October 28, 2021, by Lexi Earl

The effects of increasing night time temperatures on plants

It is vital to explore the night time processes of plants to protect our crops from changing climatic conditions, say Prof Erik Murchie and Dr Lorna McAusland

The last decade (2009-2019) was the warmest on record. With global temperatures predicted to increase between 2-5 °C over the next 30 years, and more frequent, longer lasting heatwaves, our crops are increasingly vulnerable to large, unpredictable reductions in yield. Rising temperatures are mostly associated with hotter days, but night time temperatures are increasing too – at a rate 1.4 times that of daytime temperatures. For every 1 °C increase in night time temperature there is an associated ~7% decrease in yield. The nocturnal processes of plants are less understood than daytime responses but we are beginning to understand their crucial role in crop productivity and resilience. It is therefore vital to explore night time processes in order to better protect crops and yields against rising temperatures.

Wheat is the world’s most widely grown crop, accounting for 30% of all cereals grown globally, and providing 20% of the global daily protein and carbohydrate uptake. The Murchie lab grows wheat under the simulated climatic conditions of North-Western Mexico, an area particularly vulnerable to high temperatures. Using state-of-the-art growth facilities with the ability to replicate field environments anywhere in the world using local weather station data, the Murchie lab can assess the response of wheat varieties to changing night time temperatures (in this case, those based on North-Western Mexico). The aim is to understand how plants cope with higher temperatures, and the genes that underpin that tolerance to heat.

The Murchie lab investigate nocturnal leaf-level processes, particularly focusing on the response of the stomata. Stomata are small pores found on the surface of leaves. These pores facilitate the exchange of water (transpiration) loss and carbon dioxide gain for photosynthesis. For a long time, these pores were believed to only open during the day. Since 1988, we have been aware that wheat open their stomata at night, losing water for no carbon gain. However, the role of nocturnal stomatal conductance (g_sn) is still a mystery.

Recently, we found g_sn varies between cultivars, and could play a role in growth or maintaining water uptake. During periods of high temperature and low water availability, high g_sn may be detrimental to wheat yields through decreasing available water. Conversely, high g_sn under well-watered conditions may have links with crop establishment and maintaining solute transport. This research is uncovering the elusive role of g_sn in wheat to determine whether g_sn plays a part in nocturnal heat tolerance.

Findings from the simulated growth lab will be compared with artificially warmed plots in the field in Mexico, so that complementary research on the same plants can be carried out at the same time on the other side of the world. Combining simulated growth facilities with field trials allows an understanding of the full impact of nocturnal warming – from leaf-level mechanisms all the way to determining the consequences on the yield.

Once we understand the genetic basis for nocturnal heat tolerance, findings can be applied to breeding programmes to improve wheat varieties. This will help stabilise or even improve wheat yields under increasing temperatures, an essential step for farmers to cope with climate change.

Further reading:

Noaa N. 2019. State of the climate: Global climate report for annual 2018. www.ncdc.noaa.gov/sotc/global/201813.

Perkins-Kirkpatrick S, and Lewis S. 2020. Increasing trends in regional heatwaves. Nature communications 11(1): 1-8.

Sadok W, and Jagadish SK. 2020. The hidden costs of night time warming on yields. Trends in plant science 25(7): 644-651.

Peng S, Huang J, Sheehy JE, Laza RC, Visperas RM, Zhong X, Centeno GS, Khush GS, and Cassman KG. 2004. Rice yields decline with higher night temperature from global warming. Proceedings of the N.A.S. 101(27): 9971-9975.

Shewry PR, and Hey SJ. 2015. The contribution of wheat to human diet and health. Food and Energy Security 4(3): 178-202.

Rawson H, and Clarke J. 1988. Nocturnal transpiration in wheat. Funct. Plant Bio. 15(3): 397-406.

Fricke W. 2019. Night-Time Transpiration–Favouring Growth? Trends in plant science 24(4): 311-317.

Publications:

McAusland L, Smith KE, Williams A, Molero G, and Murchie EH. 2021. Nocturnal stomatal conductance in wheat is growth stage specific and shows genotypic variation. New Phytologist.

Ferguson JN, McAusland L, Smith KE, Price AH, Wilson ZA, Murchie EH. 2020. Rapid temperature responses of photosystem II efficiency forecast genotypic variation in rice vegetative heat tolerance. The Plant Journal 104(3).

Erik Murchie is a Professor of Applied Plant Physiology, known for his work on crop physiology, investigating losses in photosynthesis and productivity caused by growth in suboptimal conditions.  He uses crop architecture, metabolic and photoprotectiveconstraints on photosynthesis and yield, collaborating to develop techniques for 3D analysis of crop structure and canopy modelling. He collaborates with those using traits and genes from diverse genetic backgrounds such as wild relatives of wheat and rice to try and regain properties that may have been lost during domestication and breeding, such resources will be useful for producing crops that can deal with future climates that are likely to be challenging.

Lorna McAusland is a post-doctoral BBSRC-Newton Fellow on the project ‘Exploiting night-time traits to improve wheat yield and WUE in the warming climate of North-western Mexico’. Lorna is a plant physiologist, specialising in photosynthetic processes and whole plant water regulation in response to abiotic stresses including temperature. While Lorna’s expertise focuses on the response of wheat and its wild relatives, she also has expertise over a wide selection of species including major crops (University of Nottingham and Essex), Tobacco (University of Illinois), Snapdragon (John Innes Centre) and Coriander (University of Nottingham).

Follow Erik and Lorna on Twitter: @ErikMurchie @Plantyperson

Read more about the equipment being used on this project

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