Index of Injury Compared to Tissue Ionic Conductance for Calculating Freeze Damage of Cabbage Tissues

Abstract

The index of injury (I t ) and tissue ionic conductance (g Ti ) formulas for analyzing electrolyte leakage data from freeze-stressed tissues of cabbage ( Brassica oleracea L. Capitata group) were compared. The two formulas produced similar results in calculating the relative freezing responses of stem pith, lamina, and petiole tissues. Disagreement occurred only with lamina tissues when the magnitude of ion leakage was low. Vital staining of pith and petiole tissues with triphenyl tetrazolium chloride indicated that the tissue TK 50 (the temperature resulting in 50% injury), derived from I t data, was a reliable indicator of the freeze-killing point. These results support the use of the simpler I t method for analyzing electrolyte leakage data in studies of cabbage freezing tolerance.