Abstract: Genotypic diversity can generate soil legacies that strongly affect plant performance. Plant responses to these legacies may vary across ontogeny because growth is size dependent and soil effects often weaken through time, yet how plants adjust their development under such changing conditions remains unclear. Ontogenetic allometry offers a useful framework for understanding how plants modify growth strategies in response to soil legacies of genotypic diversity. Here, we grew × Bolboschoenoplectus mariqueter with varying genotypic diversity, to test how these soil legacies shape developmental timing and ontogenetic allometry. We found that soils conditioned by higher genotypic diversity accelerated the timing of peak height and ramet production, and increased both ramet and inflorescence output. These shifts in timing and magnitude were coordinated with shifts in ontogenetic allometry. The ramet-height scaling exponent declined in high diversity soils, indicating greater early investment in lateral clonal expansion relative to vertical growth, while inflorescence number continued to scale consistently with ramet number, allowing early clonal proliferation to enhance sexual reproduction. Our results show that soil legacies of genotypic diversity reshaped developmental timing and ontogenetic allometry, enabling plants to shift the timing of development and resource use, thus providing a mechanistic link between diversity and plant–soil interactions.

Key words: genotypic diversity, soil legacies, allometry, ontogeny, plant-soil interactions