Biostimulation of Hydroponic Lettuce With Milk‐Derived Protein Hydrolysate Under Seasonal Nutrient Limitation: Enhancement of Physicochemical and Flavor Attributes

Summary

Protein hydrolysates (PHs), including milk‐derived PH (MPH), are sustainable biostimulants that can enhance crop yield, quality, and stress tolerance in hydroponic systems while reducing chemical fertilizer dependance. The MPH tested was produced by acid hydrolysis, giving a high degree of hydrolysis and a profile dominated by free amino acids, principally glutamic acid, aspartic acid, proline, leucine, and valine, with organically bound nitrogen and minerals. Cos lettuce ( Lactuca sativa L.) was grown across cool, summer, and rainy seasons under a half‐strength control (HS), HS with 1 mL L −1 MPH (HS + MPH1), and full‐strength with 1 mL L −1 MPH (FS + MPH1). HS + MPH1 increased fresh yield over HS in all seasons (+13% cool, +25% summer, +46% rainy); the largest relative gain occurred in t