The optimal wheat flowering date for a given district, as well as the site within that area (for example, elevated hills or river flats), is an important cropping issue.
Subscribe now for unlimited access to all our agricultural news
across the nation
$0/
(min cost $0)
or signup to continue reading
There are many choices for different sowing time options that regularly occur, for example, depending on rainfall, it is valuable not only to select a variety with appropriate maturity for that sowing time but also to have knowledge of its likely flowering time.
Research of flowering time for a given variety at different sowing times has been conducted in many areas over the last four years.
An example of how this can assist with sowing decisions is detailed in the latest NSW DPI Winter Crop Variety Sowing Guide.
An example detailing flowering and yield responses to sowing time for a range of varieties is presented for Wagga Wagga, provided by Dr Felicity Harris (formerly NSW DPI) and Michael Mumford (biometrician Queensland Department of Agriculture).
Several varieties, varying from slow winter types to quick spring types, were sown from early April to late May across four seasons.
The optimal flowering period (OFP) for Wagga Wagga (whereby frost, heat and drought stress are minimised and yield maximised) was between September 26 and October 10.
Manning, a slow maturing winter variety, flowered later than the OFP for Wagga Wagga at all four sowing times, indicating it is unsuited to that environment.
It showed it is capable of higher yield in early sowings and is better suited to cooler areas (e.g. Tablelands) with a later OFP.
DS Bennett, also a slower winter type, also tended to flower later but had higher yield potential in the Wagga Wagga area.
Mid-winter types, such as Wedgetail and Kittyhawk, showed stable flowering responses to sowing time, flowering within the OFP.
Whilst flowering was stable, the yield was greater in earlier sowing dates, and there was a yield penalty as sowing was delayed after late April.
These results support the beliefs of pioneers of this style of winter wheat, Dr Albert Pugsley and Ron Martin.
In the 1960s, they released the first quicker maturing winter habit types, the forerunners of today's winter wheats.
Slow maturing spring varieties Nighthawk and Sunmax showed slower development and flowered close to the desired flowering window, although were not as stable as the mid-winter types.
Mid-spring varieties Gregory, Lancer and Coolah flowered too early when sown before late April, and yield was significantly reduced.
They were suited to a wide sowing window from late April to mid-May.
Trojan was slightly quicker developing, flowering early in April sowings, though flowered similarly in May sowing dates.
Showing there are differences between varieties rated similar in maturity, Catapult and Rockstar, which are mid-season rated, also flowered too early in the April sowing dates, and are better suited to sowing from late April - early May.
Beckom and Suntop, recommended for early May onwards sowing, flowered within the OFP for the May sowing dates.
They also tended to maintain high yields better than slower varieties from the later sowings.
Scepter and Reliant are rated slightly quicker than Beckom and Suntop and tended to flower quicker when sown before early-mid May.
They also maintained high yields in later sowing dates. Quicker varieties like Hellfire, Mustang, Condo and Vixon, flowered very early and had severe yield penalties when sown in April and best suited mid-May onwards sowing.
Multiple genes in any variety affect maturity (for example, daylength sensitivity, cold requirement), so matching a variety to its best sowing window varies from district to district as well as to a degree from year to year.
This research, based on four years of contrasting conditions, however, helps greatly to assist with variety choice.
More detailed regional research reports from this project can be found for southern NSW (dpi.nsw.gov.au/agriculture/broadacre-crops/guides/publications/southern-nsw-research-results) and northern NSW (dpi.nsw.gov.au/agriculture/broadacre-crops/guides/publications/ngrt-results).
Next week: Forty years of science-based agriculture in Down to Earth.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact 0428 752 149.
