Despite achieving some of the highest average grain yields globally, improvements in the profitability and sustainability of winter wheat and spring barley production systems in Ireland are vital to ensure the future viability of these crops. Traditionally, variety selection has resulted in increases in yield that reflected the selection of traits that reduced a crop’s susceptibility to factors limiting yield, such as disease and lodging.

However, in recent times, the average yield of winter wheat and spring barley, which have increased annually since the 1960s, has begun to plateau. This may be a reflection of a reduced ability of new varietal and technological developments to overcome the remaining factors limiting the yield of cereals in Ireland.

Furthermore, grain price volatility has further highlighted the need to minimise crop input costs for producing a tonne of grain. Therefore, tillage farmers require applicable methods to maximise efficiency and we may not be fully exploiting the genetic potential of some varieties to maximise the economic return from cereal crops.

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Studies being conducted as part of the Department of Agriculture-funded project entitled Cereal Improvements Through Variety Choice and Understanding Yield Limitations (CIVYL) aim to investigate methods to increase the viability of winter wheat and spring barley production through three main steps: gain a more detailed understanding of these crops’ growth and development; estimate the maximum potential yield attainable across Ireland and identify the factors preventing these yields from being achieved; and finally investigate the potential of variety characteristics to allow for a more targeted use of crop agronomic inputs to maximise economic return.

Yield v Margin

The detailed monitoring of winter wheat and spring barley at sites around Ireland allows for the identification of the most important factors that influence the yield of the crop.

For example, recent monitoring of spring barley crops in Ireland has identified grain number/m2 as being closely related to grain yield, with ear number/m2 the primary factor influencing grain number. Therefore, maximising tiller production and survival during the early stages of spring barley development is critical to maximise yield.

However, maximum yield may not always result in maximum economic return. In situations where crops are achieving yields relatively close to their potential, further improvements in profitability can only result from increased efficiency of the agronomic inputs.

Every agronomic input will have an optimum rate whereby a further increase in application does not promote a yield increase substantial enough to cover the increased input cost. Achieving close to this rate is the key to maximising the return on the investment of an agronomic input.

reduced input costs

Does the optimum rate of an agronomic input differ between varieties that contrast for a corresponding characteristic? For example, would the optimum rate of a fungicide be consistently lower for a variety that is more resistant to Septoria than for a susceptible one? In order to answer these questions, trials are currently being conducted as part of the CIVYL project to evaluate whether the optimum rate of agronomic inputs for winter wheat and spring barley crops differs with varieties that contrast for characteristics that correspond to that input.

An example of one of these trials focuses on spring barley varieties with contrasting lodging resistance ratings grown under differing rates of nitrogen fertiliser. Nitrogen is essential to canopy formation and tiller production and, as such, increasing rates of nitrogen initially corresponds to increased yield and economic return.

However, excessive rates of nitrogen results in an increased risk of lodging and thus can cause large losses in economic return due to lost yield and wasted fertiliser. Therefore, if varieties are selected for good lodging resistance, this may allow for a higher optimum rate of nitrogen and a reduction in the potential losses due to lodged crops.

Despite this theory, preliminary results from trials conducted in 2014 did not indicate a significant difference in the optimum nitrogen rate between varieties differing in lodging resistance. However, repetitions of the trial are ongoing during the current growing season.

Furthermore, similar studies are ongoing investigating the potential of varieties of wheat and barley that contrast in lodging resistance, susceptibility to diseases, sprouting and grain quality to test whether rates of corresponding agronomic inputs can be adjusted.