Maize (Zea mays L.) yield response to solar radiation in a rain forest location of sub-Saharan Africa

Abstract

This study tested the hypothesis that incident solar radiation, particularly during the grain filling stage, is a key determinant of maize (Zea mays L.) yield variability across different agro-ecologies. Experimental data on daily solar radiation and grain yield of five maize varieties planted weekly, from the onset to retreat of rainfall for two years at the Obafemi Awolowo University Teaching and Research Farm, Ife-Ife, Nigeria, were used to investigate the relationship of incident solar radiation and grain yield of maize in the rainforest region of South West Nigeria. Correlation and regression analyses revealed that solar radiation significantly (P ≤ 0.01) positively influenced maize growth and grain yield from approximately 30 days after planting (DAP), with a greater impact observed during the later stages rather than the early stages. Path coefficient analysis identified total solar radiation throughout the growth cycle as the most influential factor for grain yield. In contrast, stepwise multiple regression highlighted the importance of average solar radiation per day. Grain yield exhibited a linear relationship (R² = 0.4) with both average and total solar radiation beyond 31 DAP, particularly during the grain filling stage. The results further indicate that a consistent level of average solar radiation is more effective in promoting maize yield than intermittent high levels of total solar radiation.