How is fecundity affected by mowing in the tropical weed Stachytarpheta cayennensis (Verbenaceae)?

Abstract

The effect of mowing on the fecundity of the tropical weed Stachytarpheta cayennensis (Rich) Vahl. "gervão" was evaluated by simulating conventional mowing on plants grown individually in pots, in a greenhouse. Mowing was simulated by clipping plants at 12 cm from the soil surface at the beginning of the reproductive stage. Mowed plants were compared to unmowed ones grown under identical conditions. Starting 50 days after mowing, data on the number of flower-bearing spikes and branches per plant were collected every 20 days for 110 days. Mean spike length and the number of seeds per spike and plant were assessed 110 days after mowing. The number of branches per plant was negatively affected by mowing; however, the number of spikes per branch and the number of seeds per spike and per branch were higher in mowed plants. No significant differences between treatments could be detected on the final number of seeds per plant and on the mean spike length per plant. These results are discussed in relation to their practical significance.