Resposta da crotalária à épocas e subdoses de aplicação de glifosato

Abstract

The use of glyphosate sub-lethal rates can be an alternative to reduce the plant height of sunn hemp, facilitating its mechanical harvest. However, little known on the other effects that its application can result in this culture. This work aimed to evaluate the influence of application times (10; 20 and 30 days after the emergence) and glyphosate sub-lethal rates (0; 30; 60; 90 and 120 g ha-1), on the vegetative and reproductive development of Crotalaria juncea cultivated in no-tillage system. The experiment was conducted between the january and june months of year 2010, in Selvíria, Mato Grosso do Sul State, Brazil, on a clayey Rhodic Haplustox (20o 20' S and 51o 24' W). The experiment design was randomized blocks in factorial arrangement 3 × 5 (application times × glyphosate rates), with four replicates. Were measured agronomic characters and productivity and the results undergone to the test F, being the times averages compared by Tukey test (P<0.05) and of rates by regression analysis. The stem diameter, seeds number per pod and mass of one thousand seeds not were affected by glyphosate application. Despite the glyphosate have provided reduction in plant height and increase of the branches number in Crotalaria juncea, not recommended the sub-lethal rates application of product per of affect straightly the culture productivity.