Agronomy Degree Practice Exam

Canola has epigeal emergence. How does that affect canola's tolerance to frost/freeze damage relative to wheat?

1. Canola is less susceptible

2. Canola is more susceptible

3. Canola is not susceptible

4. There is no difference

The correct answer is: Canola is more susceptible

Canola's epigeal emergence refers to the way its cotyledons emerge above the soil surface, which can lead to its increased exposure to frost and freeze conditions compared to wheat, which has hypogeal emergence where the cotyledons remain below ground. In the case of canola, the young plants and leaves are more exposed to sudden drops in temperature, making them more vulnerable to frost damage. Frost damage typically affects the above-ground parts of the plant, including young leaves and buds, which are critical for photosynthesis and plant development. Therefore, the structure of canola's emergence means that it experiences frost damage more readily than wheat. This greater susceptibility can negatively impact canola growth and yield, particularly when it is actively growing and flowering in cooler conditions, unlike wheat that maintains better protection due to its underground germination. In contrast, wheat being less exposed initially with hypogeal emergence provides it with a better survival mechanism under similar frost conditions. Hence, the comparison between canola and wheat regarding frost tolerance highlights canola's increased susceptibility due to its growth habit.