HOW IS FECUNDITY AFFECTED BY MOWING IN THE TROPICAL WEED STACHYTARPHETA-CAYENNENSIS (VERBENACEAE)

The effect of mowing on the fecundity of the tropical weed Stachytarph eta cayennensis (Rich) Vahl. ''gervao'' was evaluated by simulating co nventional mowing on plants grown individually in pots, in a greenhous e. Mowing was simulated by clipping plants at 12 cm from the soil surf ace at the beginning of the reproductive stage. Mowed plants were comp ared to unmowed ones grown under identical conditions. Starting 50 day s after mowing, data on the number of flower-bearing spikes and branch es per plant were collected every 20 days for 110 days. Mean spike len gth and the number of seeds per spike and plant were assessed 110 days after mowing. The number of branches per plant was negatively affecte d by mowing; however, the number of spikes per branch and the number o f seeds per spike and per branch were higher in mowed plants. No signi ficant differences between treatments could be detected on the final n umber of seeds per plant and on the mean spike length per plant. These results are discussed in relation to their practical significance.