Root Research
Online ISSN : 1880-7186
Print ISSN : 0919-2182
ISSN-L : 0919-2182
Current issue
Displaying 1-2 of 2 articles from this issue
Mini Review
  • Shota TERAMOTO
    2024 Volume 33 Issue 1 Pages 7-14
    Published: March 20, 2024
    Released on J-STAGE: March 22, 2024
    JOURNAL OPEN ACCESS

    Root system is an important breeding target because it affects water and nutrient uptake. Improving the root system can enhance important traits such as fertilizer absorption efficiency and drought stress tolerance. However, root collection and measurement in soil are laborious and destructive, making root system not to be a priority target for breeding. This mini-review introduces recent research trends focusing on labor-saving root collection and measurement, and development of nondestructive measurement techniques. In root collection, steel monoliths and a backhoe were used to collect rice (Oryza sativa) roots to save labor. A monolithic study of rice cultivars worldwide quantitatively evaluated the differences in tiller numbers, correlated with root biomass, and crown root diameters among rice subpopulations. In root measurement, a deep learning-based image analysis was used to measure rice roots to save labor. The trench method is a technique to dig trenches next to crops to observe the distribution of crop roots in soil. By analyzing trench images with deep learning, distribution diversity of roots in soil of rice varieties worldwide was evaluated. In nondestructive measurement, image analysis software was developed to analyze X-ray CT (computed tomography) images. Optimal cultivation and imaging conditions were determined, and shape of root system was visualized and quantified from the CT images. As described above, the labor-intensive tasks of root system analysis both indoors and outdoors had been improved in efficiency. Using these techniques, breeding related to root systems is expected to be further promoted.

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  • Yoko KUROSAWA, Shigeta MORI
    2024 Volume 33 Issue 1 Pages 15-22
    Published: March 20, 2024
    Released on J-STAGE: March 22, 2024
    JOURNAL OPEN ACCESS

    Growth and adaptation of long-lived trees are supported by energy produced by whole-plant respiration. The energy is allocated to root and shoot for water and carbon acquisition, and the allocation changes during ontogeny according to body size. However, few empirical studies have investigated the respiration of root and shoot throughout ontogeny. We measured the respiration, fresh mass, and surface area of entire roots and shoots for 377 beech (Fagus crenata) trees, from germinating seeds to mature trees. On log-log coordinates, the root and shoot respiration rates versus whole-plant fresh mass were modeled by upward and downward convex trends, respectively. This was because root fraction in respiration increased during early growth stages and decreased in later stages. However, during early growth stage, increase of root fraction was more largely in surface area (max. 78.2%) than in respiration (max. 47.8%). These indicate that a rapid and low-cost increase of root surface area during early growth stage promotes shoot growth at later stages. In mature stage, declines of root growth toward an asymptote was followed by declines of shoot and whole-plant growth. Furthermore, the whole-plant respiration of beech were within the range of whole-plant respiration of seedlings to large trees of 51 species from Russia to Indonesia. This indicates that there is a general pattern in the scaling of whole-plant respiration that transcends phylogeny and environment. Here, we review the whole-plant level root-shoot relationships and explain the significance of whole-plant respiration, including roots, for understanding underlying mechanisms of tree growth.

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