Based on the changing climatic conditions and the rapidly growing world population estimated to reach 9 billion by 2050, agro-food production systems face the challenge of needing to rapidly increase food production by at least 70% (Lo Piccolo and Landi, 2021; Ye et al., 2022). Furthermore, food security is becoming an alarming problem across the globe. To achieve the goals of higher yields and healthier food, the application of novel technologies such as the use of magnetized water treatment (MWT) represent a valuable approach to contribute to the sustainability of water resources (Alderfasi et al., 2016; Zúñiga et al., 2016; Esmaeilnezhad et al., 2017). The use of irrigation MWT is known to reduce the effects of salt concentration, increase yield, quality, and plant tolerance to biotic and abiotic stresses, and improve plant water use efficiency (WUE) in some crops (Maheshwari and Grewal, 2009; Hozayn et al., 2011; Hozayn et al., 2013; Hachicha et al., 2018; Akrimi et al., 2021). The first commercial magnetic device for water treatment was realized in 1958 by Vemeiren (1958), and current devices are environmentally friendly, competitively priced, and have no energy requirements (Ben Amor et al., 2017). The water is magnetized as it passes through a strong magnetic field (MF) that acts through two mechanisms: on the ions and molecules in the solution (ion mechanism), and on nuclei and particles already present in the solution (a surface mechanism) (Chibowski and Szcześ, 2018). The so-called “magnetic water” has been widely studied and adopted in industry, medicine, and agriculture (Surendran et al., 2016; Chibowski and Szcześ, 2018). MWT has a beneficial effect on common human conditions, such as atherosclerosis, arthritis pain, kidney and gall bladder stones, circulatory system normalization, aging, fatigue prevention, and weight control (Lee and Kang, 2013; Moosa et al., 2015; Raafat and Nabil, 2016; Ebrahim and Azab, 2017; Goyal et al., 2017). MWT also has beneficial effects on animals, helping them to live longer and healthier lives, with increased production (milk, wool, meat, eggs), growth performance, nutrient digestibility, and optimization of the rumen fermentation parameters (Gholizadeh et al., 2008; Sargolzehi et al., 2009; Ebrahim and Azab, 2017; El-Hanoun et al., 2017). The use of magnetically treated water in agriculture could be considered a sustainable method since it saves water consumption, and mitigates the harmful effects of drugs, toxins, and environmental pollutants by reducing methane production, which contributes to mitigating the environmental impact on livestock (Tyari et al., 2014; Sharma et al., 2018). The effects of a static magnetic field on seed germination, seedling development, and plant yield have been reported (Maffei, 2014; Chadapust et al., 2017; Nyakane et al., 2018; Abdollahi et al., 2019; Rifna et al., 2019). Factors such as polarity, intensity, exposure time, device magnet type, and the genotype-dependent effect can influence plant development positively or negatively (Surendran et al., 2016). On the contrary, irrigation MWT has resulted in a higher crop yield and soil properties even with low-quality water (Mohamed and Ebead, 2012; Ali et al., 2014; El-Kholy et al., 2015). The magnetic field influences the hydrogen bond-related properties of water in surface tension, evaporation rate, conductivity, salts solubility, pH, and molecular clustering of water, making it softer, lighter, and more easily absorbable by plants (Ospina-Salazar et al., 2018; Al-Bahrani, 2018; Wang et al., 2018; Pang, 2014; Alattar et al., 2020). However, although the effects on plant development have been investigated for at least half a century, the understanding of magnetic field action on water is still unclear. Positive impact on growth parameters (seed germination, shoot and root growth, emergence rate), soil (essential element uptake, mobility of nutrients from fertilizers, soil electrical conductivity, water holding capacity, soil pH), and water properties (water viscosity, surface tension, vaporization rate, water pH) were reported (Maheshwari and Grewal, 2009; Maffei, 2014). The beneficial effects of irrigation MWT on plant growth characteristics depend upon the species, the pathway length in the magnetic field, and the flow rate (Teixeira da Silva and Dobránszki, 2014; Surendran et al., 2016; Hachicha et al., 2018). The effect on seed germination and plant yield is reported in several species and is related to an increase in green and dry biomass, mobility, and micronutrient uptake (Fe, Zn, Mn), and higher photosynthetic activity due to greater total chlorophyll content compared to those irrigated with untreated water (Moussa, 2011; El-Sayed, 2014; Yusuf and Ogunlela, 2015; Haq et al., 2016; Shahin et al., 2016; Abd-Elrahman and Shalaby, 2017; Ospina-Salazar et al., 2018; Hozany and Qados 2010; Samarah et al., 2021). A previous study reported a significant effect on wheat and tomato seedling growth (Sestili et al., 2017). However, the MWT effect on plant metabolome is not yet widely studied. Based on this, we compared the effects of MWT and tap water on growth parameters and metabolomic profile of the seeds, roots, and epicotyls of durum wheat and lentil seedlings. This study aims to shed light on the differences in the level of metabolites involved in early plant development under this still controversial and seldom accepted technology.

