Lisiane Camponogara Fontana

Habilidade competitiva relativa de milhã em convivência com arroz irrigado e soja

The objective of this work was to compare the relative competitive ability of crabgrass with flooded rice and soybean crops. Five experiments were performed in the 2009/2010 and 2010/2011 seasons, in a completely randomized design with four replicates. The treatments consisted of plant proportions of crabgrass, flooded rice or soybean (at 100:0, 75:25, 50:50, 25:75 and 0:100%). Leaf area and shoot dry weight were evaluated at 45 days after emergence. The competition between crabgrass and flooded rice or soybean occurs for the same environment resources. Crabgrass plants have a lower individual competitive ability than flooded rice and soybean, when they occur in the same proportion of plants. When flooded rice or soybean are associated with crabgrass, the intraspecific competition dominates, while for the weed the interspecific competition prevails as the most harmful.

Influência de doses reduzidas do glyphosate no tomateiro (Lycopersicon esculentum)

Tomato plant (Lycopersicon esculentum) is grown in all regions in Brazil since it is widely used in cooking, processed or fresh. Glyphosate drift has been found rcited as one of the factors interfering negatively in vegetables cultivated in areas adjacent to rice plantations. The objective of this study was to evaluate the effects of reduced rates of glyphosate on tomato plants, applied at of 0, 15, 30, 45, 60, 75 and 90% of the commercial dose (1.260 g ha-1) 30, 50 and 70 days after transplanting (DAT) the tomato plants. The variables analyzed were: phytotoxicity, plant height, number of flowering clusters, and flower and fruits/plant. The data were submitted to analysis of variance, the Tukey test and regression. Glyphosate application at rates higher than 378 g ha-1 affected the growth of the tomato plants negatively, regardless of their development stage.

Resposta de plantas de beterraba (Beta vulgaris) e de cenoura (Daucus carota) à deriva simulada de glyphosate e clomazone

Varias especies de hortalicas sao de muita importância para a alimentacao humana e tornam-se alvos da deriva de herbicidas, pois comumente sao cultivadas nas proximidades de culturas como arroz, soja e milho, pulverizadas com esses produtos. Neste trabalho, objetivou-se verificar possiveis efeitos de doses reduzidas dos herbicidas glyphosate e clomazone sobre plantas de beterraba (Beta vulgaris) e de cenoura (Daucus carota), em diferentes fases de desenvolvimento. As doses avaliadas dos herbicidas foram de 0, 5, 10, 15 e 20% da dose recomendada, equivalentes a 0, 63, 126, 189 e 252 g ha-1 de glyphosate e 0, 14,4, 28,8, 43,2 e 57,6 g ha-1 de clomazone, respectivamente, aplicadas aos 20, 30 e 40 dias apos a emergencia das culturas. Observou-se aumento no percentual de fitotoxicidade do glyphosate com o incremento na dose do herbicida, e a maior suscetibilidade ocorreu com a deriva nos estadios mais precoces, em ambas as especies. As doses de clomazone nao causaram qualquer sintoma detectavel visualmente para as plantas de beterraba e de cenoura. Os resultados sugerem que o herbicida glyphosate causa injurias as plantas de beterraba e cenoura, independentemente do estadio em que ocorre a interceptacao do produto. No entanto, o herbicida clomazone nao interfere no desenvolvimento inicial de plantas de beterraba e cenoura.

COMPETITIVIDADE RELATIVA DA SOJA EM CONVIVÊNCIA COM PAPUÃ (Brachiaria plantaginea)

The ability of a certain plant to compete with another one is related to factors such as species, population, emergence period and morphophysiologic characteristics. Experiments in substitution series allow the study of population effects and proportion of plants in species association, the importance of intra and interspecific competition and the ecological niche differentiation. The objective of this study was to investigate the competitive ability of soybean plants with the weed plant alexandergrass through the experimental method of substitution series. The experiment was carried out with a total population of 200 plants m -2 and proportions of 100:0, 75:25, 50:50 and 0:100 for soybean and alexandergrass, respectively, in a completely randomized design, with four replications. Competitive analysis was performed through diagrams applied to substitutive experiments and morphologic variables. Deviations observed in relative productivity lines and total relative production, in relation to expected linear lines, for both species, resulted in concave lines and smaller than 1, demonstrating antagonism in the growth of species in association. For soybean and alexandergrass, intraspecific competition was more important than interspecific competition. Key-words: Glycine max; interference; weed plant; relative variables.

