Jeong Ukhan, Kim Dohee, Kim Sohyun, Han Seung Hyun, Cheong Eun Ju
Plant Genetics and Breeding Lab, Department of Forest and Environment System, College of Forest and Environmental Science, Kangwon National University, Chuncheon, Republic of Korea.
Forest Technology and Management Research Center, National Institute of Forest Science, Pocheon, Republic of Korea.
Front Plant Sci. 2025 May 12;16:1550748. doi: 10.3389/fpls.2025.1550748. eCollection 2025.
(Lamb.) Carrière, a valuable species for timber production and reforestation, faces challenges in large-scale seedling propagation due to its slow growth cycle and high susceptibility to environmental stressors. Early detection of drought stress is critical for preparing seedlings for harsh field conditions and for optimizing irrigation strategies. This study aimed to detect drought stress at an early stage in seedlings by integrating physiological traits with image-based phenotypic measurements, with a focus on needle angle dynamics under controlled drought and irrigation conditions. The apical needle angle of one-year-old seedlings was measured using ImageJ, while seedling-level analysis was conducted using PlantCV to collect data and extract relevant parameters. Statistical analyses were performed to evaluate temporal trends and to identify growth environment and physiological traits significantly influenced by drought stress. As a result, apical needle wilting and recovery, along with seedling-level image analysis (parameter: Center of Mass(y)), exhibited significant responses to drought stress as early as Day 2. This provides a non-destructive method for early detection, preceding observable changes in physiological traits such as chlorophyll fluorescence and needle temperature that responded to drought stress by Day 6, as well as before seedling mortality occurred. Multiple regression analysis indicated that, as drought stress progressed, solar radiation and thermal-related parameters (ФNPQ and needle temperature) emerged as key predictors of needle angle variation. Image-based approaches, including RGB and thermal imaging, proved effective for real-time stress monitoring, demonstrating their practical potential for nursery applications. In summary, this study lays the groundwork for needle-based phenomic approaches using imaging techniques in nursery systems and highlights the need for further research to optimize these methods for the large-scale, cost-effective production of high-quality, drought-resilient seedlings.
（Lamb.）卡里埃，一种对木材生产和重新造林很有价值的树种，由于其生长周期缓慢且对环境压力高度敏感，在大规模苗木繁殖方面面临挑战。干旱胁迫的早期检测对于使苗木适应恶劣的田间条件以及优化灌溉策略至关重要。本研究旨在通过将生理特征与基于图像的表型测量相结合，在幼苗早期检测干旱胁迫，重点关注在受控干旱和灌溉条件下针叶角度动态。使用ImageJ测量一岁幼苗的顶端针叶角度，同时使用PlantCV进行幼苗水平分析以收集数据并提取相关参数。进行统计分析以评估时间趋势，并确定受干旱胁迫显著影响的生长环境和生理特征。结果，顶端针叶萎蔫和恢复，以及幼苗水平图像分析（参数：质心（y）），早在第2天就对干旱胁迫表现出显著反应。这提供了一种早期检测的非破坏性方法，早于叶绿素荧光和针叶温度等生理特征在第6天对干旱胁迫作出反应的可观察变化，以及早于幼苗死亡发生之前。多元回归分析表明，随着干旱胁迫的进展，太阳辐射和与热相关的参数（ФNPQ和针叶温度）成为针叶角度变化的关键预测因子。包括RGB和热成像在内的基于图像的方法被证明对实时胁迫监测有效，展示了它们在苗圃应用中的实际潜力。总之，本研究为在苗圃系统中使用成像技术的基于针叶的表型组学方法奠定了基础，并强调需要进一步研究以优化这些方法，用于大规模、经济高效地生产高质量、抗旱的幼苗。
