Freezing point of water, water content and proportion of freezing water in Heracleum sosnowskyi plants

Method plant tissue of analysis using differential scanning calorimetry (DSC)

Differential scanning calorimetry was used to assess the risk of tissue plant damage by low negative temperatures. We measured the freezing point of water, the water content and the proportion of freezing water in plant samples using the DSC – 60 Shimadzu calorimeter (Japan). The samples were buds and seeds of Heracleum sosnowskyi (hogweed) plants. The samples were placed in an aluminum pan with a volume of 0.1 cm³. The sample was cooled at a rate of 1 °C/min from +5 °C to -30 °C. The water crystallization temperature was determined at the beginning of the phase transition peak. After measurements, the material was dried at 105 °C to a constant dry mass.

The following calculations were applied:

1. A – DSC data (water crystallization temperature, ºC);
2. B – wet weight sample (mg);
3. C – dry weight sample (mg);
4. D = B-C – (water content in sample, mg);
5. E – DSC data (heat from water freezing, mJ);
6. F= E× 335 – (frozen water in sample, mg);
7. 335 –The heat of frozen for wateris approximately (mJ/mg);
8. G = D-F – (non-freezing water, mg);
9. H = (100%/D) × F – (frozen water in sample, %);
10. I = (D/B) ×100 – (water content in sample, %);
11. J= D/C (mg H₂O/mg dry weight sample).

 The results of the analysis are presented in the file «The_results_DSC_analysis_of_buds_seeds.xls».

Measurements were carried out in September 2018. The samples were buds and seeds of Heracleum sosnowskyi (hogweed) plants. Geographical coordinates vegetation plants 61.645333, 50.733196.