The definition of that variability is the gap between a variety’s genetic yield potential and the yield observed on-farm at harvest, which can be influenced by a considerable number of factors.
Environmental influence
The environment is the first major influence; namely, moisture and sunlight through the growing season. Secondly, the farm’s agronomic practices will also impact on how much of the theoretical yield potential is achieved. When these two are in the grower’s favour, with good weather allowing all inputs to be carried out in a correct and timely manner, actual performance should be close to the variety’s genetic potential.
However, extremes in weather that hinder crop development, timely operations, or pressures from pests and disease, can widen that gap considerably, says Limagrain’s European Portfolio Manager for oilseed rape; Dr. Vasilis Gegas.
This in-field variability can be exacerbated by fluctuations in commodity prices and input costs, so when yields and prices are low and costs are high, profitability can be slashed.
“Farmers are really concerned about this variability, and there are two ways that we are helping to control it through our breeding programme,” he adds.
Made in the UK
The first of these solutions is selecting varieties adapted to local environmental conditions at the earliest stage, so a variety spends many years – from the beginning of the breeding cycle all the way to National List trials, in the UK.
“Limagrain has a network of trial sites around the UK for screening, making its varieties inherently more stable under UK conditions.”
“It allows us to weed out varieties that go up and down like a yoyo and ensure we only place the most stable into National List trials and subsequently into the market,” explains Dr. Gegas. The second area where breeders can help growers tackle yield instability is introducing genetics that makes a variety more resilient to the environmental and agronomic pressures, across a variety of seasons.
Mitigating oilseed rape variability
Yield variability caused by several environmental and agronomic factors:
- Commodity and input price fluctuations can hit profitability
- Breeders are “stacking” traits to help growers protect yield, in different seasons
- Pod shatter and Turnip yellows virus resistance is now standard in all Limagrain hybrids
- Clubroot and verticillium wilt resistance in 1-3 years
- All resistance traits will be in single varieties, without the ‘yield drag’ of past offerings
Limagrain is using precision breeding techniques to achieve this, and one example is ‘pod shatter resistance’, which is now standard in all LG’s hybrids.
Although the risk of untimely pod shatter won’t be high every year, this trait will provide good insurance if inclement weather does strike before the crop is safely in the shed. Pod shatter also protects from losses during harvest (as the header hits the crop) and also reduces the number of volunteers.
Turnip Yellows Virus
Similarly, Turnip yellows virus (TuYV) spread by Myzus persicae, is not endemic every season, but when aphid pressure is high and prolonged during the season, infection is difficult to prevent with foliar insecticides alone, and this can significantly penalise yield.
From introducing the trait in the variety; Amalie, in 2014 – which was less than 100% of controls on the Recommended List at the time – it is now standard in all Limagrain hybrids, and is included in Candidates; Ambassador and Aurelia, which both have significantly higher, competitive yield.
“When we started working with these traits, there was a trade-off – essentially, they were suppressing yield.” “Within five years, we moved from the bottom of the RL, with a TuYV resistant variety, to the top, by a country mile,” explains Dr. Gegas.
Disease resistance
Other traits built into the breeding programme include the RLM7 phoma resistance gene, which provides stable resistance scores of 7 or 8, and Limagrain does not offer varieties with a Light Leaf Spot score of below 6.
Dr. Gegas notes that phoma can be easily controlled with available chemistry, but Light Leaf Spot resistance is becoming increasingly important, as fungicide efficacy declines.
This, along with pod shatter and TuYV resistance all in one place, sees agronomic insurance built into Limagrain varieties, with inherently stable genetic yield potential for UK conditions.
“Examples include Ambassador and Aurelia, which are the first hybrids that really show the benefits of such a breeding strategy – inherently very high yield potential coupled with a bundle of traits that ensures growers shouldn’t lose yield in unfavourable conditions,” he adds.
Future traits
Looking ahead, Limagrain is focused on bringing clubroot and verticillium wilt resistance into its material.
A variety with high yield, which incorporates pod shatter, TuYV and clubroot resistance, is expected within the next year.
“Already, some of our hybrids are good on verticillium wilt, but we are working to develop traits that we can really call ‘resistance’, which are about 2-3 years away,” says Dr. Gegas.