Effect of Varying Spacing and Pigeon Pea/ Maize Intercrop Patterns on the Weed Pressure, Growth and Yield Performance of Pigeon Pea across Diverse Agroecologies

Abstract

Pigeon pea productivity is often constrained by weed infestation due to its slow initial growth and wide plant spacing. Optimizing plant spacing in intercropping systems is therefore essential for enhancing yield, improving resource use efficiency, and suppressing weeds. This study evaluated the effects of plant spacing on pigeon pea–maize intercropping systems and associated weed dynamics in two agroecological zones: Ibadan (Forest–Savannah Transition) and Kishi (Southern Guinea Savannah–Northern Fringe). Two pigeon pea accessions (NSWCC-28 and NSWCC-50B), two inter-row spacings (1.0 m and 0.75 m), and intra-row spacing arrangements (0.25 m and 0.50 m for single plant stands, and 0.50 m for double maize stands) were evaluated in a split–split plot factorial experiment arranged in a randomized complete block design with three replications. Agronomic performance and weed growth parameters were assessed. Results showed that maize plants in Ibadan were significantly taller than those in Kishi at 12 weeks after sowing (WAS), whereas pigeon pea plant height did not differ significantly between locations. However, maize grain yield was higher in Kishi than in Ibadan, while pigeon pea grain yield in Ibadan was almost double that recorded in Kishi. Among accessions, NSWCC-28 produced higher grain yield and heavier seeds than NSWCC-50B, indicating superior performance in both sole and intercropping systems. Maize yield was higher under 0.75 m inter-row spacing, whereas pigeon pea performed better under 1.0 m inter-row spacing. Land equivalent ratio (LER) values indicated greater system efficiency in maize-dominated systems at 0.75 m spacing (0.98), while pigeon pea showed higher efficiency at 1.0 m spacing (0.95). The highest weed suppression was observed in treatments with 0.25 m intra-row spacing (single plant per stand). Overall, the study demonstrates that spatial configuration significantly influences crop performance, weed suppression, and resource use efficiency in pigeon pea–maize intercropping systems, highlighting its potential for reducing herbicide dependence and improving sustainable production.