Abstract
The study was arranged as factorial experiment in a completely randomized design with three applications of cultivar (Parus and Gaviota), 24- Epi brassinolide concentrations (0, 1 and 2 mgl-1) and temperature (normal and stress) as three replications. Some of the measuring characteristics showed that there was a significant difference among the treatments. Under heat stress conditions, foliar application of 24- Epi brassinolide at 1 mgl-1 concentration increased the amount of catalase and superoxide dismutase activity in leaves of Parus cultivar. Both cultivars fruits showed the highest total soluble solid contents in treatment 24- Epi brassinolide spraying at 2 mgl-1 concentrations under normal temperature. The highest total phenolics was in Gaviota cultivar treated with 24- Epi brassinolide spraying at 2 mgl-1 concentrations under normal temperature. Both cultivars had the lowest flavonoid in treatments without 24- Epi brassinolide and with 24- Epi brassinolide at 2 mgl-1 concentrations under heat stress conditions. In Gaviota cultivar, application of high concentration of 24- Epi brassinolide (2 mgl-1) prevented the reduction of total anthocyanin under heat stress conditions.
Highlights
Strawberry fruit has a great flavor and rich in vitamins which has a special place in the diet of people all over the world
The results of present study clearly demonstrated that 24- Epi brassinolide spraying had a significant effect on increasing of antioxidant enzymes activity in Parus and Gaviota cultivars and reducing of heat stress negative effects
In general it is thought that the heat damage caused to plants is due to the excessive production of active oxygen species, reduction of antioxidant enzyme activities and membrane damage.Reactive oxygen species are destroyed by antioxidant reported an elevated production of antioxidant enzymes by the application of 24- Epi brassinolide under high temperature stress.peroxidase has often served as a parameter of metabolism activity during growth alterations and environmental stress conditions(Gao et al, 2008)
Summary
Strawberry fruit has a great flavor and rich in vitamins which has a special place in the diet of people all over the world. Brassinosteroids are a group of plant hormones that regulate plant growth and development.24- Epi brassinolideis one of the most important forms of brassinosteroids. They control the growth of plants from seed germination to senescence (Kaplan and Gokbayrak., 2012). Antioxidant enzymes play the first line of defense against oxidative stress in plants. This has a significant impact on the concentration of O2 and H2O2in plants(Valizadeh et al, 2013). The present study aimed toselect optimal concentrations of 24- Epi brassinolide to improve some biochemical characteristics in strawberry cultivars under heat stress conditions
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