Description

ABSTRACT

Effective weed management is prerequisite for enhanced productivity of cowpea. Field experiments were conducted at the University of Calabar Teaching and Research Farm, during the 2014 and 2015 late cropping seasons, to evaluate the weed suppressive effects of inter-row spacing and weeding frequency on cowpea yield. Factorial combinations of three inter-row spacing regimes (60cm, 75cm, 90cm) and four weeding frequencies (no-weeding, weeding once, weeding twice and weeding thrice) were laid out in randomized complete block design, with three replications. Data collected on weed density (no m^-2), weed dry matter (gm^-2), number of branches plant^-1, yield parameters and grain yield (kgha^-1) were analyzed. Inter-row spacing at 60cm tended to suppress weeds more than spacing at 90cm apart, and produced significantly (P<0.05) higher grain yield than wider inter-rows. Weeding frequency profoundly affected weed growth and cowpea performance. On the two-year average, weeding once, weeding twice and weeding thrice reduced weed density by 16.86%, 33.58%, 45.55%, and weed dry matter by 46.49%, 54.19%, 57.93% respectively, compared with the weedy treatment. No-weeding significantly (P<0.05) retarded all yield attributes of cowpea and depressed grain yield by 24.03% averaged over the years, compared with weeded plots. Weeding thrice maximized the number of branches plant^-1 number of pods plant^-1, number of seeds pod^-1 and grain yield. The combination of 60cm inter-row spacing with weeding thrice, effectively suppressed weeds and produced consistently the highest grain yield (average 474.67 kgha^-1), and is therefore recommended for farmers growing Sampea 11 cowpea variety in the study area.

Keywords: Weed density, Weed dry matter, Weed suppression, Cowpea grain yield