Water properties before and after magnetization for both species are reported in Table 1 . The pH slightly decreased after the treatment in both species and timing except for lentil at t144. On the contrary, the levels of dry residue were higher in the treated water in durum wheat and lentil.

One of the priorities for agricultural research is to address the variations in plant growth environments caused by climatic changes that create adverse conditions that destabilize agricultural systems and endanger world food production (Anderson et al., 2020). Many studies have been conducted at species, organ, and tissue levels to understand the mechanisms of resistance, and the molecular and physiological responses that lead to greater tolerance to various abiotic stresses to preserve yield and quality of productions (Nakabayashi and Saito, 2015; Haak et al., 2017; Vives-Peris et al., 2020; Zhang et al., 2022). However, the evaluation of the possible use of novel technologies is still in progress (Okasha et al., 2022). In this regard, studies on the effect of magnetic fields (MF) on economically important plants have increased in the last decades. Many researchers reported the positive effect of MF on plant production and development, fruit quality, biotic stress resistance, water and nutrient uptake, and consequently higher WUE and NUE. On the contrary, the effects of using irrigation water treated with a magnetic field are poorly studied. In this work, the growth parameters and metabolite profile of durum wheat and lentil seedlings treated with magnetized water were investigated. The results showed that MWT significantly increased the plantlets development in both species, in agreement with previous investigations in other species in which the use of magnetized irrigation water promotes seed germination and plant growth even with low-quality water (Teixeira da Silva and Dobránszki (2014); El-Sayed, 2014; Elhindi et al., 2020; Akrimi et al., 2021; Liu et al., 2022; Okasha et al., 2022 and references therein). Magnetized treated water, also defined as “structured water”, has altered hydrogen bond structures that might directly or indirectly affect several physiological processes in plants leading to incremental growth and development (Nasher, 2008; Teixeira da Silva and Dobránszki 2014; Zúñiga et al., 2016; Lindinger, 2021). The pH of water slightly decreased with magnetization in both species during the treatment, in contrast with those reported by other authors who observed an increase in the pH value. This probably depends on the type of water used (tap, ground, lake, reservoir water) due to differences in mineral and organic material contents, and on the exposure to factors (light, heat, and mechanical disturbances) that could affect the magnitude, type, and stability of structuring (Chibowski and Szcześ, 2018; Lindinger, 2021). The lower pH of treated water is probably due to mainly fully protonated species in solution that can affect the mobility and availability of metal ions and thus the plant growth (Dai et al., 2014; Ponce et al., 2015). The treated water showed a higher dry residue with respect to the control tap water due to the higher frequency of collisions between ions on opposite sides, combining to form a mineral precipitate or insoluble compound (Gholizadeh et al., 2008). The MF water treatment led to a “memory effect” (or residual effect) that remains immediately after removing the MF and is based on the time and intensity of the treatment (Pang and Deng, 2008). For this reason, the influence of MWT continues after the treatment and along with plant development. The magnetization could regulate the uptake and translocation of mineral nutrients from the roots to the aboveground parts by affecting root morphology (Liu et al., 2022). Furthermore, in potatoes, tomatoes, and lentils, the MWT increased the diameter of aerial stem structure, indicating a possible cambium differentiation to xylem and phloem, and an improving photoassimilate translocation (Qados and Hozayn, 2010; Selim and El-Nady, 2011; Hozayn et al., 2016). In our study, the total root (principal and lateral roots) of both species treated with MWT showed a greater development than the control plants. Considering timings, the differences between treated and non-treated plants were more evident for lentil at the early stage (t1) but later in the growth of durum wheat (t3). This result is probably due to the differing root development and morphology of the two species; in durum wheat, the lateral roots were significantly influenced by MWT, while in lentil, only the principal root was affected by treatment (data not shown). The epicotyls of both species were not significant following treatment. In comparison to other works, our trials were conducted in a controlled environment and free-soil conditions to avoid any external influences. The use of plantlets has limited deeper investigation into the effect of MWT on plant development, since the last data were collected at a plant height of less than 100 cm. However, this also allowed us to highlight the metabolomic profile modifications that the plant undergoes at the early growth stage after treatment. In a previous study on wheat, durum wheat, and tomatoes grown on paper with sand treated with MW, we registered higher plant development (root and epicotyl) in wheat and tomatoes than in the controls (Sestili et al., 2017). Wheat and lentil were both used in previous studies on the influence of magnetized irrigation water on plant growth and under different stress conditions (Ćirković et al., 2017; Abd-Elrahman and Shalaby, 2017; Qados and Hozayn, 2010; Selim et al., 2019). In our work, we performed metabolomic analysis on seeds, roots, and epicotyls in both species at the same time points in which the growth parameters were collected to pinpoint a possible correlation between metabolome profile variation and plantlet development under the use of MWT. In our study, the metabolomic profile analysis of plants grown with MWT highlighted a significant increase for most of the metabolites in comparison to the use of tap water. Primary metabolites are directly involved