Morphoagronomic traits of BRS 610 sorghum submitted to artificial defoliation

The objective of this study was to evaluate the agronomic traits of BRS 610 forage sorghum, based on developmental stages and defoliation levels. The experiment was conducted in a protected environment, located in Uniao experimental farm, in Nova Xavantina-MT, in vases with 8 dm-3 capacity in soil classified as dystrophic red latosol. The experimental design was a randomized block, arranged in a 4 x 3 + 1 factorial, four stages of defoliation [three expanded leaves (15 days after emergence of plants - DAE), six expanded leaves (30 DAE), panicle differentiation (45 DAE), booting (60 DAE)] and three levels of defoliation [(33, 66 and 99%) and an additional treatment without defoliation], making the total of 13 treatments with three replications. BRS 610 sorghum crop was used. It was evaluated plant height, stem diameter, root dry mass and shoot dry mass. Except for plant height and stem diameter, for the other variables there were significant influences of defoliation levels. To root mass and shoot dry mass it was verified that less intense defoliation and the early stages affect less those variables. To root dry mass, reductions are evident up to 66.36% when the plants are submitted to total leaves removal at the stage of panicle differentiation. The production of shoot dry mass of the BRS 610 sorghum is affected when submitted to any level and defoliation stage.   Key words: Forage, silage, Sorghum bicolor (L.) Moench.