Geospatial Assessment of Frost and Freeze Risk in `Changhowon Hwangdo` Peach (Prunus persica) Trees as Affected by the Projected Winter Warming in South Korea: I. Determination of Freezing Temperatures

We investigated the patterns of freeze injury in dormant `Changhowon Hwangdo` peach fruit by observing the extent of browning and germination of the branches that were treated with freezing temperature sets simulating the process of natural freezing incidences in orchards. Under the treatment of freezing temperature of , the browning ratios were 15% for flower bud and less than 3% for both leaf bud and cambium. Under the treatment, the browning ratios were 40% for both flower and leaf buds and 1% for cambium. The browning ratios were 86%, 68% and 40% respectively for flower bud, leaf bud, and cambium under the treatment. All the samples showed 100% browning ratio under the treatment. The budburst ratios of leaf buds were 85%, 66%, 32%, and 0% under the -15, -20, -25 and treatments, respectively. The branches of peach fruit treated with the same freezing temperature showed different responses depending on the sampling date. In January the browning ratio was low and the budburst ratio was high whereas in February the opposite was the case, showing vulnerability of peach trees to low temperature after endo-dormancy release.