Tiller population density and tillering dynamics in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization/Densidade populacional e dinamica do perfilhamento em capim-marandu submetido a estrategias de pastejo rotativo e adubacao nitrogenada

The objective of this experiment was to evaluate tiller population density and the dynamics of the tillering process in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization. Treatments corresponded to combinations between two targets of pre-grazing conditions (sward surface height of 25 and 35 cm) and two rates of nitrogen application (50 and 200 kg [ha.sup.-1] [year.sup.-1]), and were allocated to experimental units according to a 2 x 2 factorial arrangement in a randomised complete block design, with four replications. The following response variables were studied: initial (TPDi), intermediate (TPDm) and final (TPDf) tiller population density as well as the rates of tiller appearance (TAR) and death (TDR) and the tiller population stability index (SI). TPDi was similar to all treatments, with differences in tiller population density becoming more pronounced as the experiment progressed, resulting in larger TPDf on swards managed at 25 cm pre-grazing height. Tiller death was larger on swards managed at 35 cm, with differences in tiller appearance being recorded only from February 2010 onwards. Stability of tiller population was higher on swards managed at 25 cm pre-grazing height. Overall, there was no effect of nitrogen on the studied variables, and the most adequate grazing strategy corresponded to the pre-grazing height of 25 cm, regardless of the nitrogen application rate used. Keywords: management targets, nitrogen fertilizer, tiller population, grazing management, stability of plant communities. O objetivo deste experimento foi avaliar a densidade populacional e a dinamica do perfilhamento em capim-marandu submetido a estrategias de pastejo rotativo e adubacao nitrogenada. Os tratamentos corresponderam a combinacao de duas metas de altura pre-pastejo (25 e 35 cm) e duas doses de aplicacao de nitrogenio (50 e 200 kg [ha.sup.-1] [ano.sup.-1]) em arranjo fatorial 2 x 2 alocadas as unidades experimentais segundo delineamento de blocos completos casualizados, com quatro repeticoes. Foram avaliadas a densidade populacional de perfilhos inicial (DPPi), intermediaria (DPPm) e final (DPPf), as taxas de aparecimento (TAP), morte (TMP) e o indice de estabilidade (IE) da populacao de perfilhos. A DPPi foi semelhante para todos os tratamentos, com diferencas se acentuando ao longo da estacao de crescimento, resultando em maior DPPf nos pastos manejados a 25 cm de altura pre-pastejo. A mortalidade de perfilho