Alleviation of Chilling Injury in Postharvest Sweet Basil (Ocimum basilicum L.) with Silicon and Abscisic Acid Applications

Sweet basil (Ocimum basilicum L.) is highly susceptible to chilling injury (CI), resulting in the development of CI symptoms during cold storage that reduce postharvest quality and shelf life. This study evaluated whether silicon (Si) and abscisic acid (ABA) applications can mitigate these symptoms. In Trial 1, basil plants had a Si solution (189 mg/L Si from potassium silicate) or deionised water (control) applied during cultivation via rootzone irrigation or foliar spray. Some plants were also foliar sprayed with ABA (1000 mg/L) before harvest. In Trial 2, wollastonite was added to the growing media (0, 1, 2, 3, 4, 5 mL/L) as the Si source. Applying the Si solution using either method reduced leaf necrosis, fresh weight loss, and electrolyte leakage, extending shelf life to at least 14 days. There were also no negative impacts on plant performance during cultivation (chlorophyll content, shoot height, and canopy width). The ABA solution, alone or in combination with Si solution, reduced symptoms but less effectively, extending shelf life up to 8 days. Wollastonite had no positive effects. These findings suggest that Si solution applications are a promising strategy to alleviate CI during postharvest cold storage of basil at 3.5 °C.