12 May 2022
Samantha Brown, Technical Director at The Crop Smith Ltd looks at how a natural resource can help counteract heat stress and drought.
Here in the UK we are heading towards the hottest part of the year and crop growth is well under way. However, the seasons are no longer as predictable as they once were, with extreme weather events becoming more commonplace. The use of seaweed extracts is proving to help minimise the damage caused by the worst of these extreme events – drought and heat stress.
According to the World Health Organisation an estimated 55 million people globally are affected by droughts every year and they are the most serious hazard to livestock and crops in nearly every part of the world. Here in the UK, projections show a trend towards drier summers on average, with stronger droughts forecast for southern parts of the UK.
Drought stress causes a drop in crop productivity by impeding nutrient uptake and interfering with water relations. Photosynthesis and the accumulation of biomass are also negatively affected. Plants under drought conditions produce reactive oxygen species (ROS) which cause membrane damage and cell death. A good quality seaweed extract is high in antioxidants and will improve drought tolerance by reducing the tissue damage caused by ROS. In addition, seaweed extract foliar sprays advance early establishment and rooting, improving the plant’s ability to access available water.
The top 10 warmest years for the UK since 1884 have occurred since 2002 and the highest temperature ever recorded in the UK is currently 38.7 °C, set in Cambridge in July 2019.
Photosynthesis is one of the most heat sensitive physiological processes in plants and high temperature has a more damaging effect on the photosynthetic capacity of C3 plants such as potatoes, wheat, rye, oats, and barley than it does on C4 plants such as maize.
In temperate regions such as ours, high temperature shocks during the reproductive phase in crop growth can cause substantial reduction in the yield of cereals and oilseed crops. The quality of the final produce is also impacted by heat stress as it significantly reduces oil, starch, and protein content. In addition, a decline in grain weight and total number of grains can occur.
Foliar applications of high quality seaweed extracts directly counter the effects of heat stress as they contain osmo-protectants like betaine, and phytohormones such as auxin, which co-ordinate plants’ response to heat.
As we move forward with climate change, understanding and implementing effective methods to mitigate abiotic stress will become a priority for farmers and growers across the UK. Seaweed extracts are an essential part of the toolkit keeping farming businesses profitable into the future.