Intervalo HídrIco ÓtImo e Grau de compactação de um latossolo vermelHo...

RESUMO -A fim de avaliar o efeito do regulador de crescimento trinexapac-ethyl em diferentes doses e épocas de aplicação em dois híbridos de milho, instalaram-se dois experimentos em Ponta Grossa, PR, Brasil, no ano agrícola de 2010/11. O delineamento experimental foi o de blocos ao acaso, em esquema fatorial 4 x 4 (doses x épocas de aplicação), com quatro repetições. Os tratamentos constaram da aplicação do trinexapac-ethyl (Moddus ® ) nas doses de 0,0, 187,5, 375,0 e 562,5 g ha -1 nos estádios V2, V4, V6 e V8 do milho, nos híbridos Status TL e Maximus TLTG. Avaliaram-se características agronômicas, componentes de produção e produtividade. A época de aplicação do trinexapac-ethyl não afetou características agronômicas e a produtividade dos dois híbridos de milho. Em relação à dose do regulador, somente o Maximus TLTG mostrou aumento da largura e diminuição do comprimento das folhas com o incremento da dose do produto, sem efeitos substanciais nos componentes da produção e na produtividade. Os resultados mostraram pouca resposta dos híbridos avaliados à dose e época de aplicação do trinexapac-ethyl; ao contrário do trigo, o uso na cultura deve ser mais bem avaliado, especialmente em relação à dose do produto e à reação de híbridos.Palavras-chave: trinexapac-ethyl, Zea mays, produtividade.ABSTRACT -Aiming to evaluate the effect of different rates and application times of the growth regulator trinexapac-ethyl on two corn hybrids, two experiments were carried out in Ponta Grossa, PR, Brazil, in the agricultural year 2010/2011. The experimental design was arranged in randomized blocks in a factorial scheme 4 x 4 (rates x time) with four replications. Treatments consisted of application of trinexapac-ethyl (Moddus ® ) at the rates of 0.0, 187.5, 375.0, and 562.5 g ha -1 and corn stages V2, V4, V6 and V8 of the hybrids Status TL and Maximus TL TG. The agronomic traits yield and yield components were evaluated. Time of application of trinexapac-ethyl did not affect yield and agronomic characteristics of the two corn hybrids. In relation to the regulator rate, only Maximus TL TG responded to increased product rate, with increased leaf width and length, without substantial effects on yield and yield components. The hybrids showed little dose response to rate and time of application of trinexapac-ethyl; unlike wheat, the use of the culture should be further evaluated, especially in relation to the amount of the product and the reaction of the hybrids.

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The presence of volunteer corn plants in coexistence with soybean has been increasing since the introduction of glyphosate-resistant corn hybrids. This study aimed to evaluate the effect of interference of volunteer RR® corn plants at different densities on two RR® soybean cultivars. The experiment was conducted in Rio Verde, GO. The experimental design was a randomized block design in a factorial arrangement (2×5), with four replications. Factor A consisted of two soybean cultivars (BMX Potência RR® and M8210 IPRO®), while five densities of RR® corn plants per m2 (0, 4, 8, 12, and 16) were adopted for factor B. The following evaluations were carried out for soybean: plant height, SPAD index, percentage of interrow closure, shoot dry matter, first pod height, number of pods per plant, 100 grain weight, and grain yield of grains. Soybean plant height presented a linear and positive relationship with the increased density of corn plants. Shoot dry matter, 100 grain weight, number of pods per plant, and grain yield were negatively affected by the increased density of volunteer corn infestation. The soybean cultivar M8210 IPRO® was more susceptible to corn plant interference when compared to the cultivar BMX Potência RR®.

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