A quantitative staging system for describing rice panicle development and its application for a crop phenological model

Abstract

AbstractUnderstanding panicle development in rice (Oryza sativa L.) is vital for agricultural management, but accurate identification of this phenomenon is difficult as the panicle forms within the pseudostem. Here, we aimed to (a) develop a new quantitative developmental scale, floral stage (FS), describing the reproductive stages of the panicle from panicle initiation to heading, and (b) develop a crop phenological model to predict the FS using meteorological information. Using eight different cultivars, we investigated the internal and external characteristics of the panicle, such as morphological changes in the shoot apex, panicle length, plant age in leaf number, and distance between the auricles of the last two leaves. The stages were scaled linearly over time by assigning scores from 0 to 10. Thus, we developed an FS scale describing the morphological characteristics of the shoot apex in the early stages, and panicle length as well as external characteristics in the later stages. The FS scale is linearly related to the values of the developmental stage model parameterized by air temperature and day length. Utilizing this relationship, we developed a model for predicting the FS scale based on meteorological information. The proposed FS scale and its prediction model will enhance the understanding of rice panicle developmental processes non‐destructively and act as a stepping stone towards the quantitative evaluation of reproductive development in various crops.