Morpho-Physiological Responses and Secondary Metabolites Modulation by Preharvest Factors of Three Hydroponically Grown Genovese Basil Cultivars

Abstract

Sweet basil (Ocimum basilicum L.) is an economically important leafy vegetable especially in Mediterranean countries. In Italian gastronomy, the large elliptical leaves of the Genovese type are mostly used for the well-known pesto sauce, and almost all (>90%) professional production is for the food industry. The growing demand for fresh leaves with standardized technological and sensory characteristics has prompted basil producers to adopt advanced cultivation methods such as the floating raft system (FRS). The aim of this study was to evaluate the productive, qualitative, and physiological performance of three Genovese basil cultivars (“Aroma 2,” “Eleonora,” and “Italiano Classico”) in two successive harvests and at two densities (159 and 317 plants m–2). Caffeic, chicoric, rosmarinic, and ferulic acid were determined through the high-performance liquid chromatography (HPLC) system, whereas the extraction and quantification of the volatile organic compounds (VOCs) were performed by solid-phase microextraction (SPME) and gas chromatography coupled to a mass spectrometer (GC/MS). “Aroma 2” showed the highest fresh yield and photosynthetic rate together with the lowest nitrate content. For all the tested cultivars, the higher density, while reducing the number of leaves per plant, resulted in higher fresh and dry production per unit area, without altering the aroma profile. Successive harvests resulted in a significant increase in both the yield (37.5%) and the total phenolic acids (75.1%) and favored Eucalyptol and 1-octen-3-ol accumulation (+25.9 and +15.1%, respectively). The here presented comprehensive and multifactorial assessment of the productive and qualitative response of basil provides evidence of the positive effects (from biomass to specialized metabolites) that can be obtained from the management of the pre-harvest factors in soilless cultivation. In addition, it also highlights the role and constraints of the genetic factor in the observed response. We also discuss the implications of our work considering the impact for the food processing industry. Future research may explore the phenolic acids accumulation as a possible fortification means to extend the pesto sauce shelf life, reducing the need of added antioxidants and thermal processing.

Differential Response to NaCl Osmotic Stress in Sequentially Harvested Hydroponic Red and Green Basil and the Role of Calcium

“…In our work, high salinity levels (High Mix and High NaCl) reduced β-linalool, probably due to the depression of carbon assimilation required to produce VOCs, as inferred from the reduced DW ( Table 2 ). As is known in the literature, mutable conditions after the cut had a greater influence on the quality of the aroma profile ( Table 6 ; Zheljazkov et al, 2008 ; Corrado et al, 2020a ; Ciriello et al, 2021a , b ). Specifically, the two basil cultivars responded differentially to the successive cuts, with an increase in β-myrcene and β-ocimene and a reduction in eucalyptol observed in Green, while an increase in β-linalool was observed in Red.…”

“…The gas chromatography/mass spectrometry (GC/MS) analysis showed that the aroma profile of Red and Green basil was predominantly characterized by eucalyptol ( Table 6 ), in contrast to several studies in which β-linalool was the most abundant compound ( Marotti et al, 1996 ; Ciriello et al, 2021a , b ). This variation in the volatile composition may derive from the interaction of pre-harvest factors such as cultivar, environmental conditions, and cultural practices ( Farsaraei et al, 2020 ).…”

“…These secondary metabolites of aromatic herbs are a precious reservoir of bioactive molecules that the pharmaceutical industry could use to develop new drugs and improve their natural chemical diversity ( David et al, 2015 ). In this respect, recent scientific research has highlighted how genotype and agronomic practices, such as successive harvests, can be a valuable tool toward increasing the levels of desired secondary metabolites ( Nicoletto et al, 2013 ; Ciriello et al, 2021a , b ).…”

Nutrient Solution Deprivation as a Tool to Improve Hydroponics Sustainability: Yield, Physiological, and Qualitative Response of Lettuce

“…Among the different hydroponic techniques, the floating raft system (FRS) has become the most successful for producing leafy vegetables such as lettuce, basil, rocket, and radish [13,14]. Compared to conventional soil-based cultivation, FRS guarantees the (i) de-seasonalization of production, (ii) speeding up the growth cycle, (iii) increment of water use efficiency, (iv) reduction of labor costs, (v) increment of unit production through higher planting density, (vi) achievement of more stable and repeatable growth conditions, (vii) reduction of the incidence of telluric pathogens, and (viii) overcoming of the limiting conditions such as high salinity, heavy metal contamination, and suboptimal soil reactions (alkalinity and acidity) [5,8,[13][14][15]. FRS bestows a benefit for both consumers and fresh-cut vegetable growers who can produce residue-free soil products, which results in fewer washing procedures with less water waste [12,13].…”

Biostimulatory Action of Vegetal Protein Hydrolysate Compensates for Reduced Strength Nutrient Supply in a Floating Raft System by Enhancing Performance and Qualitative Features of “Genovese” Basil

“…Minor plant species, such as herbs, due to a heterogeneous and not fully explored reservoir of secondary metabolites, have rekindled the interest of both consumers and academics ( Kwon et al, 2020 ; Alexopoulos et al, 2021 ). Basil ( Ocimum basilicum L., Lamiaceae ) is an irreplaceable ingredient for traditional Italian dishes (“pesto” and pizza “Margherita”) and the pharma-cosmetic sector ( Barátová et al, 2015 ; Ciriello et al, 2021a , b ) due to the biosynthesis of low molecular weight organic compounds (i.e., monoterpenes and phenylpropanoids), responsible for its distinctive aroma ( Dias et al, 2016 ). On the other hand, the outstanding nutraceutical value of basil is mainly attributable to a heterogeneous phenolic profile (rosmarinic acid, chicoric acid, caffeic acid, and p-coumaric acid) that, like aroma, is strongly affected by the interaction between genotype and environment ( Jakovljević et al, 2019 ; Ciriello et al, 2021b ).…”