Abstract

In Sierra Leone, weed management in upland rice production is a major constrain and yields are seriously reduced. Studies were conducted during the wet cropping season of 2007 and 2008 at Rokupr Agricultural Research Centre (RARC) in the upland ecology to assess the competitiveness of different rice varieties and to identify plant parameters responsible for their competitiveness. The results indicated that rice varieties differed in their competitiveness against weeds. Average yield losses ranged from 23 to 63% in 2007 and from 22 to 66% in 2008. Leaf area index (LAI) and tiller number with the exception of plant height correlated positively with competitiveness. The varieties NERICA 1, NERICA 6 and WAB 515-B-16A2.6 were found to be competitive and productive, whilst Buttercup (the local variety) though competitive but not productive. ROK 3 was the worse competitor but yielded similarly as NERICA 6 under weed-free conditions. The varieties NERICA 1, NERICA 6 and WAB 515-B-16A2.6 have potential in breeding programmes to increase their competitiveness without significantly compromising yields since they are both high yielding and competitive.

Key words: Varieties, competitiveness, LAI, tillers, yield, plant height, weed-free.