Effects of Petiole Calcium Status, Petiole Location, and Plant Age on the Incidence and Progression of Soft Rot in Chinese Cabbage

Sand nutrient cultures (containing different Ca 2+ compositions) were used to modify the petiole Ca 2+ concentrations in Chinese cabbage ( Brassica campestris Group pekinensis). Petiole sections (6.5 cm 2 ) from inner and outer leaves, 30 and 60 days after transplanting, were inoculated with Erwinia carotovora ssp. carotovora to evaluate resistance to soft rot incidence and disease progression. Xylem exudates collected from the plants in the sand nutrient culture were analyzed for Ca 2+ concentration. Elevated petiole Ca 2+ concentrations were not correlated with the development of soft rot in inoculated petiole sections. Plant age and petiole position (inner and outer) did not consistently affect soft rot development. There was a trend of reduced soft rot in inoculated petiole (inner) sections of ‘Hakuran’ plants as the xylem exudate Ca 2+ levels increased.