CARACTERÍSTICAS AGRONÔMICAS DE CULTIVARES DE SORGO (Sorghum bicolor (L.) Moench) SOB TRÊS DOSES DE NITROGÊNIO

The objective of this study was to evaluate characteristics of four forage sorghum cultivars at three levels of nitrogen fertilizer in an Oxisoil. A randomized complete block design in a 4x3 factorial scheme (CMSXS 762, BRS 610, BR 700 and BR 506 hybrid cultivars combined with 50 kg.ha -1 , 75 kg.ha -1 and 100 kg.ha -1 nitrogen levels). A Tukey test was used for comparison of treatment means. The yields of natural matter, with general average 59.31 t.ha -1 , were significantly different among sorghum cultivars; but there was no difference caused by nitrogen levels in this trait. The dry matter yield mean (15.17 t.ha -1 ) did not differ among cultivars or nitrogen levels. As opposed, dry matter and panicle and stalk contents in the natural matter were different among cultivars as well as among N levels. The plant height (with general average 2.39 m) and stalk dry matter means were different only among cultivars. BR 700 and CMSXS 762 cultivars showed the best panicle/stalk/leaf ratio and the largest panicle percentage. Increased amounts of nitrogen resulted in increased panicle and decreased stalk percentage. KEY-WORDS: Sorghum; nitrogen fertilization; agronomic valuation.