AgMemo Central Agricultural Region

How to dry seed and yet create flowering spread

Dr Darshan, Sharma Senior Research Officer at DAFWA, showing flowering spread in opening rain scenarios created on dry sown wheat, at Merredin Field Day, September 2015

Building and protecting yield potential are both critical to the success of a cropping program.

There is about a three week flowering period every season that corresponds to maximum yield potential but, unfortunately, this period often coincides with low temperature events that can be detrimental to yield.

Damaging effects from low temperatures can vary from floret sterility to catastrophic frosts.

The overall impact on grain yield depends on the minimum temperature, its duration and crop variety.

A desirable strategy is therefore to spread this risk by creating flowering spread (FS) so as to build yield potential by hitting the flowering window (FW), while reducing the probability of the whole cropping program getting wiped out by frost.

Creating FS is more critical for early sown crops, as the yield potential is generally higher.

Hence, it is important to develop a good seeding schedule.

Developing a seeding schedule involves two steps:

Step 1: determine variety specific sowing dates for the high yield potential window

Step 2: tailor FS within this window

Determining variety specific sowing dates for high yield involves looking up sowing dates corresponding to your FW. 

Table 1 provides an overview of optimum FWs for wheat growing areas in WA.

To obtain flowering date predictions for your location and variety refer to the on-line tool Flower Power.

As an example, sowing dates corresponding to the FW at Merredin are shown for some varieties.

Sowing dates corresponding to optimum flowering window (05 Sept – 25 Sept) of six varieties at Merredin.

Tailoring a desirable FS is easy once variety specific optimum sowing dates have been determined.

However, it is a bit tricky for dry sown programs given the uncertainty of the date of opening rains.

The rule of thumb is to start dry sowing with the longest season variety and move sequentially to the next shortest season variety as the calendar date hits their respective sowing windows.

Once the opening rains arrive determine the predicted flowering dates for paddocks that were dry sown and plan the remaining cropping schedule accordingly.

The below graphs depict how changing from long-season (Yitpi) to mid-season (Mace) and then to short-season (Westonia) can disperse flowering dates of the dry-sown cropping program at Merredin.

Sowing spread using one, two or three maturity classes in a dry sown program at Merredin. The flowering date predictions have been taken from Flower Power.

For more examples of variety choice for different opening rains scenarios for Merredin refer to 2016 Grains Research and Development Corporation (GRDC) Research Updates paper- Sharma et al choosing crop variety for dry sown wheat crops.

The purpose of these choices is to show a framework for developing dry seeding schedules rather than recommendation of any varieties, proportions or sowing dates.

Seeding schedules that generate FS can be successfully created for dry-sown cropping programs.

The strategy is to dry-sow part of the schedule by calendar date and wet-sow the remaining schedule by matching varieties to predicted flowering dates (after considering the predicted flowering date for the dry-sown part of the cropping program once it rains).

For for information contact Dr Darshan Sharma, Senior Research Officer, Northam on +61 (0)8 9690 2188 or +61 (0)408 008 492.