Effects of quantitative trait locus MP3 on the number of panicles and rice productivity in nutrient‐poor soils of Madagascar

The majority of paddy fields in sub‐Saharan Africa (SSA) are characterized by nutrient‐poor soils. In such fields, tillering in rice (Oryza sativa L.) plants is severely restricted, which results in a reduced number of panicles and thus a decrease in grain yield. In this study, we evaluated the effects of a quantitative trait locus (QTL), associated with number of panicles and referred as MP3, on rice growth and grain yield in nutrient‐poor soils in Madagascar. We used a high‐yielding rice cultivar, Takanari, and its near‐isogenic line bearing the MP3 allele (NIL‐MP3). A pot experiment with various P application rates demonstrated vigorous tillering in NIL‐MP3 compared to Takanari from the early vegetative stage even under low P levels. This led to enlarged leaf area and thus increased biomass. We then conducted multiple field trials with a total of 12 experimental conditions using the two varieties. The experiments led to a range of grain yield from 1.3 to 4.1 t ha−1 and a range in number of panicles from 107 to 270 m−2. The results revealed that NIL‐MP3 produced a greater number of panicles and spikelets m−2 (19 and 12%, respectively) than Takanari across all 12 experiments. Grain yield increased in NIL‐MP3 under some experimental conditions. This study is the first of its kind to demonstrate that MP3 increased number of panicles and spikelets and grain yield in the nutrient‐poor and low‐yielding soils of SSA. Thus, we conclude that MP3 could become a prominent genetic resource for the improvement of rice yields in SSA.