## 4 Results
### Additional Biochemical Traits Detected  
While the primary focus of this systematic review was the detection of chlorophyll, carotenoids, nitrogen, nitrate, and anthocyanins, several of the articles have identified additional biochemical traits in lettuce, basil, and spinach. These traits can provide deeper insights into plant physiology, nutrient content, and safety, offering promising opportunities for further research. Below, in Tables 15-25, findings are summarized. These biochemical traits hold an important role in plant physiology, quality, and nutritional value, and their detection with spectral measurements can help with optimizing plant growth, quality, and providing insight into plant health. * Glucose and sugar are energy storage and indicators of plant photosynthetic efficiency and are responsible for the sweetness and flavor profile of leafy greens [60]. Spectral measurements allow non-destructive quantification [37], which could improve understanding of metabolic processes and optimize quality traits in lettuce, basil, and spinach. * Phosphorus is an important micronutrient needed by plants in large quantities. It helps with energy transfer through ATP (adenosine triphosphate) and with the formation of nucleic acid and cell membranes. It is essential in various tasks, such as plant growth, root development, and photosynthesis [61]. Adequate phosphorus levels are needed for maintaining metabolic balance and optimizing yield [61]. A non-destructive monitoring can lead to more precise management of nutrient inputs, which would lead to more efficient application of fertilizers. By doing so, costs and environmental impacts can be reduced. * Potassium is a micronutrient that plays a role in regulating water balance in plants, activates enzymes, and has a significant role in photosynthesis [61]. It plays a crucial role in stomatal regulation, which helps plants efficiently control water loss and gas exchange; these processes are essential for maintaining plant hydration and nutrient transport. In leafy greens such as basil, lettuce, and spinach, potassium supports plant vigor, improves resistance to stress [61]. * Vitamin C (ascorbic acid) is a powerful antioxidant in plants; it is responsible for protecting them against oxidative stress that can be caused by excessive lighting, drought, and pollution [62]. By aiding in detoxification of reactive oxygen and maintaining cellular health, vitamin C is crucial for the plant defense mechanism [62; 63]. In leafy greens such as lettuce, spinach, and basil, ascorbic acid contributes to the overall well-being of the plant and enhances the nutritional quality [62]. For plant development, it helps with enzymatic processes and growth regulations [62]. * Water Content is essential to determine plant hydration and freshness. Water supports photosynthesis and transports nutrients throughout the plant [64]. Insufficient amounts of water can lead to wilting, weak plant health, and reduced growth [65]. Excessive water can affect root functions and make the plant more susceptible to diseases [66]. * Calcium is a plant nutrient required in cell wall structure and membranes, which gives tissue integrity and strength [67]. Adequate calcium levels prevent physiological disorders and improve the structural quality of leaves, ensuring durability and freshness [61]. Calcium also contributes to the general resilience of plant tissues, helping them withstand mechanical stress [61]. * Soluble solid content (SSC) refers to the concentration of dissolved solids in plant tissues, primarily sugars, organic acids, and other soluble compounds
* Magnesium is a key component of chlorophyll and a cofactor for many enzymatic reactions [61]. * Sulfur is pivotal for protein synthesis, enzyme activity, and chlorophyll production [61]. * Cadmium and Lead are heavy metals that pose significant risks to plant health and therefore to human consumption.