Lodicule Isolation and Morphometric Analysis During Rice Floret Opening

Background

In rice (Oryza sativa), the floret consists of the lemma, palea, stamens, pistil, and two lodicules located at the base of the ovary. Lodicules function analogously to petals [1]. During the flowering period, lodicules absorb water and undergo rapid swelling. The resulting increase in volume generates a mechanical force that separates the lemma and palea, thereby enabling floret opening and pollination. After pollination is completed, lodicules lose water and shrink, which promotes the inward repositioning of the lemma and palea and leads to floret closure [2].

Accurate characterization of lodicule morphology is essential for understanding the mechanisms underlying floral movement, reproductive development, and genotype-dependent variation. Therefore, quantitative analysis of lodicule morphology at defined time points provides valuable phenotypic information. However, lodicule analysis is often influenced by technical variability. Inconsistent sampling intervals, variation of spikelet position in panicle, tissue dehydration during dissection, and differences in imaging parameters can introduce measurement bias. Previous studies have shown that lodicule morphology is highly sensitive to developmental stage, genetic background, and sampling conditions, often resulting in substantial variation in morphometric measurements across experiments [3–5]. In addition, the lack of standardized morphometric criteria limits comparability across studies.

To address these challenges, we describe a workflow for lodicule morphological analysis based on fixed clock-time sampling. This method avoids reliance on subjective developmental staging and instead emphasizes controlled sampling intervals, standardized dissection procedures, and calibrated imaging and measurement settings. By minimizing experimental variability, this protocol enables precise quantification of lodicule length, width, and thickness and facilitates reliable comparison across genotypes or experimental conditions.