Canola response to plant density at Wubin 2013 trial report

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In this 2013 trial:

1. Hyola 404RR (RR = Roundup Ready) was the highest yielding canola variety and produced highest gross margins.
2. Open pollinated varieties GT Viper and ATR Stingray had higher economic optimum plant density than hybrid varieties Hyola 404RR and Hyola 450TT (TT = Triazine Tolerant).
3. RR canola provided better weed control than TT.


The canola industry in Western Australia is expanding in low rainfall areas. Primarily, growers choose open pollinated TT varieties. However breeding companies are favouring the development of hybrids in order to pay for breeding services. Hybrids provide growers with more vigorous seedlings, comparatively better plant establishment and generally higher yields. However growers have to purchase new seed of hybrid varieties every year in order to get these potential yield benefits. Seed for hybrid canola is approximately 25 times more expensive than the seed of open pollinated canola. Inevitably if growers are forced into hybrids they may wish to minimise seed costs by sowing at low densities.


To investigate the plant density response to yield and oil content of TT and RR hybrid canola in comparison with open-pollinated canola.

Trial details

Property Great Southern Agricultural Research Institute, Katanning, paddock 1
Agzone 3 Growing season rainfall (GSR) = 353mm
Soil type Loam (3.4% organic carbon)
Paddock rotation 2012 oats, 2011 lupins, 2010 oaten hay, 2009 canola
Sowing date 21 May 2013
Fertiliser (kg/ha) 100 Agstar (14.3% N, 14.0% P, 9.6%, 0.6% Zn )drilled below the seed at seeding, 120kg/ha of Muriate of Potash and 400kg/ha of gypsum (17% Ca, 14% S) topdressed over whole site four weeks after seeding

Treatment detail

32 treatments:

  • Two herbicide tolerant systems: Triazine Tolerant (TT) and Roundup Ready (RR) canola
  • Four cultivars:

TT = Open pollinated - ATR Stingray; and Hybrid - Hyola 450TT

RR = Open pollinated - GT Viper; and Hybrid - Hyola 404RR

  • Eight densities: 5, 10, 15, 20, 30, 40, 60, 80 plants per metre squared (plants/m2)
  • Trial design: split plot design, with herbicide tolerance (HT) as main plots and cultivars x eight plant density as sub plots

Replications: three

Assumptions used in gross margins

  • Oil bonus: +/- 1.5% per unit of oil (%) either side of 42%, with no oil ceiling
  • Additional costs: seeding, harvest, insecticides assumed to be $100/ha
  • Nitrogen costs: $1/kg, application costs $8/ha per application
  • RR costs: seed $31/kg, herbicides $28/ha
  • RR price: grain worth $479/t (CBH Pool Albany 5 Nov 2013)
  • TT costs: seed $2/kg, herbicides $47/ha
  • TT price: grain worth $502/t (CBH Pool Albany 5 Nov 2013)

Contact information

Mark Seymour
+61 (0)8 9083 1143
+61 (0)8 9081 3126