Combined Selenium and Iodine Application Modulates Antioxidant and Photosynthetic Responses in Raspberry Seedlings...

Area of Science:

• Plant Physiology
• Agricultural Science
• Environmental Stress Biology

Background:

• Heat stress significantly limits raspberry cultivation in tropical and subtropical regions.
• Effective strategies for mitigating heat stress in raspberry seedlings are limited.
• Selenium (Se) and iodine (I) are known to individually enhance plant abiotic stress tolerance.

Purpose of the Study:

• To investigate the complementary effects of combined selenium and iodine foliar application on heat-stressed raspberry seedlings.
• To evaluate the physiological, biochemical, and photosynthetic responses of 'Heritage' raspberry seedlings to Se and I under high-temperature conditions.
• To explore the potential of Se and I co-application as a strategy for improving heat stress acclimation in raspberries.

Main Methods:

• Raspberry seedlings ('Heritage') were subjected to foliar application of various combinations of selenium (0, 25, 50 mg L⁻¹) and iodine (0, 50, 100 mg L⁻¹).
• Seedlings were exposed to controlled heat stress conditions (40/18 °C day/night) for three days.
• Physiological, biochemical, antioxidant, and chlorophyll fluorescence parameters were assessed during and after the stress period, with Principal Component Analysis used for data interpretation.

Main Results:

• Intermediate Se and I combinations helped maintain plant water status and photosynthetic performance during heat stress.
• Post-stress, these treatments facilitated osmotic adjustment and enhanced antioxidant regulation, aiding seedling recovery.
• Principal Component Analysis confirmed the link between intermediate Se and I levels and improved antioxidant regulation, osmotic adjustment, and photoprotection.

Conclusions:

• Co-application of selenium and iodine triggers complementary physiological mechanisms for heat-stress acclimation in raspberry seedlings.
• This combined approach offers a promising strategy for enhancing raspberry seedling tolerance to high-temperature stress.
• Optimized Se and I application can improve raspberry cultivation viability in challenging tropical and subtropical environments.