Physiological and Morphological Responses of Soybean Culture Submitted to Applications of Glyphosate and Glyphosate + Flumioxazine

Abstract

Soybean (Glycine max (L.) Merrill) is one of the most important crops in the world economy. With the official release of glyphosate- resistant transgenic soybeans in 2005, profound changes in weed management systems are occurring. The objective of the present work was to evaluate the physiological effects caused by application of EPSPS inhibitor herbicide applied in isolation and in mixture with Protox inhibitor herbicide in RR soybean plants. The experiment was conducted in the experimental area of the Federal University of Tocantins, Gurupi University Campus. The material used for planting was the cultivar SYNGENTA 1183 RR. The experimental design was a completely randomized (DIC) arranged in factorial scheme 8x6 + 1, being 8 doses of herbicides in different concentrations (4 doses of glyphosate in the dosages 480 gia ha- 1; 980 gia ha-1; 1140 gia ha- 1; 1920 gia ha-1 plus four mixing doses of the glyphosate + flumioxazin herbicides at dosages of 480 + 20, 980 + 20, 1140 + 20 and 1920 + 20 gia ha-1) and the control (no application). After the application of the herbicides, 6 physiological evaluations were carried out, the first 5 days after the application and the others of 7 in 7 DAA. The parameters evaluated were: height, diameter, phytotoxicity, photosynthesis, stomatal conductance, internal carbon and transpiration The isolated glyphosate interfered in the growth of the plants with a reduction in height in relation to the control, with increasing doses. However in the mixture there was a significant difference and in the mixture of glyphosate + flumioxazin herbicides, there was reduction in the physiological parameters.