Edinalvo Rabaioli Camargo

Rice herbicide monitoring in two Brazilian rivers during the rice growing season

Irrigated rice production can involve environmental contamination with pesticides due to the proximity of the fields to rivers and to management problems. During three years (2000 to 2003) the rice herbicides clomazone, propanil and quinclorac were quantified in water during the rice growing season, in the Vacacai and Vacacai-Mirim Rivers, located in Rio Grande do Sul (RS) State, Brazil. Water samples were taken at several locations in each river, selected by their importance in terms of rice drainage area. The samples were analyzed by HPLC-UV. At least one herbicide was detected in 41% of the samples from the Vacacai River and 33% from the Vacacai-Mirim River. The most frequent herbicide in both rivers and in each year was clomazone. The amount of herbicides in the river water was dependent on the rainfall regime. River water contamination by rice herbicides is probably caused by the rice water management used in the fields. The maintenance of flooded areas makes herbicides prone to contaminate the environment. To reduce the environmental contamination risk it is necessary to adopt measures to avoid overflow of flooded rice fields, keeping paddy water in the field for time enough to reduce the herbicide concentration before its release and enhancing the quality of the levees to reduce the probability of paddy rice overflow.

Arroz tolerante a imidazolinonas: controle do arroz-vermelho, fluxo gênico e efeito residual do herbicida em culturas sucessoras não-tolerantes

After several decades searching for tools to control red rice, imidazolinone tolerant rice was developed to selectively control red rice. To better understand this technology An experiment was conducted in 2004/2005, in Santa Maria, Rio Grande do Sul, Brazil to evaluate: 1) red rice control by imidazolinone herbicides in Clearfield™ rice; 2) evaluate the imidazolinone herbicide carryover effect on rygrass and non-tolerant rice (IRGA 417) and 3) evaluate the outcrossing rates between Clearfield rice and red rice. The experimental design was a randomized block design, with 3 treatments and 12 replications. To determine the outcrossing rates between Clearfield rice and red rice, virtually all the red rice panicle was collected and analyzed in the area. The carryover effect was tested using ryegrass and a non-tolerant rice cultivar (IRGA 417). The herbicides tested controlled red rice. Although injury to Clearfield rice was observed, the herbicide did not affect yield. Herbicide carry-over to non-tolerant rice was observed, reducing plant stand on rice seeded 361 days after herbicide application. Natural out-crossing occurred between Clearfield rice and red rice, at rates of 0.065%.

Acetylcholinesterase enzyme activity in carp brain and muscle after acute exposure to diafuran

Exposicao a inseticidas em concentracoes elevadas no ambiente podem ocasionar efeitos adversos subletais em organismos aquaticos. Alevinos de carpa hungara (Cyprinus carpio, Linnaeus, 1758), carpa capim (Ctenopharyngodon idella, Valenciennes, 1844) e carpa cabeca grande (Aristichthys nobilis, Richardson, 1845) foram expostos ao diafuran, um inseticida utilizado na cultura do arroz no sul do Brasil. O objetivo deste estudo foi verificar a relacao entre concentracao letal mediana (CL50) do diafuran e a atividade da enzima acetilcolinesterase (AChE) em cerebro e musculo dessas especies, como um possivel biomarcador inicial da exposicao a este inseticida. A CL50 foi determinada com peixes expostos a concentracoes de diafuran em 96 h: carpa hungara: controle; 0,5; 1,0; 1,5; 2,0; 2,5 e 3,0 mg L-1; carpa capim: controle; 1,0; 2,0; 3,0 e 3,5 mg L-1 e carpa cabeca grande: controle; 0,5; 1,0; 1,5; 2,0; 3,0 e 4,0 mg L-1, bem como a determinacao da AChE em concentracoes proximas da CL50 para essas especies. Valores de CL50 (concentracoes nominais) foram de 1,81 mg L-1 para carpa hungara, 2,71 mg L-1 para carpa capim e 2,37 mg L-1 para carpa cabeca grande. Todas as carpas expostas ao diafuran estavam letargicas (menores concentracoes) ou imoveis. Diafuran inibiu significativamente a atividade da AChE em cerebro (~38 %) e musculo (~50 %) de todas as especies estudadas. Atividade da AChE em musculo para carpa cabeca grande foi mais alta que cerebro (14,44 contra 5,94 µmol min-1 g proteina-1, respectivamente). Este estudo demonstrou que concentracoes de diafuran utilizadas na cultura do arroz podem afetar o comportamento de Cyprinus carpio, Ctenopharyngodon idella e Aristichthys nobilis, e a atividade da acetilcolinesterase cerebral e muscular pode ser um biomarcador inicial de toxicidade deste inseticida.Exposicao a inseticidas em concentracoes elevadas no ambiente podem ocasionar efeitos adversos subletais em organismos aquaticos. Alevinos de carpa hungara (Cyprinus carpio, Linnaeus, 1758), carpa capim (Ctenopharyngodon idella, Valenciennes, 1844) e carpa cabeca grande (Aristichthys nobilis, Richardson, 1845) foram expostos ao diafuran, um inseticida utilizado na cultura do arroz no sul do Brasil. O objetivo deste estudo foi verificar a relacao entre concentracao letal mediana (CL50) do diafuran e a atividade da enzima acetilcolinesterase (AChE) em cerebro e musculo dessas especies, como um possivel biomarcador inicial da exposicao a este inseticida. A CL50 foi determinada com peixes expostos a concentracoes de diafuran em 96 h: carpa hungara: controle; 0,5; 1,0; 1,5; 2,0; 2,5 e 3,0 mg L-1; carpa capim: controle; 1,0; 2,0; 3,0 e 3,5 mg L-1 e carpa cabeca grande: controle; 0,5; 1,0; 1,5; 2,0; 3,0 e 4,0 mg L-1, bem como a determinacao da AChE em concentracoes proximas da CL50 para essas especies. Valores de CL50 (concentracoes nominais) foram de 1,81 mg L-1 para carpa hungara, 2,71 mg L-1 para carpa capim e 2,37 mg L-1 para carpa cabeca grande. Todas as carpas expostas ao diafuran estavam letargicas (menores concentracoes) ou imoveis. Diafuran inibiu significativamente a atividade da AChE em cerebro (~38 %) e musculo (~50 %) de todas as especies estudadas. Atividade da AChE em musculo para carpa cabeca grande foi mais alta que cerebro (14,44 contra 5,94 µmol min-1 g proteina-1, respectivamente). Este estudo demonstrou que concentracoes de diafuran utilizadas na cultura do arroz podem afetar o comportamento de Cyprinus carpio, Ctenopharyngodon idella e Aristichthys nobilis, e a atividade da acetilcolinesterase cerebral e muscular pode ser um biomarcador inicial de toxicidade deste inseticida.

