A well-developed root system is necessary for plant growth and sustentation, and, as a consequence, for high pasture yield. The objective of this experiment was to evaluate root characteristics in Brachiaria brizantha cv. Marandu in response to combinations of nitrogen and sulphur rates in nutrient solution. Ground quartz was used as substrate in a greenhouse experiment from September to December 2001. An incomplete 5² factorial was arranged in a randomized block design with four replications. The 13 combinations of nitrogen and sulphur were, in mg L-1, respectively: 14 and 3.2; 14 and 32; 14 and 80; 126 and 12.8; 126 and 64; 210 and 3.2; 210 and 32; 210 and 80; 336 and 12.8; 336 and 64; 462 and 3.2; 462 and 32; 462 and 80. Plants were harvested twice and, after the second harvest, roots were taken from the substrate and evaluated. Root nitrogen concentration and nitrogen and sulphur content depended on the interaction between nitrogen and sulphur rates. Nitrogen rate was determinant for the length, surface, dry weight, length:dry weight ratio, and sulphur concentration in the grass root. Root dry weight, length and surface and the total content of nitrogen and sulphur in the grass were significantly correlated.
Brachiaria brizantha; roots; nitrogen fertilization; sulphur fertilization
