Sodium Silicate Reduces Postharvest Decay on Hami Melons: Induced Resistance and Fungistatic Effects

Area of Science:

• Plant Pathology
• Agricultural Chemistry
• Biochemistry

Background:

• Postharvest decay significantly impacts Hami melon quality and shelf-life.
• Fungal pathogens like Alternaria alternata, Fusarium semitectum, and Trichothecium roseum cause substantial economic losses.
• Developing effective and safe control strategies for fruit decay is crucial for the horticultural industry.

Purpose of the Study:

• To evaluate the efficacy of sodium silicate (Si) in controlling decay in Hami melons.
• To investigate the optimal concentration of Si for disease control without causing phytotoxicity.
• To elucidate the role of Si in inducing plant defense mechanisms against fungal pathogens.

Main Methods:

• In vitro assessment of Si's effect on mycelial growth of key fungal pathogens.
• Application of varying Si concentrations (25, 50, 100, 200 mM) to Hami melon fruit.
• Pre- and post-inoculation application timing of Si treatments against Trichothecium roseum.
• Measurement of decay incidence and severity.
• Enzyme assays for peroxidase and chitinase activity in Si-treated fruit.

Main Results:

• Sodium silicate significantly inhibited the in vitro growth of Alternaria alternata, Fusarium semitectum, and Trichothecium roseum.
• 100 mM Si was the most effective concentration for disease control, while 200 mM proved phytotoxic.
• Pre-inoculation Si application at 100 mM resulted in lower decay incidence and severity compared to post-inoculation.
• Si treatment induced the accumulation of defense-related enzymes, peroxidase and chitinase, in Hami melon fruit challenged by T. roseum.
• Induced enzyme activity was sustained for at least 9-10 days at room temperature.

Conclusions:

• Sodium silicate is a promising agent for controlling postharvest decay in Hami melons.
• The protective effect of Si is mediated by the induction of plant defense responses, specifically enhanced peroxidase and chitinase activity.
• Optimal application of sodium silicate can enhance the shelf-life and quality of Hami melons by mitigating fungal diseases.