Development of crop water stress index for kimchi cabbage precision irrigation control

This study was carried out to investigate the effects of soil moisture tension on the growth and leaf temperature of the Kimchi cabbage and develop the crop water stress index (CWSI) for precision irrigation control. Kimchi cabbages were cultivated under different levels (-20, -100, and -500 kPa) of soil moisture tension (SMT). At 60 days after transplanting, the dry matter weight was significantly lower at -500 kPa of SMT than -20 and -100 kPa, however, there were non-significant changes in the maximum leaf length, leaf width, and leaf number among SMT levels. The head weight of the Kimchi cabbage was 60% greater (2,331 g/plant) at -500 kPa than at -20 kPa (1,442 g/plant). The mean leaf temperature of cultivars at -20, -100, and -500 kPa during trial periods was 25.9, 26.5, and 30.6°C, respectively. The CWSI of cultivars at -20, -100, and -500 kPa was 0.0, 0.1, and 1.0, respectively. Results indicated that the growth, leaf temperature, and CWSI calculated from the leaf temperature of the Kimchi cabbage can differ depending on the SMT, and it is possible to develop feasible methods for precision irrigation using the CWSI.