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

Abstract

Background and goals Differential 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 support for growers of many specialty crops. Methods and key findings This study evaluated common approaches in sampling and preparation of dormant grapevine com-pound buds for DTA to provi de a reference poi nt as to whi ch adj ustment s mi ght cause excessi ve variation in subsequent data. Common adjustments in sampl e preparation, such as using foil packets, moistened tissue paper, or bud orientation, had no consistent effects on DTA val ues, typically result-i ng i n a vari ati on of <1 °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°C). Finally, influence of bud positi on al ong the l ength of the cane was also inconsistent. Conclusions and significance The robust nature of DTA for estimating grapevine cold hardiness offsets the potential impact of variation 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.