Abstract
In the present study, the effect of biostimulants application on the nutritional quality and bioactive properties of spinach cultivated in protected environment under water stress conditions was evaluated. For this purpose, four commercially available biostimulant products (Megafol (MEG), Aminovert (AM), Veramin Ca (V), Twin Antistress (TA), and two spinach genotypes (Fuji F1 and Viroflay) were tested under two irrigation regimes (normal irrigation (W+), and water-holding (W–). Fat and carbohydrates content was favored by water stress when Megafol (MEGW+) and Veramin (VW+) were applied on Fuji plants, while calorific value was also increased by MEGW+ treatment. In contrast, protein and ash content increased when AMW– and TAW+ were applied on Viroflay plants. Raffinose and glucose were the most abundant sugars, followed by sucrose and fructose, with the highest contents recorded for Fuji plants when AMW+ (fructose, glucose and total carbohydrates), CW– (sucrose), and TAW– (raffinose) treatments were applied. Regarding organic acids, oxalic and malic acid which had the highest contents for the TAW– (Viroflay plants) and AMW– (Fuji plants) treatments, respectively. α- and γ-tocopherol were the only isoforms detected with MEGW– and VW– inducing the biosynthesis of α-tocopherol, while AMW+ increased γ-tocopherol content in Fuji plants. The main fatty acids were α-linolenic and linoleic acids which were detected in the highest amounts in AMW–, AMW+, and TAW+ the former and in AMW–, VW–, and CW+ the latter. Regarding phenolic compounds content, peak 12 (5,3′,4′-Trihydroxy-3-methoxy-6:7-methylenedioxyflavone-4′-glucuronide) was the most abundant compound, especially in Viroflay plants under normal irrigation and no biostimulants added (CW–). The antioxidant and cytotoxic activity of the tested samples did not show promising results when compared with the positive controls, while a variable antibacterial activity was recorded depending on the tested biostimulant, irrigation regime and genotype. In conclusion, a variable effect of the tested biostimulants and irrigation regimes was observed on bioactive properties and chemical composition of both spinach genotypes which highlights the need for further research in order to make profound conclusions regarding the positive effects of biostimulants under water stress conditions.
Highlights
Global warming and the prolonged dry periods along with the untimely weather conditions due to the climate change (CC) have raised the scientific research and multiple studies have been carried out to understand, explain and prevent their detrimental side effects on living organisms and the environment [1,2,3]
Water stress increased ash content and induced the biosynthesis of glucose and ascorbic acid, whereas normally irrigated plants were richer in carbohydrates, sucrose, raffinose, malic acid, α- and total tocopherols
The same treatments reduced the oxalic acid content which is considered as an antinutritional factor, while αand total tocopherols increased by the application of Megafol and Veramin Ca
Summary
Global warming and the prolonged dry periods along with the untimely weather conditions due to the climate change (CC) have raised the scientific research and multiple studies have been carried out to understand, explain and prevent their detrimental side effects on living organisms and the environment [1,2,3]. Plant biostimulants could be considered as those compounds that may promote plant growth, increase tolerance to abiotic stressors and at the same time improve natural resources use efficiency [6,11,12] In this context, various natural compounds could be included in this group such as beneficial microorganisms, protein hydrolysates, humic acids, seaweed extracts, and amino acids [13,14,15,16]. The aim of the present was to study the effect of four biostimulants application on the chemical composition and bioactive properties of spinach plants grown under water stress conditions For this purpose, two commercially available spinach genotypes were selected and grown in soil under protected conditions and controlled irrigation regimes to evaluate the potential of using biostimulants as an environmental friendly cultivation strategy to alleviate the negative effects of water stress conditions and to improve the quality of vegetable crops. Considering the varied composition of the applied biostimulants possible differences in plant response attributed to such variation will be discussed
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