Early sowing of canola has led to higher yields when using varieties with appropriate phenology, but with the introduction of HyTTec Velocity growers can sow canola at more traditional sowing dates and match or even better the grain yield of early sown canola. In fact, early sowing of HyTTec Velocity exposes the crop to a greater risk of frost, disease and lower yield compared with sowing at more traditional sowing dates.
To aid management decisions, it is important to understand that canola varieties are influenced by a mix of environmental factors which determine when a variety will reach certain physiological growth stages. These environmental factors include climatic factors such as mean daily temperature, cold accumulation (vernalisation), daylength and moisture.
Understanding how a variety is going to respond to the environment allows us to target the optimum flowering window, which will minimise the effect frost/heat/moisture stress will have on potential yield and performance. Sowing windows and emergence dates can be managed at a farm level to then target ideal flowering window for HyTTec Velocity.
HyTTec Velocity is a ‘spring’ canola variety that responds to temperature in a linear way, the warmer it is the faster it develops. When sown in late March or early April, development will be rapid and the crop will flower too early, exposing it to frost risk and disease risk that lead to potential lower yield. Many other Early/Mid varieties have a small vernalisation response which acts as a handbrake to slow them down when sown early.
For comparison on how fast HyTTec Velocity can be on a May emergence:
Due to the speed of flowering when sown early, HyTTec Velocity is highly susceptible to frost damage as the flowering window could be during the coldest period of the year, June to July. In targeting a flowering window of August by changing our emergence dates (sowing window), the impact of a cumulation of frost events can be minimised while still giving the variety enough time to flower and pod up before moisture and heat stress begins.
Frost damage in canola
Frost damage can influence the canola plant’s overall grain yield, oil content and oil quality during key periods of the plant’s physiological life. Damage can occur to canola plants during the flowering window and the pod/seed development window. The largest degree of damage to canola is during early pod development while pods have a high concentration of moisture, at this point damage is pod abortion. Frost damage later while pods have formed seeds is more likely to see damage to individual seeds and missing seeds in each pod, not full pod abortion.
Number of frost days in the east of Australia are highest in July. Most canola growing regions in Eastern Australia have an optimum start of flowering date very late in July to the first half of August. This is based mainly on weighing the risk of running out of moisture with frost risk.
Number of frost days in July:
HyTTec Velocity is a fast maturity product and the key flowering windows that should be targeted for the optimum performance in various regions is set out below. These flowering windows will attempt to minimise the effect a multitude of frosts can have on HyTTec Velocity while also giving the variety enough time to flower and pod up before heat and moisture stress becomes damaging. These flowering windows can be managed by moving the seeding operations and ultimately the emergence date of HyTTec Velocity. The following recommendations are based on the canola profitability work completed by GRDC in 2019.