Yeruga Crop Research’s Trent Potter, Naracoorte, SA.
PHOTO: Deanna Lush
The agronomic and economic benefits of buying commercial hybrid canola seed rather than retaining hybrid seed on-farm from a previous year has been demonstrated in a GRDC-funded trial.
Higher grain yields were achieved and infection levels of blackleg reduced when commercial hybrid seed was used. When retained seed was used, oil content was lower, as were financial returns.
Trials were conducted in 2012 as part of a GRDC Fast Track project in South Australia at Minnipa and Lameroo (low-rainfall zone), Bordertown (medium-rainfall zone) and Bool Lagoon (high-rainfall zone).
Yeruga Crop Research’s Trent Potter says the aim was to measure the effect of retaining hybrid sowing seed on plant vigour, internal blackleg infection, oil content and grain yield, compared with the original commercial hybrid bought from a seed supplier.
Hybrid seed assessed included Conventional (Hyola 50 at all sites and Taurus at Bool Lagoon), Clearfield® (45Y77, 45Y82, 46Y83 and Hyola 575CL) and triazine-tolerant (CB Tumby HT and CB Jardee HT). Each was trialled with and without a fungicide seed dressing.
Mr Potter says the differences in results between the hybrids are likely to be caused by the hybrid breeding system used by seed companies and the degree of heterosis (hybrid vigour) between the lines used to produce the variety.
Growth and disease
There was little variation in flowering date between the commercial and retained seed. Some hybrids showed reduced early vigour when sown from retained seed but the response was variable.
When it came to blackleg, several hybrids at Lameroo and Bordertown sown from retained seed showed increased internal infection. At Bool Lagoon there was no significant difference, while Minnipa was not tested.
With retained hybrids, a seed dressing – in this case Jockey® − was needed achieve a similar low level of blackleg as the new hybrid seed, except at Bordertown where very high levels of blackleg occurred.
Mr Potter says yields of the commercial seed were significantly higher than the retained hybrid seed at the three low and medium-rainfall sites. At Bool Lagoon, retained hybrid yields were only slightly lower (see Table 1). Overall, yields of the retained hybrids were seven to 17 per cent lower.
“Similar results have been shown in recent studies in Canada where a yield reduction of up to 13 per cent has been shown for retained hybrid canola seed,” Mr Potter says.
TABLE 1 Mean canola yield (kg/ha) for hybrid sowing seed in 2012, South Australia.
|Retained yield as a percentage
of commercial (%)
|Bool Lagoon (high-rainfall zone)
|Bordertown (medium-rainfall zone)
|Lameroo (low-rainfall zone)
|Minnipa (low-rainfall zone)
Oil content in the retained hybrids was significantly lower than oil from commercial hybrids by about 0.6 to 0.9 per cent at all sites (except Minnipa, where it was not measured) but protein content was not affected.
Costs and returns
In the trial, commercial hybrid seed made higher returns than retained hybrid seed. Based on a $600-per-tonne canola price, commercial hybrid seed averaged:
- $82 per hectare more than retained seed at Lameroo;
- $52/ha more than retained seed at Minnipa;
- $99/ha more than retained seed at Bordertown; and
- nearly $100/ha more than retained seed at Bool Lagoon.
However, the economic factors to consider when deciding whether to buy new commercial hybrid seed include oil content, seed preparation costs and yield potential.
The trial found the extra oil content of commercial hybrid seed was likely to give a $6/t premium over retained seed (calculated at standard contract rates of 1.5 per cent in price per one per cent of oil).
The cost of preparing retained hybrid seed was $6/ha in grading and seed dressing.
Therefore the additional cost of retaining hybrid seed for sowing ranged from about $12/ha to $18/ha, when canola was grown in zones where potential yield was 1t/ha and 2t/ha respectively. This extra cost takes into account the seed preparation cost and the foregone oil content.
The cost-benefit analysis is based on a price of $26/kg for hybrid seed.
Trent Potter, 0427 608 306, firstname.lastname@example.org
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