Soybean (Glycine max) cultivars sensibility to the herbicides diclosulam and flumetsulam

摘要

The objective of the present paper was to check the behaviour of 12 different soybean cultivars in relation to the tolerance to the herbicides flumetsulam and diclosulam applied on a soil classified as Latossolo Roxo distrófico (80,87% of clay, pH of 5,4 and 3,07 of organic matter) in Londrina - PR. The cultivars were: 'FTGuaira', 'Embrapa-48', 'Ocepar-14', 'BR-16', 'Embrapa-4', 'Ocepar-13', 'BR-36', 'FT 10- Princesa', 'FT-2000', 'FT-Abyara', 'BR-37' and 'RS 7-Jacuí'. Diclosulam was used in the rates of 35 g/ha (normal rate) and 70 g/ha (double rate) and flumetsulam in the rates of 120 g and 240 g/ha (normal and double rate respectively). It was also used a mix of diclosulam and flumetsulam (20 + 100 g/ha) and imazaquin at 150 g/ha. At the normal rates of both herbicides it was not poss to find any difference in suscetibily of the cultivars. At double rates of diclosulam the yields of 'FT-Guaira', 'Embrapa-4'and 'BR-37' were reduced in 20,9%, 11,8% and 11,0%, respectively, in relation to the check. Flumetsulam at 240 g/ha and its mix with diclosulam also reduced the yields of these cultivars, plus "Ocepar-14'. The major of the cultivars showed a reduced stand at the double rates of the both herbicides, but without significance. Only the stand of 'Embrapa- 48' was not affected, contrary to 'RS 7-Jacuí'. The plant height was reduced by flumetsulam at 240 g/ha. In all cultivars the nodule dry biomass was reduced in double rates, and in some of them the weight per unit of nodule. The dry biomass of aerial port and roots werw nor reduced.