## 1 Introduction  
Light is a vital source for plant growth and development, driving key physiological processes such as photosynthesis, energy production, nutrient absorption, and the effective use of nutrients within plants [1]. Light quality influences the photosynthetic system, and enhancement of the quality light ratio (red:blue; R:B) significantly boosts the maximal chlorophyll a (Chl a) fluorescence of plants during both their light and dark adaptation [2]. An optimal combination of light (R:B) produces high biomass and metabolite production in plants [2]. In natural environments, plants adapt by using their light-sensing traits to distinguish between sunlight and dark, gray shade on the soil layer and green shade beneath the canopy [3]. Notably, light sensing enables plants to perceive environmental cues regarding the day's duration and time [4]. However, the high intensity of artificial light results in challenges for plants, and the physiological and molecular mechanisms that govern quality-light-mediated growth and nutrient acquisition in forage plants are largely unknown. Therefore, a fine-tuned strategy to improving the nutrient quality in alfalfa is highly desirable, and is a key target of this research. In this context, LEDs are frequently used to enhance plant growth and function. LEDs that emit narrow-band light influence various aspects of plant biology, including plants' seed germination, growth, photosynthesis, photosynthetic apparatus (PSA), and nutrition acquisition [2,3,5]. However, it is necessary to explore the research gaps on how light intensity and quality affect ROS signaling, antioxidant enzyme activity, associated gene expression, and mineral nutrition acquisitions in horticulture and other plant species. Blue light (BL), red light (RL), and far-red light (FRL) induce reactive oxygen species (ROS) generation in response to light intensity in several plant species. For instance, [PERSON] et al. found that BL and yellow light induce high levels of hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)), superoxide radicals (O\({}_{2}\)\({}^{\bullet-}\)), and malondialdehydehyde (MDA) in _Camptotheca acuminata_ compared to white light (WL) and RL [6]. In contrast, Chinese cabbage exhibited lower levels of H\({}_{2}\)O\({}_{2}\) in response to BL than in response to WL exposure [7]. Additionally, [PERSON] et al. found that RL significantly induces H\({}_{2}\)O\({}_{2}\) and programmed cell death (PCD), which are mediated by the redox-sensitive protein LSD1 and HY5 in _Arabidopsis_[8]. These studies suggest that ROS levels are differentially regulated in plants according to their received light intensity and quality. Improving plant growth, metabolite production, and ROS regulation through light quality is closely associated with the activation of key antioxidant enzymes in plants [9]. [PERSON] et al. found that red:blue (1:3) light increased the amounts of the enzymes MDHAR, DHAR, and GR in lettuce following 12 days of continuous light exposure (200 \(\upmu\)mol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\)), while the transcript levels of GMP, GME, GGP, GPP, GLDH, APX, MDHAR, DHAR, and GR were elevated after 3 days of light exposure [10]. The same study noted that the elevation of AsA pool-related enzymes is linked to the blue light intensity received by plants. However, the ratio of blue, red, or even FR is crucial for adjusting the ROS and antioxidant levels in plants. For instance, a low R:FR ratio increased the ROS and MDA levels even under control conditions in tomato plants, while a combined light treatment reduced ROS formation under salt stress [11]. In contrast, a low level of R:FR light reduced salt-induced cellular damage by increasing the activity and gene expression of the SOD, CAT, APX, and POD enzymes [12,13]. However, questions remain about how individual and/or combined exposure to red or blue regulates ROS signals, antioxidant enzyme activity, candidate gene expression, and nutrient acquisition in other crops like legumes or forage species.