Análise de coeficiente de trilha para os componentes de produção em arroz

Eighty eight rice genotypes were evaluated during four years aiming to study the relationship among yield components. In each year, the experimental design was a completely randomized block design with four replications and the variables studied were: plant height, seed yield, spikelet sterility, number of seeds per panicle, 1000 seeds weight and head grains. The estimation of correlations and the path coefficient analysis were conducted with the GENES software. The genotypes showed significant variability for all the variables analyzed within each one of years. It was concluded that variable selection must be carried out among the cultivars that are more similar and using a greater number of variables allows better inferences about rice yield components. Grain weight was the yield of component that most affected seed yield rice plants.

Qualidade da água no consórcio de peixes com arroz irrigado

The goal of the present work was to evaluate quality parameters of the water utilized in combination of the fish culture with irrigate rice. The experiment was carried in low land area, with rice pre-germinate system associated with farming of carps and silver catfish, where the levels of dissolved oxygen, temperature, pH, hardness, total alkalinity, ammonia, nitrite and water transparency were weekly monitored. The physical-chemical characteristics of the water (temperature, pH, hardness, total alkalinity, ammonia, and nitrite) do not affect the growth and development of the fish in combination with irrigate rice for cultived species (60% commom carp, 20% grass carp, 10% silver catfish, 5% silver carp and 5% bighead carp) Although, the quantities of fish utilized and time of entry fingerlings affect certain water quality parameters (dissolved oxygen and water transparency) in general they maintain in levels adequate to with the standard for these species.

Produção de novilhos de corte com suplementação em pastagem de azevém submetida a doses de nitrogênio

O experimento foi realizado em varzea sistematizada com o objetivo de comparar os efeitos do uso de doses de N em cobertura, associadas a niveis de suplementacao energetica, sobre o desempenho animal e a qualidade e producao de forragem. Os tratamentos foram: 300N+0,8S = adubacao com 300 kg de N/ha + suplementacao com grao de milho moido (0,8% do PV/dia); 200N+0,4S = adubacao com 200 kg de N/ha + suplementacao com grao de milho moido (0,4% do PV/dia); e 100N = adubacao com 100 kg de N/ha, sem suplementacao. Foram utilizados novilhos de corte da raca Charoles e suas cruzas com Nelore com idade inicial de 8 a 10 meses. A pastagem foi manejada sob lotacao continua e carga variavel, no periodo de 15/07 a 03/11/2000, totalizando 110 dias de utilizacao. O teor de PB, a digestibilidade in vitro da MO (DIVMO) e a oferta de forragem (OF) foram maiores no inicio do periodo de pastejo e apenas a OF diferiu entre os tratamentos. As doses de N em cobertura, associadas a niveis de suplementacao energetica em pastagem de azevem, nao alteraram o ganho medio diario dos animais, mas resultaram em maior carga animal e maior ganho de peso vivo por hectare.

