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.

中文翻译：

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草莓对冷藏和冰冻胁迫的生理生化响应及缓解因素的应用对策

背景：草莓通常种植在没有暖气的温室中或室外，在冬季，低温会遭受许多次破坏，有造成植物损失的危险。目的：探讨各种缓解剂抗寒和冰冻应激的功效。方法：对草莓植株进行各种缓解物质的叶面处理，例如甘氨酸甜菜碱，海藻糖，水杨酸和脯氨酸，然后暴露于5°C（冷藏处理）3周，然后暴露于– 10°C 3小时（冷冻处理） ，而对照植物则在20°C下生长。在每个时期结束时，测量叶片中的多胺和碳水化合物浓度，抗氧化酶活性，总酚和脯氨酸浓度，叶绿素浓度，脂质过氧化，电解质渗漏和H2O2产生。结果：与对照相比，所有施用的产品均减轻了低温胁迫，诱导了较低的电解质泄漏，但叶片中的蔗糖和果糖浓度更高。在冷冻温度下，水杨酸被证明是最有效的，这是基于观察到的最低的叶片损害，其次是海藻糖和脯氨酸。结论：基于叶片损伤评估，水杨酸是最佳的减缓剂，其诱导低的叶绿素a降解，低的超氧化物歧化酶，过氧化物酶和多酚氧化酶活性以及低的腐胺浓度。水杨酸被证明是最有效的，基于观察到的最低的叶片损害，其次是海藻糖和脯氨酸。结论：基于叶片损伤评估，水杨酸是最佳的减缓剂，其诱导低的叶绿素a降解，低的超氧化物歧化酶，过氧化物酶和多酚氧化酶活性以及低的腐胺浓度。水杨酸被证明是最有效的，因为观察到的叶片损伤最低，其次是海藻糖和脯氨酸。结论：基于叶片损伤评估，水杨酸是最佳的减缓剂，其诱导低的叶绿素a降解，低的超氧化物歧化酶，过氧化物酶和多酚氧化酶活性以及低的腐胺浓度。