Summary of Nitrogen Use and Uptake Efficiency and Crop Performance of Baby Spinach (Spinacia oleracea L.) and Lamb’s Lettuce (Valerianella locusta L.) Grown under Variable Sub-Optimal N Regimes Combined with Plant-Based Biostimulant Application
Biostimulant Effects on Spinach and Lettuce: Boosting Yield and Nitrogen Efficiency
Optimized nitrogen (N) fertilization can improve leafy vegetable growth and nutrient content. However, increasing crop performance requires higher Nitrogen Use Efficiency (NUE) to prevent environmental and health problems. Biostimulant effects on spinach and lettuce have shown promising results in supporting sustainable vegetable production.
Biostimulant Effects on Spinach and Lettuce Growth
This study tested a legume-derived plant hydrolysate (LDPH; Trainer®) applied as a foliar spray at 4 mL L−1, combined with different N fertilization levels (spinach: 0, 2.25, 4.5 g N m−2; lamb’s lettuce: 0, 2.5, 5.0 g N m−2). Spinach treated with LDPH showed yield increases of +16.8%, +14.2%, and +39.4% at N0%, N50%, and N100%, respectively. In lamb’s lettuce, N50% plants reached marketable yields similar to N100% plants when treated with LDPH.
Enhancing Biochemical and Physiological Traits
The biostimulant improved photosystem II activity (higher SPAD index) and increased chlorophyll levels (a, b, total). Leaf nitrate content also rose, which contributed to higher productivity.
Boosting Antioxidants and Nitrogen Efficiency
Additionally, LDPH enhanced antioxidant activities by +11.6% in spinach and +6.3% in lamb’s lettuce. Treated plants achieved better NUE and N-uptake efficiency: +17.8% and +18.8% for spinach, and +50% and +73.3% for lamb’s lettuce.
Overall, biostimulant effects on spinach and lettuce improve yield, quality, and N efficiency, making LDPH a valuable tool for sustainable greenhouse production.
Publication: Agronomy
