Potato Review

22 POTATO REVIEW MAY/JUNE 2023 HEAT STRESS Samantha Brown, Technical Director at e Crop Smith Ltd, gives feedback on heat stress protection trials, and the 29% yield increases that were witnessed. Seaweed turns o the heat T HE increasing occurrence of extreme weather events poses a signi cant challenge to potato cultivation. Heat and drought stress reduces productivity, causes physiological defects in tubers, and damages crops. However, recent studies have shown that natural technologies containing plant hormones and betaines can mitigate or control potato plants’ response to heat stress. e Met O ce is predicting that 2023 will be hotter than 2022. In the UK, the top 10 warmest years since 1884 have occurred in the past two decades. e highest temperature ever recorded in the UK is 40.3C, set in Lincolnshire on July 19th last year. On the same day, 35C was exceeded for the rst time in Scotland. Whilst multiple records were broken in 2022, this year those are expected to be exceeded. Drought and heat stress are problematic in potato cultivation as modern varieties are adapted to grow at temperatures between 14C and 22C. Potato productivity is reduced at higher temperatures, typically whenever 25C is exceeded during the day. How heat a ects potato yields Potato plants under abiotic stress conditions su er a disturbance in normal hormonal regulation, plant metabolism and photosynthesis. Reactive oxygen species (ROS) are generated and these cause membrane damage and cell death. As a consequence, the rate of photosynthesis is reduced, the movement of assimilates from the leaves to the developing tubers is disrupted and biomass accumulation is compromised. e result is inhibition of tuberisation, secondary tuberisation, reduction in tuber bulking and ultimately loss of yield. In addition, heat stress causes physiological defects such as early skin set which is often followed by skin cracking and a loss of tuber quality. e earlier a heat wave occurs, and the longer it lasts, the more negative its impact. However, there are natural technologies that can minimise these losses to heat stress. Seaweed-based biostimulants High-quality seaweed extracts are rich sources of plant hormones, particularly auxins, cytokinins, and gibberellins, which play an important role in plants’ response to the environment. In addition to hormones, seaweed extracts are high in betaines, which are powerful osmoprotectants. ese enable plants to cope better with high temperatures and drought. Seaweeds contain much higher levels of plant hormones and betaines than land plants. A commonly-used seaweed species for extract production, Ascophyllum nodosum, has a concentration of betaines that is approximately 1.5-2.5% of dry weight, whereas land plants’ betaine concentration is typically less than 0.1% of dry weight. e high levels of plant hormones and betaines in seaweed extracts make them e ective tools for mitigating heat stress. By supplying plants with these compounds, seaweed extracts can regulate plant metabolism, reduce oxidative damage and improve plant growth and yield under stressful conditions. But, of course, the proof of the pudding is in the eating. 29.2% Yield increase in Solanum tuberosum ‘Melody’ as a result of CS1 application. Temperatures soared in summer 2022. A potato trial field carried out in 2022.