Silicon Nanoparticles Enhance Arsenic Stress Tolerance in Cicer arietinum L. through Physiological and Biochemical Modulation

Arsenic contamination poses a significant threat to agricultural productivity and food security, especially in Cicer arietinum L. (chickpea). This study evaluates the potential of silicon nanoparticles (SiNPs) to mitigate arsenic stress in C. arietinum (Noor 2022). The experiment was conducted at The Islamia University of Bahawalpur using a randomized complete block design (RCBD) with a factorial arrangement and three replications. A pot experiment was conducted using seven treatments comprising various concentrations of SiNPs applied alone or combined with arsenic [T0 (control, no SiNPs), T1 (3.5% SiNPs), T2 (7% SiNPs), T3 (10.5% SiNPs), T4 (3.5% SiNPs + 30 ppm Ar), T5 (7% SiNPs + 30 ppm Ar), and T6 (10.5% SiNPs + 30 ppm Ar)]. SiNPs were applied as foliar sprays in three splits from the second to fourth weeks after sowing. Morphological, physiological, and biochemical parameters were assessed, including chlorophyll content, total soluble proteins, proline, and antioxidant enzyme activities. The results demonstrated that SiNPs significantly enhanced stress tolerance in chickpea plants. At 10.5% SiNPs, chlorophyll content increased by 35%, carotenoids by 42%, and proline by 68% compared to arsenic-stressed plants without SiNPs, indicating improved photosynthetic efficiency and osmotic adjustment. Antioxidant enzyme activities, including peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), increased by 50%, 47%, and 53%, respectively, mitigating oxidative damage. Soluble sugars and phenolic content also rose by 28% and 32%, respectively, under 10.5% SiNPs. However, when combined with arsenic, some antagonistic effects were observed, with a slight decrease in chlorophyll and antioxidant activity compared to SiNPs alone. These findings suggest that SiNPs are a promising tool for improving crop resilience in arsenic-contaminated soils, offering insights into sustainable agricultural practices. Further research is warranted to explore long-term impacts and optimize application strategies.