Manejo da irrigação em cultivares de arroz no sistema pré-germinado

In the pre-germinate system, the rice field is flooded before sowing and about three days later, the initial drainage takeplace in order to promote the plants initial growth but there occurs loss of nutrients and water. Then, three irrigation managements have been evaluated: water removal three days after sowing, water removal 30 days after sowing and without water removal, associating three rice cultivars with the objective to measuring rice grains yield, and loos nutrients with water removal. The water managements evaluated have not influenced the rice plant parameters. The grains yield varied according to the year, with an average 5,100, 9,565 and 7,078kg ha-1 ha in the years 2002/03, 2003/04 and 2004/05, respectively. Only in 2003/04, the grains yield was different among the rice cultivars. In 2002/03 and 2003/04, the phosphorous nutrient was similar among treatments, but in 2004/05 a great loss occurred when water removed three days after sowing. Concerning potassium, the highest concentrations were observed in water when it was removed three days after sowing. Results demonstrate that a continuous water sheet should be kept to preserve the nutrients within the field since it does not affect the crop yield and reduce the environmental impact of the water bodies.

População de plantas, dose de nitrogênio e aplicação de fungicida na produção de arroz irrigado: I-características agronômicas

A field experiment was aimed at evaluating the effects of plant densities, nitrogen rates and chemical disease control on agronomic characteristics that affect grain yield of irrigated rice. The study was conducted during 2003/2004, in the Departamento de Fitotecnia of Universidade Federal de Santa Maria. The experiment was arranged in randomized blocks with sub-plots and four replicates, in Santa Maria-RS, Brazil and the treatments were: three plant densities (150, 260 and 380plants m-2), five nitrogen rates (0, 40, 80, 120 and 160kg ha-1) with and without chemical foliar disease control. The nitrogen was dressing was twice split at initial tillering and panicle differentiation. Grain yield increased in a quadratic fashion in response to nitrogen rates to up to 97kg ha-1. The use of fungicides to control foliar diseases resulted in higher grain yelds regardless of plant population or nitrogen fertilizer rates. Irrigated rice can compensate yield components between 150 and 380plants m-2. The most efficient rate of nitrogen was 97kg ha-1. Chemical foliar diseases control increases irrigated rice productivity even at low disease incidence.

Desempenho de genótipos de arroz irrigado cultivados no sistema pré-germinado com inundação contínua

No sistema pre-germinado de cultivo do arroz irrigado, adota-se o manejo de retirada da agua da lavoura, aproximadamente aos tres dias apos a semeadura, objetivando melhor estabelecimento das plântulas. No entanto, esta pratica acarreta perda de agua e nutrientes, alem da reinfestacao com plantas daninhas. A permanencia da lâmina de agua na lavoura, durante todo o ciclo da cultura, seria uma proposta de manejo capaz de minimizar estes problemas. Sendo assim, objetivou-se avaliar o desempenho de genotipos de arroz irrigado, quando submetidos ao cultivo em lâmina continua, especialmente quanto ao acamamento de plantas, aspecto considerado limitante neste manejo de irrigacao. Para tal, nos anos agricolas de 2000/01 a 2002/03, foram conduzidos experimentos em area de varzea sistematizada, em solo classificado como Planossolo Hidromorfico eutrofico arenico. Os tratamentos foram compostos por 8, 12 e 15 genotipos no primeiro, segundo e terceiro ano, respectivamente. No ano 1, a produtividade media foi de 7279kg ha-1, sendo o genotipo IRGA 1572-11-1F-1-4-4 (8297kg ha-1) o mais produtivo em valores absolutos. A porcentagem de acamamento variou entre 0 e 60% e a maioria dos tratamentos situou-se entre 0-20%. Todos os genotipos exibiram acamamento de plantas, exceto El Paso L 144. No ano 2, a produtividade media foi de 8492kg ha-1 e o genotipo BRS-Pelota o mais produtivo (9282kg ha-1), nao tendo sido verificado acamamento em nenhum dos genotipos. No ano 3, a produtividade media foi de 6202kg ha-1 e esteve relacionada a elevada porcentagem de plantas acamadas decorrente de intemperies climaticas, ocorridas na fase de maturacao. Constatou-se que a produtividade dos genotipos pode ser elevada neste manejo de irrigacao, mas o acamamento de plantas limita o potencial produtivo, dependendo das condicoes ambientais e do genotipo utilizado.

Manutenção da área foliar e produtividade de arroz irrigado com a aplicação de fertilizantes foliares no estádio de emborrachamento

The use of foliar fertilizers applied to the reproductive phase of rice can improve the plant nutrition and protect the field against foliar diseases with gains in yield. The objective of this experiment was to evaluate the use of the foliar fertilizers applied to the booting stage in order to verify the irrigated rice yield. The experiment was carried out in 2005/06 in a lowland area in Santa Maria-RS, Brazil. The treatments, arranged in a randomized block design with four replications, were constituted by 10 foliar fertilizers available in the market, two products applied to seeds, a fungicide, and a check treatment. The treatments presented no effects on any of the variables studied. The suitable climatic conditions and the fertilizer management carried out before the application of the foliar treatments led to the achievement of about 10,000 kg ha-1 yield, showing that there was no limitation on the level of yield obtained. The products utilized in this study did not increase the irrigated rice yield.