Abstract
This study was conducted to estimate the difference of water stress for soybeans between irrigated and unirrigated blocks depending on the leaf temperature using a thermal image sensor mounted on unmanned aerial vehicle. According to the irrigation method, when there was rainfall (Aug. 8, Sep. 6, Oct. 4) or the soil moisture level did not drop below 25% (Sep. 20), there was no significant difference in leaf temperature. However, there was a significant difference in leaf temperature when there was no rainfall for a certain period (Aug. 1 and Aug. 19). There were significant differences in fresh and dry weight on Aug. 8, Aug. 19, Sep.20 depending on the irrigation method except for Aug. 1, when the application time of the automatic irrigation system was short. There was no difference in fresh and dry weight with or without irrigation due to the difference in recovery ability from water stress (Sep. 6) and rainfall (Oct. 4). Fresh weight, dry weight, and moisture content did not clearly depend on water stress because of soybeans' growth variability among the blocks. However, there was a significant negative correlation between soybean leaf temperature, fresh weight, and dry weight. Soybean vegetation was significantly reduced when damaged by water stress.
Figures & Tables
Fig. 1. Test field with automatic irrigation system (6 blocks without irrigation).
