Effect of paraquat as post emergence herbicide on yield of cowpea (<i>vigna unguiculata</i> (l) walp).

Abstract

The experiment reported herein was undertaken to determine the toxicological effect of paraquat as post emergence herbicide on yield of cowpea. Two rates of paraquat 0.50 kg ai/ha and 1.00kg ai/ha were applied as post emergence herbicide in pot experiment with fallow weed population; which examined the effectiveness for the control of weeds in cowpea. Information was obtained on the weed weight and yield components of cowpea as influenced by the paraquat herbicide. The results showed that there were significant differences (P < 0.05) in yield components of cowpea and weed biomass (weed weight). There was an adequate weed control achieved by paraquat treatments evaluated until 6 weeks after planting (WAP). The unweeded control or treatment had significantly higher (P < 0.05) weed biomass (weed weight) that all other treatments. The cowpea grain from pots that received paraquat at 1.00 kg ai/ha were 2 times more than that from the unweeded control. However, the highest yield of cowpea was obtained from handweeded control pots; the unweeded plots gave the poorest yield. Cowpea yield from paraquat herbicide treatments compared favourably with the yield realized from the handweeded control. Paraquat is therefore, effective for weeds in cowpea without adverse effects at the evaluated rates.