Phytochemical Responses to Salt Stress in Red and Green Baby Leaf Lettuce (Lactuca sativa L.) Varieties Grown in a Floating Hydroponic Module

Abstract

Lettuce (Lactuca sativa L.) is one of the most popular leafy vegetables, appreciated globally as a low-calorie food with bioactive compounds. The application of a low dose of abiotic stress is considered a sustainable pre-harvest strategy to modify the nutraceutical value of horticultural products. In this work, we explored the response of two differently colored (red or green) baby leaf lettuce varieties to four NaCl concentrations in the nutrient solution (from 1 to 30 mM), using a full factorial design. We focused on leaf morphological parameters and possible phytochemical enhancement of the main polyphenols and anthocyanins, analyzed by LC-MS. The response to low-to-moderate salt stress exposure was affected mainly by salt concentration for leaf traits or by the cultivar for leaf color, with very limited factors’ interactions. Multivariate analysis indicated a predominant role of the genotypic factor in shaping differences in the two weeks growing cycle for baby leaf lettuce. Phytochemically, different dose–response models to sub-optimal saline conditions may be applied to the various compounds. A significant hormetic stimulation was present only for cyanidin-malonyl glucoside, the main anthocyanin present in the red cultivar.

Effects of NaCl and CaCl2 as Eustress Factors on Growth, Yield, and Mineral Composition of Hydroponically Grown Valerianella locusta

“…The physical properties of chloride are similar to nitrate, deeming their relation antagonistic since the nitrate transporter Z m NPF6.4, a transmembrane protein located in the root, is not able to discriminate between the two [ 99 ]. Since the reduction of nitrates in the leaf tissues was observed in the treatments with higher chloride concentration in the nutrient solution, our results could be associated with the antagonism of nitrate and chloride, rather than the osmotic potential of the nutrient solution itself, and are in agreement with the findings of other researchers [ 100 , 101 , 102 , 103 , 104 ].…”

Organic waste compost and spent mushroom compost as potential growing media components for the sustainable production of microgreens

“…Such results are likely due to the salinity stress caused by the high EC levels and the lower water holding capacity of the two SMC mixes (CC+SMC and PP+SMC). Several studies have shown a positive correlation or increase in DM content with salinity stress or increased EC levels (Ashbell and Evers, 2000;Ding et al, 2018;Corrado et al, 2021). Except for SMC-containing substrate mixes, all the other media tested provided microgreens with dry matter levels within the ranges considered typical for brassica and pea microgreens (Santos et al, 2014;Xiao et al, 2016;Di Gioia et al, 2017a;Di Gioia et al, 2019a).…”

Machine Learning for Plant Stress Modeling: A Perspective towards Hormesis Management

“…Being an adaptive response, the activation of plant metabolism also exhibits a hormetic behavior [ 87 , 88 , 89 ], and deliberately exposing crops to low-dose stress is a convenient means for stimulating metabolites accumulation [ 90 ]. Moreover, the metabolomics analysis of plant stress response along with bioinformatics makes it possible to find candidate markers for directing crop breeding and predicting crop performance under environmental stress [ 91 ].…”