Crop susceptibility to frost
All winter grain and oilseed crops are susceptible to frost. Crop selection is an important factor to consider for frost-prone paddocks. Hay production harvests biomass and hence reproductive frost damage does not reduce yield. Pasture rotations are a lower risk enterprise and oats are less susceptible to frost during the reproductive stage than other cereals. Wheat is more susceptible then barley at flowering, but it is not known if barley and wheat have different frost susceptibilities during grain fill. Canola is an expensive crop to grow and can increase financial risk on frost-prone paddocks due to high input costs.
Cereals
Oats are regarded as the cereal crop least susceptible to frost damage, followed by cereal rye, barley, wheat and triticale. Oats is thought to be about 4°C more tolerant than wheat while barley is thought to be about 2°C more tolerant than wheat.
| Crop in order of frost susceptibility (lowest to highest) | Notes |
|---|---|
| Oats | About 4°C less susceptible than wheat |
| Cereal rye | |
| Barley | About 2°C less susceptible than wheat |
| Wheat | |
| Triticale |
Canola and pulses
Canola is susceptible to frost, however is least susceptible to frost damage from late flowering (90%) to the clear watery stage (about 60% moisture).
Field peas are the most frost-susceptible pulse crop followed by faba beans and lupins.
| Crop in order of frost susceptibility (lowest to highest) | Notes |
|---|---|
| Faba beans | Faba beans have medium susceptibility to frost due to thick pod walls, which provide insulation to the developing seed. |
| Lupins | Lupins have a modest frost susceptibility and are generally able to compensate by extending flowering, if season length permits. After flowering during early pod fill, they are more sensitive. |
| Field peas | Field peas are highly susceptible due to thin pod walls and exposure of the pods to the atmosphere. |
| Chickpeas | Chickpeas are highly susceptible to frost due to the exposed nature of the flowers. |
Wheat variety response to frost
Under very severe frost (for example -8°C) or multiple minor frost (several nights of -2° to -4°C) all wheat and barley varieties are equally susceptible, resulting in up to 100% sterility. No varieties are frost tolerant however wheat and barley varieties do differ in susceptibility to reproductive frost damage during booting and flowering. Its important to note that there is no point selecting less susceptible varieties for the whole cropping program if there is an opportunity cost of lower yield without frost. A new variety should be managed based on how known varieties of similar ranking are currently managed.
Ranking information for current wheat and barley varieties for susceptibility to reproductive frost is available from the National Variety Trial website via the FV-PLUS frost rankings tool. These rankings are based on each variety’s relative susceptibility to spring radiation or reproductive frost, which occurs in late winter to early spring. As part of the Australian National Frost Program (ANFP – UA00136), 72 wheat lines were assessed and a nationally consistent methodology was developed to assess field based frost damage in cereals. The frost susceptibility data is generated from ongoing research trials based at Loxton SA; Merredin, Wickepin, Brookton and Dale WA; and Narrabri, NSW over several seasons.