Effect of tillers on corn yield: Exploring trait plasticity potential in unpredictable environments

Long-term selection in maize (Zea mays L.) favored single-stalked phenotypes limiting vegetative growth. However, reduced plant densities create conducive environments to the expression of vegetative branches called tillers. Tiller expression has motivated discussions about its yield effect in variable environments, but tiller research is lacking for modern corn genotypes. The objectives of this study were to (a) quantify the relative importance of management, environment, and interactions on the yield effect of tiller expression for two modern genotypes; (b) understand effects of observed tiller density, plant density, and their interaction on yield; and (c) identify key environmental determinants of yield response to tiller density in modern genotypes. In 10 environmentally diverse site-years across Kansas, tiller presence and removal were evaluated in two commercial corn hybrids (P0657AM and P0805AM) across three target plant density levels (25,000, 42,000, and 60,000 plants ha(-1)). Yields were increased or unaffected by greater plant densities and tiller presence within site-years. Environments varied in yield responsiveness to tiller density, but fine-tuning plant density was needed to maximize yields. Sites with yields most responsive to tiller density were characterized by good soil properties and photothermal quotient values (e.g., soils with high organic matter and climates with greater solar radiation and cooler temperatures). Favorable growing conditions can be exploited by plasticity traits such as tillering in unpredictable environments with annually variable optimum plant densities while limiting potential yield loss and producer risk due to disproportionate plant density.

Automated summary

This study found that plant density and tiller presence significantly affect corn yield in different environments, and fine-tuning plant density is necessary to maximize yield. Sites with the strongest yield response to tiller density were characterized by good soil properties and photothermal quotient values.