Evaluation of Sample Preparation Practices Common with Differential Thermal Analysis of Grapevine Bud Cold Hardiness

Background and goalsDifferential thermal analysis (DTA) is a popular semi -automated method to determine the temperature at which plant tissues freeze. It is used to evaluate effects of environmental variables, genotypes, and agronomic practices on cold hardiness, and as an Extension tool to monitor cold hardiness and provide decision sup-port for growers of many specialty crops.Methods and key findingsThis study evaluated common approaches in sam-pling and preparation of dormant grapevine com-pound buds for DTA to provide a reference point as to which adjustments might cause excessive variation in subsequent data. Common adjustments in sample preparation, such as using foil packets, moistened tissue paper, or bud orientation, had no consistent effects on DTA values, typically result-ing in a variation of <1 & DEG;C. The same was true for storage (or shipping conditions) of 24 hrs or less, provided samples were maintained at low, but above -freezing temperatures (1.6 to 4 & DEG;C). Finally, influence of bud position along the length of the cane was also inconsistent.Conclusions and significanceThe robust nature of DTA for estimating grapevine cold hardiness offsets the potential impact of varia-tion introduced from different sample preparation methods. These results can help those wishing to develop DTA protocols or expand their capacity to conduct DTA analysis to design protocols to best suit their individual program needs. Consistency in DTA approach is likely more important than the specific methods used, especially when comparing relative differences in observed lethal temperatures.