施設園芸環境下におけるコマツナの生育モニタリング手法の検討：草高推定を目的とした近接リモートセンシング技術の比較評価

抄録

In recent years, organic farming has been increasingly promoted in Japan due to a shift toward sustainable agriculture as well as the rising cost of chemical fertilizers. However, the nitrogen efficacy of organic materials shows considerable seasonal variation, complicating the adjustment of fertilization rates. This has resulted in farm management issues such as delayed crop growth and insufficient harvest volumes to meet contractual delivery requirements for leafy vegetables. To address these challenges, it is essential to record crop growth trajectories and biomass accumulation, and to develop fertilization management techniques based on historical data. In this study, we developed and validated a non-destructive monitoring method to capture temporal changes in the plant height of komatsuna (Brassica rapa var. perviridis) cultivated under greenhouse conditions. Four types of close-range remote sensing devices were used: a ropeway-type mobile imaging system, depth cameras, 2D light detection and ranging (LiDAR), and time-of-flight (ToF) sensors. Structure-from-Motion/Multi-View Stereo (SfM/MVS) analysis using the ropeway-type system achieved the highest accuracy in estimating plant height (root mean square error [RMSE]: 1.4 cm), enabling the visualization of growth heterogeneity across the field. The depth cameras also showed high accuracy (RMSE: 2.45～2.75 cm). The ToF sensors were effective for nighttime monitoring (RMSE: 3.83 cm), while the 2D LiDAR provided cross-sectional profiles of canopy height but had the lowest accuracy (RMSE: 4.96 cm). Continuous day-night monitoring confirmed the presence of a physiological response, circadian leaf angle changes influenced by light conditions, and showed that plant height continued to increase during the nighttime. These growth characteristics of komatsuna may affect the accuracy of plant height estimation.