Changes of Growth and Hyperspectral Reflectances in <i>Paspalum distichum</i> <scp>var.</scp> <i>indutum</i> Under Different Water and Nutrient Conditions

ABSTRACT Paspalum distichum var. indutum is an invasive species problematic in South Korea, particularly in river basins. The study aimed to determine how soil moisture and nutrient conditions affect its growth. Experiments involved moderate moisture (T1), flooding (T2), flooding with nitrogen (T3), and flooding with nitrogen and phosphorus (T4). The research found that P. distichum var. indutum grew better under flooded conditions (T2–T4) compared to nonflooded conditions (T1), with the best growth observed in T4 due to increased plant height, root number, and stem thickness. Photosynthetic rate and aboveground biomass were highest when both nitrogen and phosphorus were present under flooded conditions. The presence of other plant species was greater in T1 and T2, indicating that as P. distichum var. indutum became more dominant, the diversity of other species declined. Vegetation indices calculated with hyperspectral reflectance were highest in T1 during the initial growth after transplanting. Among the vegetation indices, EVI, PSSRa, PSSRb, and PSSRc functionally assessed the growth status of P. distichum var. indutum under various growing conditions. P. distichum var. indutum requires flooding conditions for vigorous growth, and when nitrogen and phosphorus are sufficient, it grows more robustly than other plant species. Therefore, controlling the influx of nutrients is required to prevent the proliferation of this invasive species along this riverside.