DOI: 10.5281/zenodo.17108518
title: A simple prototype for assessing plant cold hardiness with differential thermal analysis

description: These datasets and associated program files support a manuscript to be submitted to HardwareX  journal titled:  "A simple prototype for assessing plant cold hardiness with differential thermal analysis" by John R Butnor, USDA Forest Service, Northern Research Station, Burlington, VT, USA.

They are structured into 4 zip files:

CR23X program files.zip contains program files associated with a Campbell Scientific logger CR23X

CR1000X program files.zip contains program files associated with a Campbell Scientific logger CR1000X

interpretation.zip contains files related to Differential Thermal Analysis interpretation. The R program used to generate self contained html fils for Differential Thermal Analysis (DTA) is named "DTA interpretation.R" and the associated data set is named "sample_data_09022025.csv". The generated files are:

"sample_data_09022025.pdf"

"temp_cleaned.csv"

"TEM_1_MAX_example_column_3.html"

"TEM_2_MAX_example_column_4.html"

"TEM_3_MAX_example_column_5.html"

"TEM_4_MAX_example_column_6.html"

"TEM_5_MAX_example_column_7.html"

red_spruce_example.zip contains R program, data and related outputs associated with a biological case example of DTA analysis with red spruce. The files are similar to those found in interpretation.zip above, but specific to the experiment described below:

Dormant buds of red spruce (Picea rubens Sarg.) were used to demonstrate the ability of the DTA prototype to detect exotherms produced by plant tissue at specific temperatures. On May 19, 2024, dormant red spruce buds were collected from 2 elevations (549 m and 1,067 m) on Mount Ellen in northern Vermont and one elevation (69 m) at the University of Vermont (UVM) Horticultural Education and Research Center in South Burlington Vermont. Foliage samples from 549 m and 1,067 m were also collected to utilize the remaining TEM wells. The samples were stored in a refrigerator until running the system the next day. The rationale of sampling trees at different elevations was to demonstrate that trees were becoming less cold tolerant in response to warming springtime ambient temperatures at each elevation. Accordingly, samples collected from a lower, warmer elevation would be less cold tolerant and therefore produce exotherms at warmer temperatures upon incremental freezing. Likewise, samples collected from a higher, colder elevation would be expected to more cold tolerant and exhibit exotherms at comparatively lower temperatures with controlled freezing.

The prototype was controlled by a Campbell Scientific Inc. (Logan, UT, USA) model CR23X datalogger with programs created with the ShortCut utility: *.SCW which summarizes all options selected in the ShortCut GUI, *.DEF defines the physical wiring locations on the logger and names the data output labels, and *.DLD which is the compiled machine language that is sent to and used by the datalogger. The prototype control program measures all TEMs every second, and logs maximum and mean millivolt values every 10 seconds.

A programable ultra-low temperature chamber (MC-812, ESPEC North America, Inc., 4141 Central Parkway, Hudsonville, MI 49426 USA) was pre-cooled to 4°C. The DTA prototype was placed in the freezer with red spruce tissue place atop TEMs and the control program was initiated. Once the champer temperature was steady, it was programmed to soak (hold constant) at 4°C for 12 hours and then ramp (controlled transition) temperatures down at a rate of -4°C per hour until -40°C was reached.  

The file headers in the attached dataset are: TIMESTAMP    RECORD    T65P_MAX    T65_MAX    T127_MAX    T109P_MAX    T109_MAX    Temp_1_MAX    Temp_2_MAX    T65P_AVG    T65_AVG    T127_AVG    T109P_AVG    T109_AVG    Temp_1_AVG    Temp_2_AVG

 The red spruce tissue sample placed on TEMs as follows:

T65P   buds collected at 1067 m

T65     buds collected at 549 m

T127   foliage collected at 69 m

T109P buds collected at 69 m

T109   foliage collected at 1067 m