Enhancing maize ( Zea Mays L.) resilience to climate change: The role of supplemental irrigation and fertiliser microdosing in improving grain‐filling rates of drought‐tolerant varieties in northern Benin

ABSTRACT Maize productivity depends on grain‐filling, which requires understanding the interactions among genotype, water and nutrient management. However, these interactions remain poorly investigated in Sub‐Saharan Africa (SSA). This study investigates the influence of supplemental irrigation (SI) and fertiliser microdosing on grain‐filling and yields of maize varieties. Field experiment involved three maize varieties (one drought‐sensitive variety: DMR‐ESR‐W; two drought‐tolerant varieties: TZE‐Y POP STR and 2000Syn EE‐W), two water regimes (rainfed vs. SI) and three fertiliser levels (unfertilised control, microdose: 25 kg N + 4 kg P + 8 kg K ha −1 and recommended: 76 kg N + 13 kg P + 25 kg K ha −1 ). The grain‐filling rate (GFR) reached 70 and 90 g day −1 under the rainfed and SI regimes, respectively. The GFR was higher in drought‐tolerant varieties (90–110 g day −1 ) than in drought‐sensitive varieties (70 g day −1 ). The effective grain‐filling duration and active grain‐filling period were 2 days shorter under SI than under rainfed conditions and 3–5 days shorter under drought‐tolerant varieties than under drought‐sensitive varieties. The highest GFR occurred under SI combined with mineral fertiliser. The optimisation of maize productivity in SSA will require breeding programmes to consider resource‐efficient practices, including SI and fertiliser microdosing.