R.G. Viana

Distribuição volumétrica e espectro de gotas de pontas de pulverização de baixa deriva

Objetivou-se neste trabalho avaliar a distribuicao volumetrica e o espectro de gotas das pontas de pulverizacao de baixa deriva TTI110015, AI110015 e AVI11001 sob diferentes condicoes operacionais. A distribuicao volumetrica foi determinada em bancada de ensaios padronizada analisando o coeficiente de variacao (CV%) de uma barra simulada em computador, utilizando pressoes de 200, 300 e 400 kPa, altura de 30, 40 e 50 cm em relacao a bancada e espacamento entre pontas de 40 a 100 cm. O espectro de gotas foi produzido utilizando-se apenas agua como calda em um analisador de particulas em meio aquoso, nas pressoes de 200, 300 e 400 kPa. Foram avaliados o DMV, a porcentagem de gotas com diâmetro inferior a 100 µm (%100 µm) e a amplitude relativa (AR). As pontas proporcionaram perfil descontinuo nas pressoes de 300 e 400 kPa e uniforme a 200 kPa. Na pressao de 200 kPa, as pontas foram adequadas apenas para aplicacao em faixa, e a 300 e 400 kPa, apenas para area total. Ocorreu menor CV (abaixo de 7%) com a maior pressao de trabalho e menor espacamento entre pontas. A medida que se aumentou a pressao de trabalho, reduziu-se o DMV. As pontas TTI110015 e AI110015 em todas as pressoes e a ponta AVI11001 na pressao de 200 kPa produziram gotas extremamente grossas e gotas grossas nas pressoes de 300 e 400 kPa apenas para a ponta AVI11001. As pontas proporcionaram baixos valores de amplitude relativa (AR) e gotas de tamanho uniforme, bem como produziram baixa porcentagem de gotas menores que 100 µm, principalmente TTI110015 e AI110015, com menor risco de deriva.

Potencial competitivo de biótipos de azevém (Lolium multiflorum)

The objective of this work was to evaluate the competitiveness of ryegrass biotypes resistant and susceptible to glyphosate, as well as their interference in wheat growth at different densities. At harvesting, 50 days after emergence, tillering, height, and leaf area of ryegrass plants were evaluated and shoot and roots of ryegrass and wheat were collected and their root, stalk and leaf dry mass was determined. Based on the data, the following variables were evaluated for ryegrass and wheat: crop growth rate (TCC = MSA/Ndays), with MSA being shoot dry mass and Ndays the number of days between emergence and plant harvesting; specific leaf area (SLA = Af /MSf),with Af being the leaf area and MSf leaf dry mass; and leaf area index (IAF = Af/St), St being soil area, indicating leaf area per soil area. Plant height, dry mass and leaf area of the susceptible ryegrass showed smaller reductions and better phenotypic plasticity, in function of the increasing density per soil area, compared to the resistant one. The susceptible biotype showed to be more competitive and its interference in wheat development was more visible at lower densities. It was concluded that the susceptible ryegrass biotype is more competitive than the resistant one.

Crescimento do eucalipto sob efeito da deriva de glyphosate

The possible negative effects of glyphosate drift on eucalyptus plants throughout their cycle are one of the many issues faced in forestry. Thus, 120 plants presenting variable degrees of intoxication were randomly selected at day 30 after application of 1.440 g ha-1 glyphosate, aiming to control the weeds in an area of Eucalyptus grandis x E. urophylla (urograndis hybrid) at 120 days after transplantation. The treatments were constituted by the following intervals: 0-5; 6-10; 11-20; 21-30; 31-40 and 41-50% of plant intoxication with 0-5% being considered the control treatment. Height and diameter were evaluated after plant selection, up to 360 days after application (DAA) and the intoxication symptoms were evaluated during this period. At 360 DAA wood volume (m3) was estimated and height and diameter gains were calculated. Plants with initial intoxication above 31% presented lesser height and diameter at 270 DAA Height gains were lesser in plants with initial intoxication above 41%. Lesser diameter was observed from 21% intoxication, with the plants with 41-50% intoxication displaying the lesser values for diameter growth. The damage caused by the drift affected wood production at 270 DAA, with the plants with 21-30, 31-40 and 41-50% intoxication being the ones presenting reduced wood volume of 18, 26 and 48%, respectively, in relation to the control treatment. The results confirmed the damage caused by glyphosate drift to eucalyptus plants. However, new evaluations should be performed to monitor the growth and development of the plants until the end of their cycle so as to elucidate the drift effects on the final production.

