Frost Resistance Rating of Winter Crops: Expert Outlines Limits of Endurance
During periods of sharp cold, farmers increasingly ponder the critical temperature thresholds for winter crops — wheat, rye, triticale, and barley. A detailed analysis of these indicators was conducted by Doctor of Agricultural Sciences Serhiy Avramenko, the leading research scientist at the V. Ya. Yuriev Institute of Plant Growing.
This is reported by AgroReview
Impact of External and Varietal Factors on Frost Resistance
To illustrate his point, Serhiy Avramenko cited the example of bamboo growing in the Kharkiv region: at an air temperature of minus 17 °C, the plant remains green. According to the scientist, this indicates the high adaptability of certain crops; however, the situation for winter crops may change with prolonged exposure to low temperatures.
“The critical temperature for the overwintering of winter crops depends on many other factors. In particular, the growth and development phase of the plant itself, its hardiness level, varietal characteristics, fertilization systems, and the conditions under which the crops were grown. Predecessors also have a certain influence. And, of course, the protection of the field from winds matters: whether there are tree belts or not, whether the field is exposed to winds, this is also important. Even the soil structure — whether it is sandy or heavy clay,” noted Serhiy Avramenko.
The specialist emphasized that the impact of each of these factors has been studied in various scientific works; however, their conclusions can be generalized into certain average values of winter crops’ frost resistance.
Comparative Frost Resistance of Main Winter Crops
Among winter crops, barley is the least frost-resistant. Its average endurance threshold is about –15°C at the depth of the tillering node, provided that such a temperature lasts no longer than one day. With longer frosts or in the absence of snow cover, plant death is possible even at –12°C.
Wheat ranks second in frost resistance. The type of variety plays an important role — hard winter wheat can withstand temperatures 1–2°C lower compared to barley, that is, up to –16–17°C. Soft wheat, depending on additional conditions, can endure up to –17–18°C.
Winter triticale demonstrates even higher frost resistance, surviving temperatures down to –18–19°C. The leader in this ranking is winter rye, which can survive at temperatures of –20–21°C.
The expert paid special attention to the influence of snow cover on the preservation of winter crops. According to him, every centimeter of snow provides additional protection for plants of about 1°C. Thus, with a 10-centimeter layer of snow at an external temperature of –20°C, the temperature at the tillering node will be approximately –8°C. However, if there is no snow, the soil temperature can be only 2–3°C higher than the air temperature.
An additional factor is the timing of severe frosts. If negative temperatures are recorded at the beginning of winter, plants endure them more easily than at the end of the season, when carbohydrate reserves are depleted and resistance decreases.
“The closer to spring the temperature drops to critical levels, the worse it is for the plants. That is, at the beginning of winter, wheat can withstand –20°C at the depth of the tillering node, but at the end of winter, it may die even at –15°C, because carbohydrates accumulated since autumn are already being used up, and frost resistance decreases,” emphasized the specialist.
Thus, the level of frost resistance in winter crops is a complex indicator determined by both varietal characteristics and agronomic conditions of cultivation, as well as the climatic features of the season.