in normal growth, development, and reproduction. Despite the increase in the concentration of the metabolites after using MWT, the correlation with root and epicotyl elongation was significantly different, highlighting that in both species, amino acids in roots and sugars in epicotyls are mainly positively affected by MWT, resulting in a higher or even “new” correlation with the growth parameters with respect to the control plantlets. The durum wheat epicotyl grown with MWT showed a positive correlation with oxalic acid and sugars with respect to controls. It is interesting to note that the oxalic acid content in durum wheat treated seeds was lower than the controls, indicating a positive effect of MWT since the consumption of foodstuffs rich in oxalic acid can induce serious health problems called hyperoxaluria that lead to kidney stones, bone disease, and anemia (Siener et al., 2006). The sugars positively correlated with epicotyl had different amounts; mannitol increased while sucrose decreased, indicating a dose dependent effect. El-Sayed reported that in broad bean treated with magnetic water, sugars increased because of the close relationship between stomatal conductance and photosynthesis (2014). Mannitol plays an important role in plant growth, photosynthesis, and abiotic stress tolerance by acting as an osmoprotectant (Claeys et al., 2014; Zulfiqar et al., 2020). Photosynthetic carbon converted to sucrose is vital for plant growth. Sucrose acts as a signaling molecule and a primary energy source that coordinates the source and sink development. The higher amount of some sugars was positively correlated with epicotyl, confirming the important role of mannitol in plant growth. In lentil, among the fatty acids, hexadecanoic acid and tetradecanoic acid were significantly influenced by MWT, but only tetradecanoic acid was positively correlated with root elongation. This confirms the role of saturated fatty acid in the biosynthesis and/or regulation of fundamental components for plant growth and seed development (Bonaventure et al., 2003). As far as we know, no other works have reported the effect of using MWT on plant metabolomic profiles. In other species, including wheat, a significant increase in photosynthetic pigment, total indole and phenol contents, antioxidant enzymes (SOD, CAT and APX) activity, and proline level in leaves was detected after using static MF (Rochalska, 2005; Hozayn and Qados 2010a; Hozayn and Qados 2010b; Dubois et al., 2013; Sadeghipour, 2015; Tehseen et al., 2016; Albys et al., 2018). The higher variation for both species observed in roots after treatment, could be associated with the mechanism that contributes to the osmotic adjustment since the root is a key organ involved in the uptake of water and nutrients, anchoring the plant to the substrate, and it is crucial for plant performance and crop productivity (Grossman and Rice, 2012; Mundim and Pringle, 2018). The great differences in sugars, amino acids, and polyols among organs, were previously reported in response to different stress conditions (Ullah et al., 2017; Borrelli et al., 2018; Skliros et al., 2018). The significant metabolite variation observed in durum wheat involved mainly sugar, while in lentil involved, other than sucrose, mainly organic acids, the stored pools of fixed carbon. This highlights the exclusivity of some compounds to the species studied and shows the first seedling development stage in both species can be significantly affected by the use of magnetized water and strictly related to morphological development. Selim et al. (2019) investigated the effect of irrigation with magnetized water in the leaves of two wheat cultivars under drought stress conditions, highlighting the best performances and significant increase of total soluble sugar concentration, total free amino acids, and proline after treatment. On the other hand, the results showed that the increase in the content of some metabolites is related to the use of magnetized water, as the consequence of the increased physical properties of water could affect the chemical and physical properties of polar metabolites. In general, the metabolites with osmoprotective functions significantly increased in almost all tissues and species analyzed, indicating a positive effect of using MWT, as MWT likely facilitates metabolite availability to act on their solubility. Among these metabolites, particular attention is reserved for threalose and mannitol in the root and epicotyl of durum wheat, and glycine and GABA in the seed and root of lentil, respectively. Moreover, Sadeghipour (2016) reported that magnetic water significantly improves WUE in some plants, especially those in regions where water resources are scarce, leading to an increase in plant development and crop productivity under reduced water input, which is of great importance for an arid environment suffering from frequent droughts (Selim and Selim, 2019; Liu et al., 2022). A deeper understanding of the effects of the MF on water and its influence on plant metabolism could revolutionize crop production under biotic and abiotic stress conditions, as well as water usage leading to crop yield improvement. However, since our study was done under controlled conditions, further investigations must be carried out that take into account the use of different genetic resources and must be repeated over time in open fields to evaluate the effect of the GE interaction. In addition to this preliminary study, other omics approaches could be used to gain a complete vision of the system biology and a deeper understanding of the metabolic mechanisms involved. A long-term cost/benefit study needs to be evaluated before the use of magnetized water can be considered a “green technology” accessible to all.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding author.

SS, CP conceived and designed the experiments. CP, DP, MAD collected the growth parameters. RB performed metabolomic analysis. SS, RB performed data statistical analysis, discussed the results, and wrote the manuscript. CP, DP carefully revised the manuscript. The authors read and approved the final manuscript.