Misturas de herbicidas no manejo de plantas daninhas na cultura do feijão

Avaliou-se a eficacia da combinacao dos herbicidas fomesafen, fluazifop-p-butil e bentazon no manejo integrado de plantas daninhas do feijoeiro (plantio direto e convencional), cultivados em areas anteriormente com milho para grao e silagem. Foi avaliado tambem o residuo do fomesafen no solo aos 125 dias apos a aplicacao (DAA). No plantio convencional, Cyperus rotundus foi a especie dominante, enquanto no plantio direto a infestacao dessa especie foi muito baixa. Nenhuma das combinacoes de herbicidas foi eficiente no controle de C. rotundus. Com excecao de fluazifop-p-butil + bentazon (125 + 480 g ha-1), todas as combinacoes foram eficientes no controle das especies daninhas dicotiledoneas. Nao houve efeito dos tratamentos de herbicidas na produtividade do feijoeiro. O fomesafen, aplicado no plantio direto, causou toxicidade no feijao a partir da dose de 100 g ha-1, sobretudo no milho para silagem. No plantio convencional, sintomas mais leves somente foram observados na dose de 200 g ha-1. Houve residuo de fomesafen no solo apenas na area de plantio direto onde nao havia palhada sobre a superficie do solo, ou seja, na area anteriormente cultivada com milho para silagem. E possivel reduzir doses do fomesafen quando misturado ao bentazon sem afetar a produtividade do feijoeiro. Em areas de feijao cultivado apos colheita do milho para silagem e importante o uso de doses pequenas do fomesafen, para evitar toxicidade a culturas sensiveis subsequentes.

Exsudato radicular de imazapyr aplicado sobre mudas de diferentes clones de eucalipto

In the renewal of eucalypt crops, after tree harvesting, it is necessary to eliminate the sprouts that interfere with the initial development of the new stands. This elimination can be made by applying some herbicides on the shoots. One of the herbicides used is imazapyr, which, according to preliminary works carried out at the Universidade Federal de Vicosa, is capable to exsudate through the root system. In this case, questions arise concerning the exsudate ability to interfere in the development of the new plants; whether this capacity is the same for all eucalypt clones; at which imazapyr dose this problem is more serious; and the intensity at which the herbicide exsudate will interfere with the growth of the new stands. This work evaluated whether the root systems of different clones present different imazapyr exsudation intensities and the effect of the applied doses on herbicide concentration in the soil profile and its influence in subsequent crops. A dry mater decrease was verified in the sorghum plants when compared to the checks, in both 0-15 and 15-30 cm soil layers, evidencing imazapyr exsudation through the root system of the four clones analyzed. The toxic effect of the exsudates was observed in the entire soil volume reached by the eucalypt root system. Increased imazapyr doses increased the toxicity symptoms in sorghum imazapyr exsudation by all eucalypt clones was similar at the two depths analyzed.

Quantification and chemical composition of epicuticular wax of eucalyptus leaves

This work aimed to quantify and evaluate the chemical composition of the epicuticular wax from leaves of six Eucalyptus clones (UFV01, UFV02, UFV03, UFV04, UFV05 and UFV06). The epicuticular wax was extracted and quantified and their constituents analyzed by gas chromatography coupled with a mass spectrometer, with 31 constituents being identified in the six Eucalyptus clones appraised. The analysis of the samples revealed mostly the presence of hydrocarbons. The component found in larger proportion in the clones UFV02 (36.07%), UFV03 (33.00%) and UFV06 (40.98%) was 3β-acetoxy-urs-12-en-28-al, while in the clones UFV01 (17.80%), UFV04 (11.38%) and UFV05 (17.62%) the component found in larger proportion was hexacosane. The clones UFV02 and UFV04 presented the most variety of chemical components (19 components).This work aimed to quantify and evaluate the chemical composition of the epicuticular wax from leaves of six eucalyptus clones (UFV01, UFV02, UFV03, UFV04, UFV05 and UFV06). The epicuticular wax was extracted and quantified and their constituents analyzed by gas chromatography coupled with a mass spectrometer, with 31 constituents being identified in the six eucalyptus clones appraised. The analysis of the samples revealed mostly the presence of hydrocarbons. The component found in larger proportion in the clones UFV02 (36.07%), UFV03 (33.00%) and UFV06 (40.98%) was 3β-acetoxy-urs-12-en-28-al, while in the clones UFV01 (17.80%), UFV04 (11.38%) and UFV05 (17.62%) the component found in larger proportion was hexacosane. The clones UFV02 and UFV04 presented the most variety of chemical components (19 components).

Distribuição de líquido da ponta de pulverização com indução de ar e jato excêntrico AIUB 8502 sob diferentes condições

Objetivou-se com este trabalho avaliar a distribuicao de liquido da ponta de pulverizacao com inducao de ar e jato excentrico AIUB 8502 sob diferentes condicoes operacionais. Foram avaliados perfil individual, vazao, ângulo de abertura do jato, faixa de aplicacao e distribuicao volumetrica simulada de duas pontas AIUB 8502 nas pressoes de trabalho de 200, 300, 400 e 500 kPa, altura de 30, 40 e 50 cm em relacao ao alvo e espacamento entre pontas de 30 a 100 cm. Todas as analises foram realizadas seguindo a norma ISSO 5682-1, com algumas adaptacoes. A ponta apresentou distribuicao de liquido excentrica com um lado descontinuo e extremidade oposta excentrica, com queda abrupta do volume de liquido. A medida que se aumentou a altura da barra e a pressao de trabalho, alongou-se o perfil do jato. O maior numero de configuracoes uniformes foi obtido na altura de 50 cm, decrescendo nas alturas de 40 e 30 cm. A vazao e o ângulo do jato excentrico aumentaram com o incremento na pressao, nao havendo diferenca entre o ângulo do jato descontinuo e o total entre as pressoes de 400 e 500 kPa e de 200 e 300 kPa.