The effect of bio and nano silicon sources on sweet pepper growth in greenhouses under LED light conditions

The sweet pepper, a plant characterized by an extended growing period, requires adequate light and nutrition for growing in the greenhouse. Silicon (Si) plays a crucial role in horticulture production by enhancing plant resistance to various stresses, promoting healthier root development, and improving overall crop quality and yield. Therefore, this study aimed to explore how different sources of silicon and light impact the growth, physiological characteristics, and mineral composition of bell peppers in a greenhouse setting. The experiment employed a factorial design within completely randomized design (CRD) with three replications. The silicon treatment comprised seven levels: non-silicon (C), potassium silicate (Si1 and Si2), nano silicon (N-Si1 and N-Si2), and bio silicon (B-Si1 and B-Si2) at two concentrations of 100 and 150 ppm. There were two light treatments: sunlight (control) and LED light. Overall, the results revealed that compared with sunlight, LED light enhanced most of the studied traits, including shoot length, number of flowers, photosynthetic pigments, phenol, flavonoids, and DPPH. Among the different sources of Si, the application of Si1 under LED light resulted in the greatest number of flowers and DPPH. N-Si1 enhanced shoot length and phenol content by 35 % and 21 %, respectively, compared to those of the control. Compared with other sources of Si, N-Si2 improved photosynthetic pigments under LED light, and the application of B-Si played a significant role in improving the contents of pepper minerals such as calcium (Ca), magnesium (Mg) and Si under sunlight. Overall, it can be inferred that compared with sunlight, LED light enhanced most of the investigated traits except for minerals. Additionally, among the various silicon treatments, a concentration of 100 ppm for each source demonstrated greater effectiveness in improving the traits compared to 150 ppm.