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

Abstract

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.