Trichoderma spp. and Mulching Films Differentially Boost Qualitative and Quantitative Aspects of Greenhouse Lettuce under Diverse N Conditions
Department of Agricultural Science, University of Naples Federico II, 80055 Portici Naples, Italy
Council for Agricultural Research and Economics (CREA)-Research Center for Cereal and Industrial Crops, 81100 Caserta, Italy
Samagri Start up Innovativa srl, 84013 Cava de’ Tirreni, Italy
National Council of Research-IPSP, 80055 Portici Naples, Italy
Author to whom correspondence should be addressed.
Horticulturae 2020, 6(3), 55; https://doi.org/10.3390/horticulturae6030055
Received: 31 July 2020 / Revised: 29 August 2020 / Accepted: 2 September 2020 / Published: 4 September 2020
(This article belongs to the Special Issue Soil Science, Water and Nitrates Management in Horticultural Production)
The global increasing demand of lettuce is pushing farmers to boost their production through several technical means, including mulching and nitrogen fertilization. However, from an environmental protection perspective, the role of scientific research is to limit the excessive use of some chemical approaches. This research aims to evaluate the possible effects of two mulching films (black polyethylene, PE, and brown photoselective film, BF) and two treatments with a plant growth-promoting product, containing Trichoderma spp., (non-treated, - Control and treated with RYZO PEP UP, - TR), on the productive and qualitative traits of lettuce grown under four regimes of nitrogen (0, 30, 60 and 90 kg ha−1, N0, N30, N60, and N90, respectively). The marketable yield increased at higher nitrogen levels, but without differences between the N60 and N90 doses. The photoselective film elicited marketable yield, with an 8% increase over PE. N fertilization also improved photochemical efficiency (higher Soil Plant Analysis Development and chlorophyllous pigments biosynthesis), as well as antioxidant activities (lipophilic—LAA and hydrophilic—HAA) and bioactive compounds (phenols and total ascorbic acid—TAA). Interestingly, Trichoderma spp. had a positive effect on these qualitative parameters, especially when combined with mulching films, where the increase generated by PE-TR treatment over the all other treatments was 16.3% and 16.8% for LAA and HHA, respectively. In all treatments, the nitrate leaves content was consistently always within the legal limit imposed by the European community. Overall, although Trichoderma spp. did not engender a marked effect on yield, probably due to the short crop cycle, its positive effect on some quality traits is an interesting starting point for further research.