Appraisal of Combined Applications of Trichoderma virens and a Biopolymer-Based Biostimulant on Lettuce Agronomical, Physiological, and Qualitative Properties under Variable N Regimes

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.

Diplotaxis tenuifolia (L.) DC. Yield and Quality as Influenced by Cropping Season, Protein Hydrolysates, and Trichoderma Applications

“…The synthesis and accumulation of health-beneficial antioxidant compounds could be related to the enzymatic activity in processes involving phytochemical homeostasis and, as recorded in the present research, to the high tissue K and Mg content [6,62]. Consistently with our findings, the beneficial effects of organic nitrogen-based biostimulants on chlorophyll was also noted in baby lettuce [63]; most likely caused by amino acid abundance in PHs-treated plants, which augmented the chlorophyll pigment content and improved the net photosynthetic rate. Chlorophyll b is a component of the light-harvesting complex II (LHCII) and is crucial in dissipating excess energy [64].…”

Application of Trichoderma harzianum, 6-Pentyl-α-pyrone and Plant Biopolymer Formulations Modulate Plant Metabolism and Fruit Quality of Plum Tomatoes

“…Other plant beneficial microorganisms, in particular Trichoderma spp., are able to control pathogens and pests [ 7 , 8 ], as well as to increase plant nutrient use efficiency (NUE) [ 9 ], synchronize the up-regulation of photosynthetic capacity and carbohydrate metabolism [ 10 , 11 ], plus improve plant growth, yield and produce quality [ 12 , 13 , 14 ]. In particular, Trichoderma asperellum , Trichoderma atroviride , Trichoderma harzianum , Trichoderma virens and Trichoderma viride have been demonstrated to act as plant biostimulants, attributed to their capacity to stimulate NUE, and consequently increase plant vigor and tolerance to abiotic stresses [ 9 , 12 , 13 , 15 , 16 ]. It is important to specify that NUE does not only depend upon nutrient uptake by the plant, in particular of nitrogen, but it is also affected by the nutrient assimilation of organic compounds, as well as their translocation throughout the plant [ 17 , 18 ].…”

A Microbial-Based Biostimulant Enhances Sweet Pepper Performance by Metabolic Reprogramming of Phytohormone Profile and Secondary Metabolism

“…Other plant beneficial endophytic fungi include Trichoderma spp. Several of them are registered as microbial biological control agents (López-Bucio et al, 2015;Rouphael et al, 2020a). However, several studies reported that certain Trichoderma spp.…”