Capsicum is one of the most economically important genera in the Solanaceae family. Capsicum fruits (peppers) are rich in phytochemicals with high nutritional value and significant health-promoting characteristics. The phytochemical profile of peppers consists of capsaicinoids, carotenoids, and phenolics, primarily. Currently, most of the pepper production is carried out under protected horticulture conditions. The objective of this article was to provide a comprehensive review on how light characteristics and manipulation by different horticultural technologies can affect the biosynthesis and accumulation of phytochemicals in Capsicum fruits. The use of shade nets or plastic covers to reduce light intensity does not seem to yield consistent responses on the phytochemical profile, as the final profile results from the interaction of several factors. Other factors involved in the accumulation of phytochemicals include temperature, water availability and plant nutrition. Exposure of plants to supplemental light with specific wavelengths (using LEDs) seems to result in a more precise stimulation of specific metabolites. In this article, we examine the effects of light irradiance and spectrum on the specific phytochemicals of Capsicum fruits.

Piquin pepper fruits, a semi-domesticated wild pepper species highly valued in Mexico, currently face the threat of unsustainable harvesting practices that endanger the species. For this reason, it is necessary to establish sustainable agricultural practices for the cultivation of these peppers. Solar radiation, a critical determinant in crop production, plays a crucial role in plant development, influencing a spectrum of physiological and morphological processes, including the synthesis of phytochemicals. Our study evaluated the effect of light manipulation through colored shading nets on the phytochemical profile, antioxidant capacity, and fruit quality of semi-domesticated piquin peppers at two maturation stages: immature and mature (green and red fruits). Our hypothesis posits that these shading treatments may induce changes in these fruits’ phytochemical composition and antioxidant properties, as well as quality. Our results indicate that the shading treatments and maturity stage have significant on capsaicinoid and carotenoid levels, with the highest levels observed in mature fruits. Notably, red fruits grown under black shading treatments resulted in the highest capsaicinoid levels. Carotenoid levels were higher in the black shading treatment during the first cycle, while in the second cycle, the blue shading treatment showed elevated carotenoid levels, suggesting that high irradiance conditions could reduce carotenoid contents. Although no significant differences were observed among the treatments in green fruits, in red fruits, both black and blue treatments exhibited the highest total phenolic compounds in both production cycles. Furthermore, the antioxidant capacity revealed that red fruits exhibited higher antioxidant levels than green fruits. Color analysis showed that red fruits had higher chroma and hue angle values, indicating their brighter and more intense red color than green fruits. The morphological changes in fruit width, length, and weight can be attributed to shading treatments and maturation stages. These results indicate the potential of piquin peppers to act as rich sources of bioactive compounds, emphasizing the benefits of shading as an effective strategy to improve the quality and quantity of phytochemical compounds in piquin peppers. Our findings provide substantial insights into the intricate relationship between maturation, shading treatments, and phytochemical composition, offering a path to improve the nutritional value and quality of piquin peppers.