Tipburn incidence in hydroponically-cultured Chinese cabbage is associated with temporal and spatial coorrdination of ROS regulatory systems

• Tipburn incidence is associated with spatio-temporal patterns of ROS accumulation. • SOD as well as APX and CAT play important roles to mitigate tipburn incidence. • Sequential application of pyridoxin and ascorbic acid efficiently mitigates tipburn. Hydroponic cultivation of crops offers a vital strategy for mitigating yield losses resulting from environmental fluctuations; however, it can lead to necrosis at the leaf apex, known as tipburn. To explore the mechanisms contributing to tipburn incidence, we compared two varieties of Chinese cabbage ( Brassica rapa L. ssp. Pekinensis ), Haru-torai (HT) and Haru-warai (HW), which have varying sensitivity to tipburn. HT showed higher sensitivity to tipburn compared to HW. Before tipburn incidence, HT exhibited a higher level of O 2 •– and lower activity of SUPEROXIDE DISMUTASE (SOD) compared to HW. A high accumulation of O 2 •– in HT was also observed especially in the tips of leaves during the tipburn incidence. Although H 2 O 2 accumulation was higher in HW compared to HT prior to the tipburn incidence, a higher level of H 2 O 2 was detected in the tips of leaves in HT compared to HW during the tipburn incidence. These results suggest that tipburn incidence is associated with the temporal and spatial coordination of ROS regulatory systems. This conclusion is further supported by the finding that the sequential application of pyridoxine and ascorbic acid prior to tipburn incidence effectively mitigates this physiological disorder, offering potential to enhance crop yield in controlled facilities.