High-temperature affects morphological, physiological, and biochemical traits in day-neutral strawberries

Abstract High-temperatures significantly constrain the growth and resilience of day-neutral strawberry ( Fragaria × ananassa ) varieties, affecting their morphological, physiological, and biochemical characteristics. In this study, frigo plants of six day-neutral strawberry cultivars (Albion, Monterey, Portola, Redlands Hope, San Andreas, and Sweet Ann) were initially grown for 5 weeks in 15 cm diameter plastic pots (3:1:1; garden soil, peat, perlite) under open conditions. After 2–3 weeks of acclimatization at 23/15 °C (day/night) in a climate chamber, the temperature in one chamber was maintained at 23/15 °C, while the other was subjected to high-temperature conditions at 30/25 °C. Temperature and cultivars significantly influenced most of the morphological, physiological, and biochemical characteristics of strawberries. High- temperature caused a significant decrease in root length, number of leaves, leaf area, leaf fresh and dry weight, root fresh and dry weight, plant fresh and dry weight, and membrane stability index, while increasing leaf surface temperature, Malondialdehyde content, starch content, sugar content, and total carbohydrate content of strawberry plants, indicating enhanced oxidative stress and metabolic reprogramming. Among varieties, the highest values of the number of leaves, leaf area, leaf fresh and dry weight, root fresh weight, and plant fresh and dry weight were recorded in the San Andreas variety. The Portola variety exhibited considerably higher values of root length and root dry weight. The leaf surface temperature was higher in Monterey, and the membrane stability index was higher in San Andreas. The highest values of MDA and sugar content were observed in the Albion strawberry variety, and the highest values of starch and total carbohydrate content were observed in Monterey. The findings highlight the detrimental effects of high-temperatures on day-neutral strawberry varieties and emphasize the importance of selecting heat-tolerant cultivars for sustainable strawberry production under changing climatic conditions.