The Wheat Genetic Improvement Network

Wheat is the major crop in the UK, with a total annual production of about 14,383 m tonnes from about 1.823m ha of land in 2016 (source: NationalStatistics_Dec2016). Wheat prices alter dramatically both between and within years, with highs often about £200 and £180 per tonne for milling wheats and food wheats, respectively, and lows about £70-100 per tonne and £65-90 per tonne, respectively. Lack of resilience in the wheat price and the lack of resilience in the wheat grain quality supplied is highly problematic to the industry. These fluctuations are primarily causes by annual differences in the weather, but some international factors can contribute in some years, i.e. maize prices, the quantities produced/available from other global regions. Since 2006, no two winter wheat growing seasons have been similar. Extreme weather events also occur, eg. in 2007, 2012 and 2015 high summer rain, in 2013 and 2016 exceptional cold springs, in 2013 summer drought and in 2016 low summer light. 

The wheat crop has a significant ‘environmental footprint’, particularly due to the requirement for substantial levels of nitrogen fertiliser, typically > 250 kg/ha. This fertiliser is essential to sustain current grain yields. Each year, British flour millers use approximately 5m tonnes of wheat of which ~85% is UK grown (~4.25 m tonnes). Additional nitrogen is provided to the crop to achieve the protein content required for bread making. This high nitrogen application can lead to losses into ground water and the eutrophication of rivers and lakes. In total, 370 tonnes is used in animal feed, an increasing volume is exported (~500 tonnes), 3% for seed production and 0.5% to other specialist uses. Increasing the industries serving the animal feed sector require and seek out wheat grain and wheat cultivars with improved feed quality and nutritional consistency. This demand trend is likely to continue.

High cereal yields are currently dependent on large inputs of fertiliser nitrogen which is expensive. However, high yields and consistent yields are an absolute requirement with current worldwide demands for grain. Developing wheat lines which give high yields over sites and seasons with appropriate N inputs is therefore a priority.

Another problem is that although the yields of newly bred and released elite wheat lines are increasing yearly at a rate of 0.1 tonnes/hectare extra yield per annum and routinely achieve >10.5 tonnes/hectare, this is not reflected in the average farm yields which are typically 7.5-8 tonnes/hectare. The potential for the UK to grow higher wheat yields on the same land and with similar inputs is illustrate by the fact that a Northumberland farmer currently holds the UK record at 16.52 t/ha (Dickens) achieved in 2015.

Currently the year to year variation in wheat yields is enormous. Although a lot of this variation is due to the weather, this long run of cultivar data obtained annualy within the WGIN project since 2003 for between 20 and 32 cultivars, clearly indicated that some genotypes exhibit a far lower level yield variation between season. Understanding the genetic basis of yield and quality stability is a very high research priority being addressed in this project in order to improve wheat crop resilience. Consistency of wheat performance (yield and quality) under varying climatic conditions is a major target for breeders and this requirement is expected to increase in importance under changing climatic conditions. 

Currently approximately 25% of the total UK wheat area planted is sown as second 2nd wheat crop and is at risk from severe losses due to take-all root disease caused by the fungus Gaeumannomyces tritici. This disease is responsible for reducing wheat yields by 1 tonne/hectare in 2nd wheat crops. There is no available genetic host resistance to this disease to help farmers achieve better control. Genetic resistance would provide a new way to control this disease, thereby improving the profitability of 2nd wheats and fertiliser usage. Most of the UK wheat crop is grown within the designated nitrate vulnerable zones. Maintaining a healthy wheat root system will help the crop cope with unpredictable weather events, eg. drought, heat stress.

The UK wheat crop is also heavily reliant on the use of pesticides/fungicides. A typical 1st wheat crop receives 3 sprays/season. Currently the most challenging problems are (1) aphid infestations, (2) Septoria leaf blotch disease and (3) yellow rust disease. Finding new sources of durable resistance to these pests and pathogens is a major target for breeders. By using genetics to protect the crop this should help improve wheat yield stability and quality in high stress years. 

The main abiotic risk to the UK wheat crop is temporary drought. If drought occurs for a few days around the time of crop anthesis up to 1 tonne/hectare can be lost. Identifying wheat genotypes that are resilient to temporary drought is a priority target for breeders. Drought resistance is likely to be a highly complex shoot-root trait. 

The novel traits under evaluation within WGIN are improving nutrient use efficiencies, improving the resilence of crop yield and grain quality, providing resistance to two species of aphids, Septoria leaf blotch disease, yellow rust disease and take-all root disease and improving resilience to temporary drought.