Miriam Hiroko Inoue

Calagem e o potencial de lixiviação de imazaquin em colunas de solo

Two greenhouse experiments were carried out from March to December 1999, to evaluate the leaching potential of imazaquin in soil columns, after applying different levels of liming in samples of Red Latosol Dystrophyc (LV) and Dusky Red Latosol (LR). The experiments consisted basically in spraying imazaquin (150 g ha-1) on the top of columns filled with soils with different levels of liming, what caused them to be at different final pH values. After spraying, a simulated rainfall of 30 mm (LV) or 90 mm (LR) was applied to the top of the columns. Three days later, cucumber (LV), lentil and sorghum (LR) seeds were distributed in a central furrow along the columns, and bioassays were performed to detect imazaquin leaching. The results showed that increasing liming levels resulted in a significantly higher leaching potential of imazaquin in soil columns. Sorghum was more sensitive than lentil as a bioindicator of imazaquin activity.

Agroclimatic aptitude of oil seed plant in the region of Tangará da Serra, Mato Grosso state, Brazil

Resumo - O objetivo do presente trabalho foi determinar a aptidao agroclimatica da cultura do pinhao manso (Jatropha curcas) na regiao de Tangara da Serra. Utilizaram-se historicos de dados diarios de precipitacao e temperatura do ar, disponibilizados pelo Instituto Nacional de Meteorologia (INMET) e Agencia Nacional de Aguas (ANA), analisando-os conforme as exigencias climaticas da cultura. A regiao em estudo demonstrou caracteristicas favoraveis ao desenvolvimento do pinhao manso, com precipitacao media anual variando de 1.260,1 mm a 1.815,5 mm e temperatura media entre 24,4 °C e 26,1 °C. A temperatura media mensal encontra-se nos niveis ideais da cultura, mas o regime pluviometrico mensal indica periodos longos de baixos niveis de precipitacao, principalmente durante os meses de junho, julho e agosto, com media inferior a 30 mm. De modo geral a regiao em estudo e classificada com aptidao plena para o cultivo do pinhao manso, no entanto, a utilizacao de tecnologias de irrigacao pode maximizar a produtividade, uma vez que o regime hidrico e um elemento climatico limitante em alguns periodos do ano. Palavras-chave - Jatropha curcas. Aptidao agricola. Clima.

Sistemas de manejo de plantas daninhas no desenvolvimento e na produtividade da soja

The choice of the adequate moment for the desiccation of the green cover that precedes the sowing is fundamental for the success of no-till soybeans. This context, the work was aimed to study two burndown systems: desiccation immediately before sowing (AP) and anticipated desiccation (MA), composed by two burndown herbicide applications. For MA, the first application of glyphosate (1240 g ha-1) occurred between 30 and 35 days before the sowing of the crop, and the second was done just before sowing. For AP, the applications (1080 to 1260 g ha-1 of glyphosate) occurred within 48 hours prior to sowing. The trials were developed in 2003/2004 growing season, in six localities in Parana State: Sertaozinho, Campo Mourao, Iretama, Pitanga, Boa Esperanca, and Mambore, in areas with high density of weeds preceding no-till soybean sowing. Evaluations related to weed control and soybean development and grain yield were performed. MA burndown systems provided improved control of weeds after crop emergence. Soybean plants from AP areas were shorter, in comparison to ME, evidencing a delay in the shoot growth. Reduction of grain yield was verified for all localities when AP burndown system was adopted, with reductions between 15% and 50%.

Lixiviação e degradação de diuron em dois solos de textura contrastante

This research was aimed at studying the leaching of diuron in soil columns, as well as the effect of different methods of reduction of microbial activity on diuron degradation in samples of a sandy loam soil (LVd) and a clay soil (LRd). To measure the downward movement of diuron (0; 1.6 and 3.2 kg ha-1), water layers of 0, 20 40, 60 and 80 mm were applied. For degradation studies, the methods used to restrict were as follow: sterilized in autoclave, methyl bromide application, amoxicillin, captan and amoxicilin+captan; soil samples were kept with or without light incidence. Water depths > 60 mm were enough to promote observable leaching in LVd samples. For clay soil, regardless of the water layer applied, herbicide movement was limited to the superficial soil layer. In degradation studies, biomass accumulation of bioindicator Brachiaria decumbens was higher in LRd samples with no restriction. LVd soil samples treated with any microbial activity restriction methods and exposed to light led to bioindicator biomass reduction, in comparison to others treatments. For both soils, biomass of B. decumbens was increased in soil samples that remained exposed to light.