Germinação e Crescimento de Biótipos de Fimbristylis miliacea Resistente e Suscetível aos Herbicidas Inibidores da Enzima Acetolactato Sintase

ABSTRACT - Weed biotypes resistant and susceptible to herbicides may have differences intheir adaptive values. The aims of this study were to compare, under controlled and non-competitive condition, the growth analysis, germination features and seed weight of Fimbristylismiliacea (FIMMI) biotypes resistant and susceptible to acetolactate synthase (ALS) inhibitingherbicides. Experiments were conducted in a greenhouse and in a laboratory from October2008 to February 2010. Two resistant biotypes (FIMMI 10 and FIMMI 12) and one susceptiblebiotype (FIMMI 13) were used for the studies. For the study on growth analysis, the treatmentswere arranged in a completely randomized experimental design with four replications andsampled at 21, 28, 35, 42, 49, 56, 69 days after emergence (DAE) and at flowering stage. Forthe studies on germination speed, germination and seed weight, the indexes for germinationspeed, percentage of germination at different temperatures and seed weight of the biotypeswere determined. The results showed that the resistant biotype FIMMI 12 shows differencesin all variables compared to the resistant biotype FIMMI 10 and compared to the susceptiblebiotype FIMMI 13, only for the evaluation at flowering. The susceptible biotype FIMMI 13showed a higher germination speed index and higher germination rate when compared withthe resistant biotypes. On the other hand, the resistant biotypes FIMMI 10 and FIMMI 12showed higher seed weight.Keywords: paddy rice, globe fringerush, Oryza sativa , herbicide resistance.RESUMO - Biotipos de plantas daninhas suscetiveis e resistentes a herbicidas podem apresentardiferencas quanto ao seu valor adaptativo. Os objetivos deste trabalho foram comparar, em condicaocontrolada e nao competitiva, a analise de crescimento, caracteristicas de germinacao e peso desementes de biotipos de Fimbristylis miliacea resistente e suscetivel a herbicidas inibidores daALS. Experimentos foram conduzidos em casa de vegetacao e em laboratorio no periodo de outubrode 2008 a fevereiro de 2010. Para os estudos foram utilizados dois biotipos resistentes (FIMMI 10e FIMMI 12) e um suscetivel (FIMMI 13). No estudo de analise de crescimento, os tratamentosforam organizados em delineamento completamente casualizado com quatro repeticoes e oito epocasde coletas [21, 28, 35, 42, 49, 56, 69 dias apos a emergencia (DAE) e no florescimento]. Quanto aosestudos de velocidade de germinacao, germinacao e peso de sementes, foram determinados osindices de velocidade de germinacao, porcentagem de germinacao em diferentes temperaturas e pesode sementes dos biotipos. Os resultados demonstraram que o biotipo resistente FIMMI 12 apresentoudiferenca em todas as variaveis avaliadas em comparacao ao biotipo resistente FIMMI 10 e, emcomparacao ao suscetivel FIMMI 13, apenas no florescimento. O biotipo suscetivel FIMMI 13apresentou maior indice de velocidade de germinacao e maior germinacao em porcentagem quandocomparado com os biotipos resistentes. Por outro lado, os biotipos resistentes FIMMI 10 e FIMMI 12apresentaram maior massa de sementes.Palavras-chave: arroz irrigado, cuminho, Oryza sativa , resistencia a herbicidas.

Controle de arroz-vermelho (Oryza sp.) com o herbicida nicosulfuron ou a mistura formulada de imazethapyr + imazapic

Red rice control efficacy using nicosulfuron or a formulated mixture of imazethapyr + imazapic was evaluated. A greenhouse experiment was carried out at Faculdade de Agronomia Eliseu Maciel (UFPel) in Capao do Leao (RS), during the 2005/2006 growing season, in a randomized complete block design and four replications. Treatments were arranged in a 2 x 7 factorial, with factor A being the herbicides and factor B the herbicide rates (0, 0.25, 0.50, 0.75, 1.0, 1.25 and 1.50 L ha-1). The herbicides were applied over red rice plants at the V4 development stage. Control, plant height and aerial dry mass were evaluated. There was a significant interaction for the variables between the factors studied. Increased herbicide rates resulted in increasing control responses and decreased plant height and dry biomass. Results showed that red rice is efficiently controlled by the herbicides. Control efficacy is not restricted to the formulated mixture of imazethapyr+imazapic, also occurring with nicosulfuron starting from 40 g ha-1.

Competition periods of crabgrass with rice and soybean crops

Determining the periods of weed competition with crops helps the producer to choose the most appropriate time to use weed control practices. This strategy allows for the reduction of the number of herbicide applications, reducing costs and the environmental impact of pesticides. The objectives were to determine the period before the interference (PBI) of crabgrass (Digitaria ciliaris) competing with flooded rice, the critical period of interference prevention (CPIP) of crabgrass with soybean and the effects of competition on the grains yield and their components. Experiments were conducted with the coexistence of BRS Querencia rice cultivar with crabgrass, for periods of 0, 7, 14, 21, 28, 35, and 110 days after emergency (DAE) and Fundacep 53RR soybean cultivar, whose periods of coexistence and control of crabgrass were 0, 7, 14, 21, 28, 35, and 156 DAE. Rice can grow with crabgrass infestation until 18 DAE, while soybean should remain free from the presence of crabgrass in the period between 23 and 50 DAE. The grain yield and its components, in the crops studied, are affected when grown with crabgrass.