Pre-harvest melatonin applications improve post-harvest quality of tomato fruits

Tomato quality is shaped by both pre-harvest growing conditions and post-harvest factors; however, these aspects are often studied independently. This study explored the extent to which pre-harvest melatonin treatment affects tomato yield, quality and shelf life in terms of firmness, organoleptic properties (total sugar content and acidity) and bioactive constituents, with a focus on antioxidants (lycopene and vitamins C and E). Melatonin-treated plants were slightly more productive (7.8%) and yielded fruit with greater firmness (9.5%) at harvest. When stored at room temperature, tomatoes reddened earlier and stayed firm longer than the controls, while maintaining antioxidant vitamin levels. Under cold storage, pre-harvest melatonin treatment favourably affected total phenolic content (21.7%) and total antioxidant capacity (58.2%) for one week. Overall, pre-harvest melatonin improved tomato yield and quality, with effects lasting up to one week under both storage regimes. These findings position melatonin as a promising biostimulant to enhance post-harvest tomato quality. • Pre-harvest melatonin treatment improved tomato yield and quality at harvest. • Tomatoes reddened earlier and kept firm longer than controls at room temperature. • Total phenolic content and total antioxidant capacity were improved under cold storage. • Melatonin can be used as a biostimulant to improve crop yield and fruit quality.