sulfentrazone (0,00; 0,04; 0,15; 0,30 e 0,60 L ha-1) and two types of substrates (rhizospheric and non-rhizospheric cultivated with jatoba seeding) (experiment 2). It was assessed the poisoning potential of these products on vegetal species and the rhizospheric microbial community. It was observed that the competition between the plants did not trigger changes on production of dry matter or leaf area of jatoba. It was verified a positive effect of nutrients accumulation by weed that lived together with jatoba. These herbicides have showed high potential for use on weed control in areas of jatoba planting in initial phase of development. Regarding to microbiological indicators, it was verified that the C-CO2 and microbial biomass carbon evolution was sensitive to the presence of herbicides that be constitute auxiliary tools on monitoring of the impact of these products

Development of eucalyptus and marandu grass in Silvopastoral System

O presente estudo tem o objetivo de quantificar o crescimento de ?rvores de eucalipto (h?brido E. urophylla x E. grandis) e a radia??o fotossinteticamente ativa (RFA) incidente em Sistema Silvipastoril (SSP), verificando o efeito do sombreamento sobre as plantas de capim-marandu (Brachiaria brizantha cv Marandu). A ?rea experimental situa-se no munic?pio de CurveloMG, o sistema agrossilvipastoril foi implantando em local de pastagem degradada, inicialmente composto por tr?s esp?cies ? arb?rea (eucalipto), agr?cola (milho) e forrageira (capim-marandu), todas plantadas na mesma ?poca. O capim-marandu foi avaliado em delineamento de blocos casualizados em esquema fatorial 2 x 4 + 1, totalizando nove tratamentos com quatro repeti??es (blocos). O fator A - dois espa?amentos do cultivo do eucalipto ? 12 x 2 e 12 x 3 metros, e fator B - quatro dist?ncias das forrageiras em rela??o as ?rvores ? 1, 2, 4 e 6 metros. Ap?s a colheita do milho, o sistema passou a ser silvipastoril. Antecedendo as quatro coletas foi realizado um corte de uniformiza??o da forragem, permanecendo a ?rea em per?odo de descanso de cerca de 60 dias. A primeira avalia??o e corte ocorreu em janeiro de 2016 e a ?ltima em julho de 2017, quando o sistema estava com 31 meses de implanta??o. As unidades experimentais dos tratamentos em cons?rcio possu?am 36 x 18 m, totalizando uma ?rea de 648 m2, composta por quatro faixas de fileiras simples de eucalipto espa?adas a cada 12 m, intercaladas ? esp?cie forrageira (SSP). As fileiras laterais de eucalipto foram utilizadas como bordadura. Para as parcelas em monocultivo do capimmarandu as dimens?es foram de 36 x 10 m, totalizando uma ?rea de 360 m2. As vari?veis avaliadas foram: altura, DAP e volume m3ha-1 de madeira das ?rvores de eucalipto; RFA incidente sob o capim-marandu; pigmentos fotossint?ticos, temperatura foliar, altura, massa de forragem, produ??o de mat?ria seca, densidade populacional de perfilhos, rela??o l?mina foliar/colmo, rela??o material fresco/material senescente, n?mero de plantas m-2, mat?ria seca, mat?ria org?nica, prote?na bruta, FDN, FDA, P e K das plantas de capim-marandu. Os espa?amentos de 12 x 2 e 12 x 3 m de cultivo do eucalipto implicam em redu??o da quantidade RFA incidente sobre o sub-bosque, assim como redu??o da produtividade da forragem, contudo, a composi??o qu?mico-bromatol?gica do capim-marandu cultivado em SSP atende os par?metros para obten??o de pasto de qualidade. Houve redu??o do teor de FDN e FDA, e aumento do teor de prote?na bruta e minerais. At? os 31 meses de plantio, as ?rvores de eucalipto cultivadas nos dois espa?amentos pouco diferiram quanto altura e DAP, por?m se o objetivo ? facultar o crescimento do capim-marandu, recomenda-se o espa?amento 12 x 3 m, que propicia maior incid?ncia da RFA. As altera??es nas concentra??es das vari?veis analisadas sugerem adapta??es ao sombreamento o que comprova o capim-marandu fact?vel de ser utilizado em SSP nas condi??es ecol?gicas da regi?o de Curvelo-MG.Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2018.The present study aims to quantify the growth of eucalyptus trees (E. urophylla x E. grandis hybrid) and photosynthetically active radiation (PAR) incident on Silvipastoral System (SPS), verifying the effect of shading on grass plants -marandu (Brachiaria brizantha cv Marandu). The experimental area is located in the municipality of Curvelo-MG, the agrosilvipastoral system was implanted in a degraded pasture site, initially composed of three species - arboreal (eucalyptus), agricultural (corn) and forage (marandu grass), all planted at the same time. The marandu grass was evaluated in a randomized block design in a 2 x 4 + 1 factorial scheme, totaling nine treatments with four replicates (blocks). The factor A - two spacings of the eucalyptus cultivar - 12 x 2 and 12 x 3 meters, and factor B - four distances of the foragers in relation to the trees - 1, 2, 4 and 6 meters. After harvesting the corn, the system became silvipastoral. Before the four collections, a cut of uniformity of the forage was made, remaining the area in rest period of about 60 days. The first evaluation and cut occurred in january 2016 and the last in jJuly 2017, when the system was 31 months old. The experimental units of the consortium treatments had 36 x 18 m, totaling an area of 648 m2, composed of four bands of single eucalyptus rows spaced every 12 m, interspersed with the forage species (SPS). The lateral rows of eucalyptus were used as border. For the monoculture plots of marandu grass, the dimensions were 36 x 10 m, totaling an area of 360 m2. The variables evaluated were: height, DBH and volume m3ha-1 of wood from eucalyptus trees; PAR incident under the marandu grass; dry matter yield, dry matter yield, tiller population density, leaf / stem ratio, fresh material / senescent ratio, number of plants m-2, dry matter, organic matter, crude protein , NDF, ADF, P and K of the marandu grass plants. The spacings of 12 x 2 and 12 x 3 m of eucalyptus cultivation imply a reduction in the amount of PAR incident on the understorey, as well as reduction of forage yield, however, the chemicalbromatological composition of the Marandu grass grown in SPS meets the parameters for obtaining quality grazing. There was a reduction in NDF and ADF content, and an increase in crude protein and mineral content. Until 31 months of planting, the eucalyptus trees grown in the two spacings had little difference in height and DBH, but if the goal is to provide growth of marandu grass, it is recommended to spacing 12 x 3 m, which provides a higher incidence of PAR. The changes in the concentrations of the analyzed variables suggest adaptations to the shading, which proves the marandu grasses that can be used in SPS in the ecological conditions of the Curvelo-MG region

