Strawberry physiological and biochemical responses to chilling and freezing stress and application of alleviating factors as countermeasures

Abstract

BACKGROUND: Strawberry is usually cultivated in unheated glasshouses or outdoors, suffering many times by low temperatures during the winter period, with the danger of plant losses. OBJECTIVE: To investigate the efficacy of various alleviating agents against chilling and freezing stress. METHODS: Strawberry plants were foliarly treated with various alleviating substances, i.e. glycine betaine, trehalose, salicylic acid and proline and exposed to 5 °C (chilling treatment) for three weeks followed by a three hour exposure to – 10 °C (freezing treatment), while control plants were growing under 20 °C. At the end of each period polyamine and carbohydrate concentration, antioxidant enzymes activities, total phenols and proline concentration, chlorophyll concentration, lipid peroxidation, electrolyte leakage and H2O2 production in the leaves were measured. RESULTS: All applied products alleviated chilling stress, inducing lower electrolyte leakage, but higher sucrose and fructose concentration in the leaves compared to control. Under freezing temperature, salicylic acid proved to be the most efficient based on the lowest leaf damage observed, followed by trehalose and proline. CONCLUSIONS: Salicylic acid was the best alleviation agent based on leaf damage evaluation, by inducing low chlorophyll a degradation, low superoxide dismoutase, peroxidase and polyphenol oxidase activities as well as low putrescine concentration.

Mitigation of High Solar Irradiance and Heat Stress in Kiwifruit during Summer via the Use of Alleviating Products with Different Modes of Action—Part 1 Effects on Leaf Physiology and Biochemistry

“…The concentration of the total phenols, total o-diphenols, total flavanols, and total flavonoids was determined in the supernatants, according to Roussos et al [24]. The results expressed as mg equivalent gallic acid (GAE), caffeic acid (CAE), catechin (CtE), and CAE per g fresh weight (FW), respectively.…”

“…The antioxidant capacity was determined based on the DPPH (2,2-diphenyl-1-picryl hydrazyl), FRAP (Ferric Reducing Antioxidant Power), and ABTS assays, as described by Roussos et al [24] and Re et al [25], and are expressed in µmol Trolox equivalents (TE) per g fresh weight.…”

“…The soluble sugars were determined using 100 mg of dry leaf powder which was extracted twice with 4 mL of HPLC-grade water based on a microwave-assisted extraction method, as has been described by Roussos et al [24]. Sugars were detected and quantified by HPLC using a Waters 510 isocratic pump (Waters, Milford, MA, USA) delivering acetonitrile: water (80:20), as the mobile phase at a flow rate of 1.0 mL min −1 to an Adamas Amino 5µ column (250 × 4.6 mm) (Sepachrom, Italy), working at 35 • C. A refractive index detector (Hewlett Packard HP1047A) (Agilent, CA, USA) was used for the determination of the four soluble sugars in the kiwifruit leaves, i.e., sucrose, glucose, inositol, and fructose.…”

Chlorophyll Fluorescence Imaging for Early Detection of Drought and Heat Stress in Strawberry Plants

“…Strawberry ( Fragaria × ananassa ) is a crop with significant socioeconomic value worldwide, owing to its organoleptic properties and high nutritional value, as it contains vitamins, minerals, and bioactive compounds such as antioxidants [ 1 ]. Therefore, the consumption of strawberries, either fresh or processed, continues to significantly increase, with the market surging every year [ 2 , 3 , 4 , 5 ]. Strawberry is one of the most widely grown crops in South Korea, which is a major strawberry-producing country alongside Poland, Mexico, Egypt, Turkey, Spain, and the United States [ 6 , 7 ].…”