Levantamento fitossociológico em pastagens degradadas sob condições de várzea

An assessment was carried out of two contingently flooded low land areas, located at the Experimental Farm of Leopoldina, owned by Empresa de Pesquisa Agropecuaria de Minas Gerais (EPAMIG)-Brazil-MG. Area 1 (3 ha) was cultivated with Angola-grass (Brachiaria mutica) pasture, not well managed and without any weed control for more than 10 years. Area 2 (5 ha) was occupied by Setaria grass (Setaria anceps cv. Kazungula) pasture which had been established in the previous rainy season, with forage being affected by the slow growth of the plants. For the phyto-sociological study, the inventory square method was applied through a square of 1,0 m2, randomly placed 19 times in area 1 and 41 times in area 2. The species found were identified and recorded. In the Angola-grass pasture, 27 species were identified, distributed in 11 families; in the Setaria grass pasture, 34 species were identified, distributed in 13 families. The most representative families in number of species were: Poaceae (11); Asteraceae (6); Papilionoideae (5); Malvaceae and Euphorbiaceae (4). The most frequent species were: Cynodon dactylon, Sida rhombifolia, Cyperus esculentus, Mimosa pudica, Senna occidentalis, Setaria anceps cv. Kazungula and Paspalum urvillei. In general, both areas were infested with weeds, including toxic, spinescent and rather unpalatable plants, reducing the animal support capacity of the pastures and preventing adequate utilization of the areas by the cattle.

Potencial de lixiviação de herbicidas utilizados na cultura do algodão em colunas de solo

Herbicide use intensification implies in the need to determine the potential of these substances to reach groundwater. Thus, this study aimed to evaluate the influence of different irrigation depths on the leaching potential of four herbicides commonly used in preemergence cotton weed control, in samples of two soils from Campo Novo do Parecis-MT (RQ-sandy texture) and Tangara da Serra-MT (LV-clay texture). Thus, a bioassay technique in soil columns was adopted, in which water depths of 0, 20, 40, 60, 80 and 100 mm were simulated after application of alachlor (RQ 2.40; LV 3.36 kg ha-1), oxyfluorfen (RQ 0.48; LV 0.72 kg ha-1), prometryne (RQ 0.75; LV 1.50 kg ha-1) and S-metolachlor (RQ 1.20; LV 1.44 kg ha-1). For soil samples with sandy texture (RQ), water depths of 80 and 100 mm led to leaching down to layers of 10-15 cm for alachlor and 15-20 cm for S-metolachlor.Regardless of the irrigation depth applied in the RQ samples, oxyfluorfen did not exceed the depth of 5-10 cm and prometryne could be detected at the depth of 10-15 cm only at water depth of 100 mm. In columns filled with clay soil (LV), oxyfluorfen did not move beneath the surface layer, even under the highest water depths and prometryne reached the depth of 5-10 cm under 80 and 100 mm. The herbicides alachlor and S-metolachlor reached 10-15 cm depth under water depths of 80 and 100 mm in the LV. A more intense downward movement of the herbicide molecules was found in sandy soil samples (RQ) than in clay texture soil samples (LV).

Levantamento fitossociológico em pastagens

Objective of this study was to identify the weed community in areas of pasture. The phyto-sociological survey was conducted during November and December, 2009 in three regions: two located in Tangara da Serra-MT (region A = areas surrounding the town; and region B = areas in the Antonio Conselheiro Settlement and one area in Barra of the Bugres-MT (region C). Five properties were analyzed in each region, each containing 10 plots of 25 m2. The weed species were counted and identified in the plots. Data were analyzed by calculating density, frequency, abundance, relative density, relative frequency, relative abundance, importance value index (IVI), and similarity index. Thirty-eight weed species were identified, distributed among 18 families, with Asteraceae (7), Fabaceae (6), Arecaceae (3), Euforbiaceae (3) and Poaceae (3) being the most representative in number of species. The species most frequently found were: region A - Sida spp. (IVI: 127.93) and Eragrostis plana (IVI: 42.18); region B - Eragrostis plana (IVI: 54.78), Mimosa wedelliana (IVI: 52.39), and Sida spp. (IVI: 50.30); and region C - Sida spp. (IVI: 73.92), and Mimosa wedelliana (IVI: 26.55). A significant similarity was found between regions A and B (52.63%) and between regions B and C (50.98%).

