Plasticity of Root Architecture Under Mixed Culture and Tiller Regulation in Sugarcane

Abstract

It is important for the effective use of soil resource and sustainable sugarcane production to study the root architecture and plasticity because soil resources are distributed unevenly. However, information on sugarcane root architecture and plasticity is limited because of its larger plant size and longer growth period. The mechanism of root formation is divided into internal (main stem and tillers) and inter-individual (sole and mixture) interactions. Our study attempted to reveal the effect of tiller regulation (internal interaction) and mixed cultivars (inter-individual interaction) on root formation in sugarcane. Tiller regulation decreased the total root biomass but distributed the roots in deeper soil, indicating that high-tillering characteristics may not necessarily contribute to a deeper root system and drought tolerance, at least during the early growth stages of tillers. Our results also revealed that the total shoot biomass, including the main stem and tillers, was not influenced by tiller regulation, suggesting a plasticity of shoot growth under tiller regulation. Roots under mixed cultivars grew well in the middle soil layer (20–50 cm depth) and were thoroughly distributed in each soil layer. These facts suggested that root habitat segregation of each cultivar may have occurred. Such root densification did not increase shoot biomass in the present study; however, it has the potential for improving lodging resistance and resource use efficiency under some abiotic stress conditions.