Cold hardiness of 8 hybrid poplar clones for the introduction to arid and semi-arid areas.
Endodormancy is a key determinant of cold and freezing hardiness in plant cycles. Short plant growth periods and increasing frequencies of frosting caused by increasing temperatures are major environmental challenges faced by trees in arid areas of central Mongolia. In the present study, the primary aim was to determine an effective method for cold hardiness with the use of six introduced and two Mongolian poplar clones. The secondary aim was selecting clones suitable for afforestation in Mongolia. Year old branches were subjected to four temperature treatments to induce cold hardiness. Electrolyte leakage, 2,3,5-triphenyltetrazolium chloride (TTC) reduction, leaf sprouting, and leaf browning rates were compared. High rates of electrolyte leakage and browning rates were observed along with low leaf sprouting at a low-temperature of -30°C. Temperatures between -25°C and -30°C damaged certain clones more than others. TTC reduction rate method for determining cold hardiness was considered effective in this case. In addition, Mongolian poplar P. sibirica differed distinctly from other poplar clones owing to the difference in dormancy-breaking whereas DN 247 and DN sim were better adapted to cold hardiness based on TTC reduction rate. These findings suggest that factors such as plant dormancy depth and physiological differences might significantly affect productivity and performance among plants. Evidently, further studies are required using other plant parts for selecting suitable poplar clones.