Growth, Yield and Productivity of Maize + Cowpea Intercropping as Affected by Varietal Combination and Relative Times of Planting

Aims: Maize-cowpea intercropping has been identified as a sustainable practice for enhancing food security and resource efficiency in smallholder farming systems. This study investigated the effects of varying varietal combinations and relative planting times on growth, yield attributes, and productivity within maize-cowpea intercrop systems. Study Design: A 3 x 3 factorial laid out in a Randomized Complete Block Design (RCBD) with four replications. Place and Duration of Study: Mampong-Ashanti, located in the Forest–Savannah Transition Zone of Ghana, during the 2021 minor and 2022 major cropping seasons. Methodology: The study included four sole crops comprising three maize varieties and one cowpea variety. The treatments were: (A) three varietal combinations [(i) Abontem maize + Zamzam cowpea, (ii) Opeaburo maize + Zamzam cowpea and (iii) Omankwa maize + Zamzam cowpea] and three relative times of planting [(i) maize planted 2 weeks before cowpea (M2WBC), (ii) maize planted simultaneously with cowpea (SIM) and (iii) cowpea planted 2 weeks before maize (C2WBM)]. Results: The results showed that sole cropping of Opeaburo maize promoted earlier tasseling and silking, while cowpea flowered earlier when planted after Opeaburo. For vegetative growth, sole Omankwa and Opeaburo produced the tallest maize plants. Cowpea grown simultaneously with Omankwa or Abontem also recorded greater plant height. For yield and yield components, maximum maize grain yield during the 2021 minor season (4.16 t ha⁻¹) was obtained when Omankwa was planted two weeks after cowpea, while in the 2022 major season, sole Omankwa recorded the highest yield (2.94 t ha⁻¹). Cowpea grain yield peaked under sole cropping in the 2021 minor season (346.50 kg ha⁻¹) and under simultaneous planting with Opeaburo in 2022 (405.25 kg ha⁻¹). Land Equivalent Ratio (LER) indicated greater efficiency in Abontem + Zamzam when maize was sown two weeks before cowpea, and in Opeaburo + Zamzam under simultaneous planting. Based on these findings, planting Abontem maize either two weeks before or simultaneously with cowpea is recommended for farmers interested in maize-cowpea intercropping for higher yield. Conclusion: Varietal combination and relative times of planting had a varying effect on maize and cowpea growth and yield.