This study evaluated the influence of seasonality in essential oil (EO) chemical composition of Mentha x piperita L. and Mentha viridis L. grown in southeast of Brazil. Leaves were collected from November 2011 until August 2013, in the middle of the following seasons: Spring (November), Summer (February), Autumn (May) and Winter (August). EO extraction was carried out by hydrodistillation in Clevenger apparatus for 1 hour. Chemical composition of EO was analyzed by GC-FID and GC-MS. The EO content and its chemical composition were influenced by seasonality in both species. The highest EO content was obtained for M. x piperita during spring (4.26%) and for M. viridis during spring (3.30%) and summer (3.70%). Mentha x piperita increased menthol (16.31 to 41.26%), neomenthol (3.02 to 6.39%) and menthone (5.56 to 41.58%) contents during spring and summer, respectively. Whereas, M. viridis EO content did not show a quality response pattern in relation to seasonality. Therefore, harvest time for M. x piperita is recommended during spring, and for M. viridis is recommended during spring and summer.

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Fertilization of the soil with organic fertilizers has been gaining importance within the concept of sustainable crop production. This study aimed evaluates the effects of dosages of cattle and poultry manure on Achillea millefolium L. as regards the vegetative growth and the content and chemical composition of its essential oil. For the cattle manure fertilization the dosages evaluated were: 1) soil with no fertilizer; 2) soil + 3.0 kg m -2 ; 3) soil + 6.0 kg m -2 ; 4) soil + 9.0 kg m -2 and 5) soil + 12.0 kg m -2 . For fertilization with poultry manure: 1) soil without fertilizer; 2) soil + 1.5 kg m -2 ; 3) soil + 3.0 kg m -2 ; 4) soil + 4.5 kg m -2 and 5) soil + 6.0 kg m -2 . The experimental design was completely randomized, with four replications per treatment and four plants per experimental plot. Harvesting took place at 110 days and the following variables were measured: shoot and root dry biomass; root to shoot ratio and the content, yield and chemical composition of the essential oil. Data were submitted to variance and regression analyses. A. millefolium has more intense response in fertilization with poultry manure than to that of cattle, where the dosage of 6 kg m -2 presented the greatest shoot dry weight and highest yield of essential oil. Without regard to fertilization, the essential oil of A. millefolium consists mainly of chamazulene, with the applied treatments not significantly interfering in the oil chemical composition and content.RESUMO -A fertilização dos solos com adubos orgânicos tem adquirido importância do ponto de vista da concepção de produção vegetal sustentável. Foi objetivo deste trabalho avaliar os efeitos de dosagens de esterco bovino e avícola em Achillea millefolium L. no crescimento vegetativo, teor e composição química do óleo essencial. Na fertilização com o esterco bovino avaliaram-se as doses: 1) Solo sem adubação; 2) solo + 3,0 kg m -2 ; 3) solo + 6,0 kg m -2 ; 4) solo + 9,0 kg m -2 ; 5) solo + 12,0 kg m -2 . Na adubação com esterco avícola: 1) solo sem adubação; 2) solo + 1,5 kg m -2 ; 3) solo + 3,0 kg m -2 ; 4) solo + 4,5 kg m -2 e 5) solo + 6,0 kg m -2 . O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições por tratamento e quatro plantas por parcela experimental. A colheita ocorreu aos 110 dias e avaliaram-se as biomassas secas da parte aérea e raiz, razão raiz/parte aérea, teor, rendimento e composição química do óleo essencial. Os dados foram submetidos à análise de variância e de regressão. A. millefolium responde com maior intensidade a adubação com esterco avícola que com a bovina, onde a dose de 6 kg m -2 apresentou o maior acúmulo de biomassa seca da parte aérea e maior rendimento de óleo essencial. Independente da adubação das plantas, o óleo essencial da A. millefolium é constituído majoritariamente por camazuleno e os tratamentos aplicados não interferiram expressivamente na composição e teor dos constituintes químicos do óleo.Palavras-chave: Achillea millefollium L.. Óleos essenciais. Fertilizante orgânicos. Fertilidad...

RESUMO -Considerando que há relatos de possível intoxicação de milho por causa da dessecação de capim braquiária, o objetivo deste estudo foi determinar o melhor período para semear o milho 'Yield Gard DKB 390 YC' após a dessecação da cobertura. O delineamento experimental foi inteiramente casualizado, com quatro repetições.Os tratamentos consistiram em seis períodos de dessecação do capim ruziziensis (25, 20, 15, 10, 05 e 0 dias antes da semeadura do milho) e uma testemunha sem cobertura. As dessecações foram feitas em pleno florescimento do capim ruziziensis com glyphosate a 1,44 kg ha -1 . Foram avaliadas as plantas de milho aos 30 e 50 dias após a semeadura (DAS) quanto à altura, área foliar, massa seca de folhas e caule. Aos 150 DAS, foi avaliada a altura de plantas e a inserção da espiga, diâmetro e comprimento da espiga, massa de 100 grãos e produtividade de grãos. A dessecação do capim ruziziensis no mesmo dia da semeadura do milho reduziu a altura das plantas, a altura de inserção da espiga, o diâmetro da espiga e a produtividade de grãos. A melhor época para a semeadura do milho 'Yield Gard DKB 390 YC' após a dessecação de capim ruziziensis com glyphosate foi aos 25 dias após a dessecação. Palavras-chaves:Brachiaria ruziziensis, Urochloa ruziziensis, cobertura vegetal, plantio direto, glyphosate.ABSTRACT -Considering the possible occurrence of maize intoxication due to the desiccation of ruziziensis grass, the objective of this study was to evaluate the best period for sowing 'Yield Gard DKB 390 YC' in the no-tillage system.The experimental design was completely randomized with four replications. The treatments consisted of six periods of desiccation of ruziziensis grass (25, 20, 15, 10, 05 and 0 days before sowing maize) and one control without cover.The desiccations were done at full bloom of the ruziziensis grass with glyphosate at 1.44 kg ha -1 . The maize plants were evaluated at 30 and 50 days after sowing (DAS) for height, leaf area, leaf and stem dry biomass. At 150 DAS, plant height and cob insertion, cob diameter and length, 100 grain mass and yield were evaluated. The desiccation of ruziziensis grass in the same day of maize sowing caused reduction in plant height, cob insertion height, cob diameter and yield. The best time for sowing 'Yield Gard DKB 390 YC' was 25 days after desiccation of ruziziensis grass with glyphosate.

