Statistical analysis of the development of internal browning in Japanese radish [Raphanus sativus] in relation to thermal condition using logit model

To clarify the correlation between the occurrence of internal browning (IB) in Raphanus root and the thermal condition, especially, during the later growth period, a logit model was established, using the severity of IB in plant grown under different covering materials along with air and/or soil temperature data. Analytical results demonstrated that independent variables of 35 deg C for maximum air temperature or 29 deg C for maximum soil temperature were the most adaptable. The percentages of correct predictions using those models were high, ranging from 80% to 90%. These observations strongly suggest that the severity of IB is closely correlated with thermal conditions during the later growth period, and could be controlled by changing these conditions.