Strigolactones (SLs) are hormones essential for plant development and environmental responses. SL perception requires formation of the complex composed of an SL receptor DWARF14 (D14), F-box protein D3 and transcriptional repressor D53, triggering ubiquitination and degradation of D53 to activate signal transduction. However, mechanisms of SL perception and their influence on plant architecture and environmental responses remain elusive and controversial. Here, we report that key residues at interfaces of the AtD14–D3–ASK1 complex are essential for activation of SL perception, discover that overexpression of D3-CTH motif negatively regulates SL perception to enhance tillering, and reveal importance of phosphorylation and N-terminal disordered (NTD) domain in mediating ubiquitination and degradation of D14. Importantly, we further show that low nitrogen promotes phosphorylation and stabilization of D14 to repress rice tillering. These findings reveal a panorama of the activation, termination and regulation of SL perception, which determine plasticity of plant architecture in complex environments.