Abstract: A field experiment was conducted to study the responses of ramet characters of wild vetiver (Vetiveria zizanioides) population to planting density in western Guandong of China. On the 50 d (late October) and 240 d (next May) after planting, the ramet number of the wild vetiver population increased obviously. On the 270 d after planting, the ramet number under the highest planting density reached the maximum (821 ramets per square meter), which however  had no obvious inhibition effect on the increase of ramet number. On the 270 d (the beginning of June) after planting, the plot with a planting density of 80 ramets per square meter had significant differences in the numbers of no-jointed ramet, jointed ramet, and total ramet with the other plots. There was a significant linear correlation between the total biomass and the ramet number per square meter in all plots. The numbers of no-jointed ramet, jointed ramet, sexual ramet, and total ramet had significant positive power function relationships with the initial planting density. Though the planting density did not restrict the vetiver growth on the 270 d after planting, the increasing rate of ramet number was decreased obviously. The reproductive characteristics of the vetiver decided that the vetiver could still grow well at high planting density.

Key words: mixed plantation, sap flux density, rainfall pulses, environmental factor., Threshold-delay model