Evaluating the effect of 40% and 0% shading levels on the secondary metabolites, antifungal and anti-insect activities of extracts of Allium porrum cultivated hydroponically under greenhouse conditions

Abstract

Background: Allium species are generally reputed for their anti-pest properties; however, few studies have focused on optimising the quality and yield of anti-pest bioactive materials from these medicinal plants.Setting: Laboratory and greenhouse experiments were carried out on the Bellville campus of the Cape Peninsula University of Technology, Cape Town.Aims: This research study aimed to evaluate the effect of light intensity on the volatile constituents, antifungal and anti-insect activities of extracts obtained from Allium porrum L. cultivated hydroponically under greenhouse conditions.Methods: Seedlings of A. porrum were hydroponically grown under 40% shading and 0% shading conditions for 12 weeks. The phytochemical constituents of the aerial parts (leaf and bulb) of A. porrum were analysed. The antifungal activity against Fusarium oxysporum and the anti-insect activity on the grapevine mealybug (Planococcus ficus) was evaluated by microdilution and repellency bioassays, respectively.Results: Remarkably, the total polyphenol content was statistically higher (DF = 1, 6; F = 9.17; p 0.05) in plants exposed to 40% shade treatment. The gas chromatography-mass spectrometry (GC-MS) analysis revealed that the volatile compounds varied significantly (DF = 1; χ 2 = 3.435; p 0.05) between the two treatments. However, although a higher number of compounds (73) occurred in plants exposed to 40% shade than in those exposed to 0% shade (58), the shading effect on the number of compounds was not significant (DF = 1; χ 2 = 69.551; p 0.05). The acetone extracts of A. porrum that were cultivated under lower light irradiance showed a higher fungistatic activity against F. oxysporum in the antifungal bioassay.Conclusion: Broadly, this study revealed that lowering light intensity from 313 μmol m-2 s-1 to 153 μmol m-2 s-1 favoured a higher phenolic content, volatile constituents and higher anti-F. oxysporum activities in leeks.

Effects of Low-Light Environments on the Growth and Physiological and Biochemical Parameters of Indocalamus and Seasonal Variations in Leaf Active Substance Contents

“…This study found similar results: the TPC contents of 14 species of Indocalamus in different seasons ranged between 1.27 mg•g −1 and 5.41 mg•g −1 . Ntobela [54] demonstrated that low-light environments induced an increase in the contents of volatiles and phenolics, and Formisano [55] found that a low-light environment can promote the accumulation of total phenolic compounds. In this study, after the ST treatment, the annual average TPS contents of eight species of Indocalamus increased significantly compared to those under the CK treatment, with Jin, Dec, and Hir showing a lesser degree of decrease and only Kun, Bas, and Hun exhibiting significant decreases.…”

Comparing Crop Yield, Secondary Metabolite Contents, and Antifungal Activity of Extracts of Helichrysum odoratissimum Cultivated in Aquaponic, Hydroponic, and Field Systems

“…Some plant-based compounds have cosmetics and nutritional uses; they produce drugs, dyes, fragrances, and dietary supplements [ 18 ]. Plant pathogens and predatory insects have been successfully controlled using plant extracts with high bioactive secondary metabolite contents [ 19 , 20 , 21 ]. Therefore, developing cultivation protocols to optimize the secondary metabolite content, and thus, the medicinal value of plants, is certainly a worthy research venture.…”