Growth and Nutrition of Eucalypt Rooted Cuttings Promoted by Ectomycorrhizal Fungi in Commercial Nurseries

ABSTRACT Ectomycorrhizal fungi (EMF) may improve the adaptation of eucalypts saplings to field conditions and allow more efficient fertilizer use. The effectiveness of EMF inoculum application in promoting fungal colonization, plant growth, nutrient uptake, and the quality of rooted cuttings was evaluated forEucalyptus urophylla under commercial nursery conditions. For inoculated treatments, fertilization of the sapling substrate was reduced by 50 %. The experiment was carried out in a completely randomized design in a 4 × 4 factorial arrangement, wherein the factors were inoculum application rates of 0 (control), 5, 10, and 15 gel beads of calcium alginate containing the vegetative mycelium of Amanita muscaria, Elaphomyces antracinus, Pisolithus microcarpus, andScleroderma areolatum, plus a non-inoculated treatment without fertilization reduction in the substrate (commercial). Ectomycorrhizal fungi increased plant growth and fungal colonization as well as N and K uptake evenly. The best plant growth and fungal colonization were observed for the highest application rate. The greatest growth and fungal colonization and contents of P, N, and K were observed at the 10-bead rate. Plant inoculation with Amanita muscaria, Elaphomyces anthracinus, and Scleroderma areolatum increased P concentrations and contents in a differential manner. The Dickson Quality Index was not affected by the type of fungi or by inoculum application rates. Eucalypt rooted cuttings inoculated with ectomycorrhizal fungi and under half the amount of commercial fertilization had P, N, and K concentrations and contents greater than or equal to those of commercial plants and have high enough quality to be transplanted after 90 days

ACCUMULATION POTENTIAL AND NUTRIENT CYCLING OF APPLE OF PERU (Nicandra physalodes)

