Appraisal of Combined Applications of Trichoderma virens and a Biopolymer-Based Biostimulant on Lettuce Agronomical, Physiological, and Qualitative Properties under Variable N Regimes
Youssef Rouphael, Petronia Carillo, Giuseppe Colla, Nunzio Fiorentino, Leo Sabatino, Christophe El‐Nakhel, Maria Giordano, Antonio Pannico, Valerio Cirillo, Edris Shabani, Eugenio Cozzolino, Nadia Lombardi, Mauro Napolitano, Sheridan L. Woo
Abstract
The current research elucidated the agronomical, physiological, qualitative characteristics and mineral composition of lettuce (Lactuca sativa L. var. longifolia) after treatments with a beneficial fungus Trichoderma virens (TG41) alone or in combination with a vegetal biopolymer-based biostimulant (VBP; ‘Quik-link’). The experiment consisted of lettuce plants grown in three N conditions: sub-optimal (0N kg ha−1), optimal (70N kg ha−1), and supra-optimal (140N kg ha−1) N levels. Lettuce grown under 0N fertilization showed a significant increase in fresh yield when inoculated with TG41 alone (45%) and a greater increase with TG41 + VBP biostimulant (67%). At 48 days after transplanting, both the TG41 alone or TG41+VBP biostimulant induced higher values of CO2 assimilation in comparison to the control. The mineral concentrations in leaf tissues were greater by 10% for K and 12% for Mg with the TG41+VBP treatments compared to the untreated lettuce. The lettuce plants receiving either TG41 alone or TG41+VBP biostimulants had a significantly lower nitrate content than any of the untreated controls. In non-fertilized conditions, plants treated with TG41+VBP biostimulants produced lettuce of higher premium quality as indicated by the higher antioxidant activity, total ascorbic acid (+61%–91%), total phenols (+14%) and lower nitrate content when compared to the untreated lettuce.