Efeito residual de herbicidas aplicados em pré-emergência em diferentes solos

The objective of this work was to monitor the residual effect of the herbicides ametryne, clomazone and diuron, applied in pre-emergence, using Psament and Red Latosol with contrasting texture and composition. Thus, six experiments were conducted under greenhouse conditions with samples of Psament (sandy texture) and Red Latosol (clay texture). The residual effect of ametryne (0, 1.60 and 2.40 kg ha-1), clomazone (0, 0.90 and 1.10 kg ha-1) and diuron (0, 1.60 and 3.20 kg ha 1) was evaluated by sowing the test plant (Cucumis sativus or Brachiaria decumbens) at 0, 25, 50, 75 and 100 days after application (DAA). Ametryne was found to provide 80% control up to 40 DAA, independent of type of soil and dose. Clomazone showed satisfactory residual effect when applied at the dose recommended for clay soil, maintaining control over 80% up to 71 DAA. In sandy soil, the control was not satisfactory up to 25 DAA, even at doses recommended for clay soil. Diuron showed high stability in clay soil, observing control over 91% up to 100 DAA at the recommended dose and control over 80% up to 54 DAA at the dose recommended for sandy soil. However, in sandy soil, no residual effect increase was observed, even when the dose recommended for clay soil was applied.

Seletividade de herbicidas aplicados em pré-emergência na cultura do algodão

The cultivation of cotton has great economic and social importance as it is the most widely used fibre in the textile sector. It is however a crop that is highly sensitive tweeds, and there are few selective herbicides for the crop. With this in mind, this study aimed to evaluate the selectivity of herbicides applied to pre-emergent cotton crops. The herbicides, alachlor, S-metolachlor, diuron, prometryne, trifluralin and oxyfluorfen were applied both individually and in mixture to the variety FMT-701 in the towns of Diamantino and Campos de Julio, Mato Grosso. The experimental design used was of randomized blocks with 16 treatments and four replications. To evaluate selectivity, assessments were made for height at 36, 66 and 150 days after application (DAA), for phytotoxicity at 14, 21, 29 and 36 DAA, for growth at 21 and 49 DAA, for the number of bolls at 141 DAA and for cotton-seed yield at 193 DAA. The data were submitted to joint-analysis and the Scott-Knott cluster test (p>0.05). The results indicated that some treatments resulted in lower plant height in certain evaluations, and that a large part of the treatments caused injury in the initial stage of cultivation. It was found that the treatments did not produce significant differences for the characteristics of plant growth, number of bolls and cotton-seed yield, proving that all the treatments assessed may be used in weed management.

Emergence and Control of Rottboelia spp. in Different Months in Sugarcane Cultivation1

This study aimed to evaluate the control of Rottboelia spp. with the formulated mixture diuron + hexazinone + sulfometuron-methyl and the emergence of this weed in the months of April, May, June, July, August, September, October and November 2012 in sugarcane cultivation, cultivar RB867515. The experimental design consisted of randomized blocks, with treatments in a 4 x 4 factorial arrangement with four replicates for the months of April to November. The emergence tests used a randomized block design, in a 8 x 5 split plot arrangement with four replicates. The analyzed factors were the rates of the formulated mixture (diuron + hexazinone + sulfometuron-methyl), which consisted of: 1,809.00 + 510.00 + 43.50 g ha-1 (T2); 1,507.50 + 425.00 + 36.25 g ha-1 (T3) and 1,386.90 + 391.00 + 33.35 g ha-1 (T4), in addition to the control (T1) without application. Controls over 80.00% were found for the application performed in the month of November in evaluations at 30 and 60 DAA, regardless of the rate in use. All treatments were selective for the sugarcane cultivar RB867515. The tests conducted in the months of August, September, October and November showed the highest population density.