Some aspects of plant resistance to negative temperatures on an example of soybean and oil flax

The urgency of spring crops breeding for increasing resistance to negative temperatures by the example of soybean and oil flax is caused by a large share of the arid regions of the Russian Federation, where the increase in productivity can be ensured by earlier planting and ripening periods before the summer droughts peaks. Soybean and flax varieties for very early planting should first rise and develop more actively in the early spring period against the background of low positive temperatures, and better tolerate early spring frosts. However, practical soy and flax breeding in this direction is hampered by insufficient knowledge of the mechanisms of cold resistance and almost complete absence of genetic sources of this trait. The best modern cold-resistant forms of soybean can withstand frosts to minus 5 °C, and of oil flax - to minus 20 °C. The degree of resistance to freezing of soybean and flax plants at these temperatures is determined by the presence of cryocolloidal components in its cytoplasm. Deeper (for soybeans below minus 6 °C, for flax below minus 15 °C) freezing leads to coagulation and sedimentation of cryocolloids after thawing of plants with a significant decrease in the concentration of cell sap. When determining the polarity of the surface charge of colloid micelles of the cytoplasm, colloidal solutions obtained from soybean and flax seed flour were used as model biochemical analogues. When studying its reaction with solutions of electrolytes, it was established that with the increase in the charge of cations from the monovalent cations Na+ to the trivalent cation Fe3+, the coagulation and sedimentation of the colloids increases. These facts indicate a negative surface charge of colloid micelles of aquatic flour extracts and colloids of the cytoplasm.