Structural Volume Composition of Internodes is a Key Morphological Factor Contributing to Culm Non-structural
Yu Wakabayashi1, Naohiro Aoki2, Ryutaro Morita2
1Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Midoricho, Nishitokyo-shi, Tokyo, 188-0002, Japan. aywakabayashi@g.ecc.u-tokyo.ac.jp.
Rice (New York, N.Y.)
|July 4, 2026
Summary
Rice stem carbohydrate storage is key for yield. This study found the volume composition ratio of upper to lower internodes (UIN/LIN VCR) is a reliable indicator of non-structural carbohydrate (NSC) accumulation capacity.
Area of Science:
- Agricultural Science
- Plant Physiology
- Crop Science
Background:
- Non-structural carbohydrates (NSC) in rice stems are vital for yield.
- Understanding internode morphology's role in NSC accumulation is crucial for crop improvement.
Purpose of the Study:
- To investigate the relationship between rice internode morphology and NSC accumulation.
- To identify a robust morphological indicator for assessing NSC accumulation capacity in rice.
Main Methods:
- Field experiments over two years with multiple rice cultivars.
- Quantification of NSC content at individual internode and whole-culm levels.
- Analysis of correlations between internode morphological traits and NSC content.
Main Results:
- Upper internodes (UIN) and lower internodes (LIN) have distinct roles in NSC accumulation.
- A novel index, the volume composition ratio (VCR) of UIN/LIN, strongly correlated with culm NSC.
- The UIN/LIN VCR demonstrated high reproducibility and outperformed simple morphological traits.
Conclusions:
- The UIN/LIN VCR is a robust morphological indicator for rice stem NSC accumulation capacity.
- This finding offers a practical approach to enhance carbohydrate storage in rice.
- Plant growth regulator treatments affecting VCR also impacted NSC accumulation, validating the index.
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