Increased nutrient solution concentration during early fruit development stages enhances pungency and phenylalanine ammonia-lyase activity in hot chili (capsicum annuum l.)

Summary

This field trial examined how increasing nutrient solution concentration at different fruit development stages affects pungency and enzyme activity in hot chilli cv. 'Super hot'. Whilst increased nutrient concentration did not significantly influence fruit characteristics or yield, plants receiving elevated nutrient concentration (EC 3.6 mS cm⁻¹) during weeks 1-2 after first bloom showed significantly higher capsaicinoid contents and peak phenylalanine ammonia-lyase activity, suggesting a critical developmental window for nutrient manipulation to enhance pungency.

Regional applicability

This study was conducted in Thailand under controlled net-house conditions with specific tropical cultivars and coconut-coir substrate. Findings may have limited direct transferability to United Kingdom outdoor or glasshouse chilli production systems, which operate under different climate, growing seasons and substrate conditions; however, the timing principle for nutrient enhancement during early fruit development warrants investigation under UK growing conditions.

Key measures

Electrical conductivity (EC) of nutrient solution (mS cm⁻¹); oleoresin, capsaicin, dihydrocapsaicin and capsaicinoid contents; phenylalanine ammonia-lyase activity (mmole mg⁻¹ protein); fruit characteristics and yield

Outcomes reported

The study measured yield, pungency (oleoresin, capsaicin, dihydrocapsaicin and capsaicinoid contents), and phenylalanine ammonia-lyase (PAL) enzyme activity in hot chilli fruits across different nutrient concentration treatments applied at various fruit development stages.

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