Seaweed Extract Increases Yield in Potatoes by 29%

Extreme weather events are becoming more commonplace. The use of seaweed extract minimises the damage caused by the worst of these extreme events – drought and heat stress.

In the UK the top 10 warmest years since 1884 have occurred in the last 2 decades.  The highest temperature ever recorded in the UK is 40.3°C, set in Lincolnshire on 19^th July last year, and on the same day 35°C was exceeded for the first time in Scotland.

Drought and heat stress are problematic in potato cultivation as modern varieties are adapted to grow at temperatures between 14⁰C and 22⁰C. Potato productivity is reduced at higher temperatures, typically whenever temperatures exceed 25⁰C during the day.

Fig.1. Extreme heat warnings were issued at multiple locations in July 2022.

Excess heat inhibits tuberisation, causes secondary tuberisation, decreases the rate of photosynthesis and inhibits biomass accumulation. In addition, heat stress increases physiological defects in tubers such as early skin set which is often followed by skin cracking and a loss of tuber quality. The earlier a heat wave occurs, and the longer it lasts, the more negative its impact.

Potato plants under abiotic stress conditions suffer a disturbance in normal hormonal regulation, plant metabolism and photosynthesis. Reactive oxygen species (ROS) are produced and these cause membrane damage and cell death. As a consequence the movement of assimilates from the leaves to the developing tubers is disrupted.

However, there are natural technologies which can minimise these losses to heat stress.

High quality seaweed extract is a natural, organic biostimulant which is high in antioxidants, vitamins and minerals which improve heat and drought tolerance by reducing the tissue damage caused by ROS. Foliar applications of seaweed extract directly counter the effects of abiotic stress as it contains a high level of betaine, which is a bioactive compound that plays an important role in osmoregulation.  In addition to betaine, seaweed extract is high in a range of phytohormones which have all been shown to play critical roles in the response of plants to heat stress.

But, of course, the proof of the pudding is in the eating….

2022 Lincolnshire Potato Trials

During 2022 independent, scientific trials were conducted in maincrop potato cv. ‘Melody’. The treatment consisted of a simple programme of an in-furrow application of a high-quality seaweed extract, CS1, followed by 6 low volume foliar sprays of the same product at regular intervals throughout the growing season.

During the 2022 growing season the UK experienced 3 heat waves, one in each month of June, July and August, which were crucial tuber formation and bulking periods for this crop. The impact of the prolonged heat stress was minimised in the treated plants and the results demonstrated a yield increase that was significant and considerable at 29.2%, equivalent to an extra 15 tonnes per hectare.

These results confirm that seaweed based biostimulants can reduce potato yield losses to abiotic stress. Instead of shutting down and going into protection mode, the potato plant is able to continue accumulating biomass despite heat stress conditions.

Fig. 2. 29.2% Yield increase in Solanum tuberosum ‘Melody’ as a result of CS1 seaweed extract application.

Excess heat is a devastating abiotic stress that causes substantial crop losses around the world. The frequency and magnitude of heat stress episodes are being intensified due to global climate change and we need to adapt. Understanding and implementing effective methods to mitigate abiotic stress is now a priority for farmers and growers across the UK.

Samantha Brown, Technical Director, The Crop Smith Ltd.