Weed residues can influence nutrient cycling in agroecosystems. Quantifying this potential nutrient source may influence weed control and fertilisation practices. Nicandra physalodes (L.) Gaertn. is a weed with a short life cycle and a great ability to accumulate dry matter. Field observations suggest that N. physaloides residues are easily decomposed in soil. The objective of this study was to evaluate the effect of increasing of N, P and K doses on the growth of N. physalodes, as well as the nutrient content, chemical characteristics and C/N ratio of the weed. A randomised block design, arranged in split-plot with three replications, was utilised. The main plots were given four doses of NPK (Dose 1 - 0, 0.3 and 17.2 mg dm-3; Dose 2 - 30, 450.3 and 75.4 mg dm-3; Dose 3 - 60, 900.3 and 133.4 mg dm-3; and Dose 4 - 120, 1800.3 and 249.68 mg dm-3), and the subplots were harvested at ten time points after emergence (26, 33, 40, 47, 54, 61, 76, 91, 106 and 121 days). Higher dry matter production and N, P and K content were observed in plants grown on higher levels of fertiliser. The increase of N, P and K levels in the soil resulted in greater total accumulation of these macronutrients. The highest macronutrient contents were K and N. The treatments did not affect neutral detergent fibre (NDF), acid detergent fibre (ADF) and C/N ratio of plant. N. physalodes had low C/N ratio, low NDF and ADF levels, and great nutrient accumulation, suggesting that this plant is quickly decomposed, providing a rapid cycling of nutrients

Nicandra physalodes growth at different concentrations of N, P and K

A Nicandra physalodes (L.) Gaertn. é uma planta daninha que infesta com frequência áreas agrícolas brasileiras. O conhecimento do comportamento das plantas frente aos fatores de competição, como a disponibilidade de nutrientes no solo, é fundamental para direcionar o manejo dos agroecossistemas. Nesse contexto, objetivou-se avaliar o efeito de doses de N, P e K no crescimento de N. physalodes. O experimento foi conduzido em casa de vegetação, em delineamento de blocos casualizados arranjado em parcelas subdivididas, com três repetições. Nas parcelas foram aplicadas as doses de N, P e K: 0, 0,3 e 17,2 (D1); 30, 450,3 e 75,4 (D2); 60, 900,3 e 133,4 (D3); 120, 1800,3 e 249,68 mg dm-3 (D4) e nas subparcelas as épocas de colheita (26, 33, 40, 47, 54, 61, 76, 91, 106 e 121 dias após emergência (DAE)). Avaliou-se a matéria seca, área foliar, distribuição da matéria seca, taxa de crescimento relativo, altura e a eficiência fotoquímica do fotossistema II das plantas de N. physalodes. De maneira geral, as folhas apresentaram maior participação no acúmulo de matéria seca total até os 61 DAE; posteriormente, órgãos reprodutivos apresentaram maior participação. O aumento das doses de N, P e K proporcionou maior altura e produção de matéria seca da planta daninha, sendo que quando se dobrou as doses dos nutrientes aplicados observou-se aumento proporcional em acúmulo da matéria seca. Porém, ao ser cultivada nas condições de fertilidade natural do solo (tratamento D1), N. physalodes apresentou baixas taxas de crescimento. Conclui-se que o aumento das doses de N, P e K promove aumento do crescimento de N. physalodes, no entanto, o padrão de distribuição de biomassa não é alterado pela adubação. Essa espécie adapta-se bem a solos férteis, assim, pode-se considerar que a mesma tem maior potencial competitivo em solos de alta fertilidade.Nicandra physalodes (L.) Gaertn. is a weed that frequently infests Brazilian agricultural areas. Knowledge of the plant’s response to competition, in the form of nutrient availability in soil, is fundamental to management of agroecosystems. This study aimed to evaluate the effect of concentrations of N, P and K on the growth of N. physalodes. The experiment was carried out in greenhouse conditions, using a randomized complete block design with split-plot arrangement (4 x 10), with three replications. The main plots were four combinations of N, P and K: (L1) 0, 0.3 and 17.2 mg dm-3; (L2) 30, 450.3 and 75.4 mg dm-3; (L3) 60, 900.3 and 133.4 mg dm-3; and (L4) 120, 1800.3 and 249.68 mg dm-3. Subplots were used for 10 different harvest times: 26, 33, 40, 47, 54, 61, 76, 91, 106 and 121 days after emergence (DAE). The dry matter, dry matter partitioning, leaf area, relative growth rate, height and photochemical efficiency of photosystem II were measured in N. physalodes plants at each harvest time. Overall, the leaves showed higher total dry matter accumulation up to 61 DAE. After that, the reproductive organs showed higher accumulation. Increasing concentrations of N, P and K resulted in higher plant height and dry matter of N. physalodes. Moreover, doubling the nutrient levels resulted in a proportional increase in dry matter accumulation. However, N. physalodes showed lower growth under natural soil fertility conditions (L1 treatment). Thus, increasing concentrations of N, P, and K promoted higher growth of N. physalodes. Biomass distribution was not changed by fertilization. There is evidence that N. physalodes could adapt easily in fertile soil. Thus, this species has greater competitive potential in high fertility soils