Dr Jens Berger1, Dr Andrew Fletcher1, Mr Sam Flottmann1, Mr Adam Brown1, Dr Heping Zhang1, Jeremy Curry2, Mark Seymour2
1CSIRO, Wembley, Australia,
2DPIRD, South Perth, Australia
Canola production is becoming increasingly important in the high rainfall zone, where yield is determined primarily by biomass, trading off harvest index (HI). However, input management for high biomass production carries greater financial risk, particularly if rainfall is below average. Moreover, high biomass production can have negative consequences for growers, including harvesting difficulties associated with tall crops, high stubble loads and in-season water use, and increased Sclerotinia risk.
To understand grower capacity to influence the canola yield/harvest index trade-off we used a factorial range of agronomic and genetic levers to manipulate canopy size and yield potential in on-farm HRZ trials:
- Cultivar: high vigour (RR) versus low vigour (TT)
- Plant density
- Input levels (N x S)
- Early season grazing
These treatments had a huge impact on plant height (119-176 cm), biomass (8.2-15.7 t/ha) and yield (1.9-6.2 t/ha). Yield differences were driven by HI, while HI was dominated by genetics and its interaction with agronomy. HI was lower in RR than TT canola but there were important differences/interactions within both groups. High HI cultivars had stable HI that was not modified by agronomy (TT: Invigor 450 (35%), Hytech Trophy (34%); RR: GT 53 (32%), P45Y28 (29%)). Low HI cultivars (TT: P45T03 (29%); RR: H540XC (23%)) further reduced their HI in treatments that increased biomass. Experiments are currently underway to unpick this contrasting interaction.
By understanding biomass partitioning in canola we hope to de-risk production for growers giving them the tools to manage the canopy they require.
Jens has almost 30 years experience studying adaptation of dryland crops using a combination of physiology, genetics and agronomy. The CSIRO canola team has been using these approaches to focus on the performance of canola across Western Australian rainfall gradients.