Exploring the impact of drought on 2017 wheat crop

By Professor Donal O’Sullivan, Professor of Crop Science in the School of Agriculture, University of Reading

Unfavourable weather patterns and their impact on crop production have again been a major talking point in farming circles. Bizarrely, whilst the total amount of rainfall in 2017 to date is very close to the historic average, it has been distributed in a very unhelpful way (as data from the University’s Meteorology Department weather station helpfully plotted out in an up-to-the-minute annual graph shows).

Weather data from the University of Reading shows the drought in April and summer deluge

First and foremost, there was almost no meaningful rainfall for a six-week period spanning the calendar month of April, when crops were going through their most rapid phase of growth. But to compound matters, there was an unusual deluge in the second half of July, when dry conditions would have been more conducive to straightforward ripening and harvest.

Assessing the impact of this latest extreme weather episode was the subject of a BBC South Today news piece I contributed to on Tuesday evening. The research team I am leading in the School of Agriculture, Policy and Development may have some answers. We designed a large field experiment designed both to quantify yield losses due to drought and to detect varieties with drought-beating characteristics.

To do this, we made side-by-side comparisons of growth and yield of 400 wheat varieties under natural field conditions and natural conditions with supplementary irrigation. Using a combination of ground and drone-based monitoring technologies, we captured a comprehensive picture of the responses of each individual variety over time to these contrasting growing conditions to highlight the impact of these weather events.

The results were stark. Our preliminary yield results from control plots indicate that this year’s drought caused a 28% loss of potential yield. If losses at this level were observed across the 2 million hectares of UK wheat crop, we are talking about potentially 7-8 millions of tonnes of lost yield, making how to beat this magnitude of drought a billion-dollar question.

Samer Amer, a member of the Reading research team, oversees a drone flight above the trial wheat field

Importantly, the research is not just quantifying the potential loss, but pointing the way forward in terms of making the best of variable rainfall patterns. A number of the varieties were doing unexpectedly well on the block grown in natural conditions with no added water.

The common genetic characteristics of these varieties hold the key to traits such as deep-rooting that could be used to access deep water reserves unavailable to varieties with a very similar appearance above ground.

This research will inform future breeding of more resilient crop varieties, going some way to insuring the UK wheat crop against climate change. Now, we just need a break in the weather to complete the 2017 harvest.

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  1. Brett Townsend’s avatar

    A wild card enquiry that I hope you may be able to direct me to a possible solution…
    We own a listed thatched house in Dorset and are having one side rethatched. The thatcher had to replace the poles / branches that support the roof so had to go deep into removal of the 8 layers of thatch (about 4 feet in). I am wondering if the wheat straw from the bottom layer can be used to give us a date for the cottage as the thatcher thought that part of the roof was 17th century. The ears(?) of the old straw are still present and are much smaller than modern ears.

    Can you offer any ideas, please?

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  2. Donal O'Sullivan’s avatar

    Dear Brett,

    The smaller ears found 4-ft deep in a c.17 thatched roof cottage is likely to be emmer wheat.

    I don’t know if the ear itself can be dated, it could at least be identified. The sample may be of interest to researchers working in the area of bioarcheaology. Try Martin Jones at the MacDonald Institute in Cambridge for example.

    Hope this helps,
    Donal

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