Weeds play a strong pressure on the eucalyptus early growth, leading to a delay in their development. Therefore, many studies have tried to identify eucalyptus clones that are more tolerant to weed competition to supply information to producers, genetic improvement programs and the scientific community. The objective of this study was evaluate the interference of signal grass (Urochloa decumbens) and guinea grass (Panicum maximum) in the early growth of six clones of Eucalyptus urograndis, as well as the reciprocal effect. The experiment was conducted in an open and semi-controlled area in 8-L pots using a completely randomized experimental design with a 3 x 6 factorial scheme (U. decumbens, P. maximum and weed-free control and six eucalyptus clones). After ninety days of planting, the following variables were measured: eucalyptus stem diameter, height, total chlorophyll concentration, chlorophyll fluorescence (Fv/Fm), net assimilation rate and eucalyptus and weed dry biomass. In coexistence with Guinea grass (Panicum maximum), clone 3 (ms 709 H) exhibited a 78.2% reduction in dry biomass compared to clone 4 (C 219 H), which obtained the highest dry biomass. In coexistence with signal grass (Urochloa decumbens), clone 6 (ms 686 H) was the most negatively affected by weed competition, with an 80.7% lower dry biomass than clone 4. In general, clones 1 (ms 710 H), 2 (H 1069) and 4 were more resistant, and clones 3 and 6 were more sensitive to weed interference. Both weeds were affected by eucalyptus, but Guinea grass was more sensitive than signal grass.

The repetitive use of herbicides with the same mechanism of action causes the selection of resistant weeds, such as ryegrass. Considering the occurrence of ryegrass (Lolium multiflorum) in eucalyptus, a crop on which glyphosate is used, it is necessary to study its interference. The objective of this study was to evaluate the effect of densities (0, 10, 20, 30 and 50 plants m-2) of two ryegrass biotypes (resistant and susceptible to glyphosate) on seedlings of two eucalyptus clones (I-144 and 1407). The used experimental design was in randomized blocks with four replications, following a 2 x 5 factorial arrangement for each clone. The height and diameter of the clones were evaluated at 0, 14, 28, 42, 56 and 70 days after transplantation (DAT), and at 70 DAT, the leaf area and dry biomass of eucalyptus and ryegrass were also evaluated. There was no interaction between the biotype and densities factors for the clones, but all characteristics were affected by the factors separately. The increase in ryegrass densities affected all the characteristics evaluated in the clones, being the leaf area of the eucalyptus clones the most affected one, with reductions of up to 72%. The resistant biotype was less competitive, causing reductions in clones of up to 39% in leaf area, 5% in diameter and 1% in height, while the susceptible biotype resulted in reductions of 51%, 13% and 6%, respectively. Thus, the tolerable density by the culture to the resistant biotypes may be greater than that of the susceptible biotypes.

ABSTRACT: Stress caused by extreme temperatures is one of the main elements that limit the geographical distribution and the seasonal growth of several plants, causing a severe delay in their development, reducing the photosynthetic rate and signaling the synthesis of defense compounds. Considering the current environmental changes and the damages that these changes can cause in plant physiology and growth, the objective of this work was to understand the interactions between temperature, physiology and growth, and to characterize the impact of temperature changes on the initial development of Vernonia ferruginea Less. Seedlings of this species were conditioned in germination chambers at previously adjusted constant temperatures (10, 20, 25, 30, and 35 oC) for sixty days, in order to evaluate physiological and growth parameters. The optimum temperature range for the initial growth of V. ferruginea is between 25 and 30 oC. The stress caused by sub-optimal and over-optimal temperatures affected cell homeostasis and caused a delay in the growth and development of seedlings. In stressful situations, growth inhibition and the activation of response mechanisms were observed for the adaptation and maintenance of cellular homeostasis through the accumulation of the proline osmoprotectant and soluble carbohydrates. Additionally, plants presented a normal development within a wide temperature range, despite the development delay, the change in gas exchanges and the synthesis of substances related to the defense system.

Câmpus de Jaboticabal -SP www.fcav.unesp.br/rab Revista Agronomia Brasileira │ Volume 2 │ rab201815 8/6/2018