Spatial pattern of windbreak effects on maize growth evaluated by an unmanned aerial vehicle in Hokkaido, northern Japan

摘要

Effects of tree windbreaks on crop production vary from field to field. However, considerable labor is required to evaluate the effects of windbreaks by conducting yield surveys in multiple fields. The present study aimed to clarify whether the spatial pattern of windbreak effects on maize growth can be evaluated using an unmanned aerial vehicle (UAV) in a field with a windbreak in Hokkaido, northern Japan. We mapped normalized difference vegetation index (NDVI) distribution in the field using a UAV and conducted micrometeorological observation and survey of growth and yield. We found that the windbreak positively affected maize growth by increasing soil temperature at 3-5 H (H=windbreak height) and negatively by shading at approximately 1 H. NDVI estimated using the UAV was high in June and low in September, suggesting that the growth rate of maize at 3-5 H was higher than that at 6-12 H. NDVI was significantly correlated to dry matter content of maize, although the area shaded by the windbreak during observation could not be used for analysis. These results indicate that a UAV was successful to grasp spatial pattern of windbreak effects on maize growth. This study shows the potential of a UAV to be useful for saving time and money when we evaluate the effects of windbreaks on crop growth.