Evaluation of sweet potato (Ipomoea batatas) live mulch at different spacings for weed suppression and yield response of maize (Zea mays L.) in southwestern Nigeria

The use of living plants for ground cover management in food crops is very recent in spite of the fact that food crop production in chemically killed sod has been practiced for years. A randomized complete block field experiment was conducted over 2 years to evaluate the influence of sweet potato live mulch at different intra row spacings (60 cm×25 cm, 60 cm×50 cm and 60 cm×75 cm) on weed suppression and yield response of maize in southwestern Nigeria. Hoe-weeding once at 3 and 7 weeks after planting was included in the experimental set-up as the standard cultural weed control practice. Results indicated that all the spacing regimes tested significantly (P<0.05) suppressed weed growth and increased grain yield over the unweeded sole maize. Regressing weed growth parameters (Y) against decreasing intra row spacing expressed as increasing plant population density of the sweet potato intercrop (X) showed highly significant (P⩽0.001) negative relationships. Of the treatments tested, maize plus sweet potato at 60 cm×25 cm and weeding once at 3 and 7 weeks after planting (WAP) produced the highest yields, but bearing in mind the economics of labour input, weed control and yield, maize plus sweet potato at 60 cm×50 cm would appear to be the most promising of all the treatments. The results of this study further confirm the potential of sweet potato as a suitable crop for use as live mulch that can be effectively exploited for weed suppression and improved growth and yield responses in maize.