Figure 1.

Inflorescence architecture in rice. A, Rice panicles are characterized by hierarchical transitions between meristems. Plant breeders often use the composite phenotype PL, even though it combines the length of the rachis axis (RL) with that of the terminal primary branch. Thus, several structural components should be accounted for when using image analysis to measure rice panicles. The panicle notch (red arrowhead) and IM abortion point (red arrowhead in B) denote the beginning and end of IM division, respectively. Multiple IM-to-branch meristem transitions can occur at a single internode point (red asterisk), and the distance between two such points can thus be defined as the NL. Measuring PBL is also important but can be complicated by the presence of awns and secondary branches. The vegetative phenotype EL is calculated as the distance from the flag leaf ligule to the panicle notch and is reflective of how far the panicle emerges from the leaf sheath during heading.