The role of nanosilica in antioxidant production, nutrition and photochemical efficiency to mitigate sulfur deficiency in Capsicum annuum L.

Sulfur deficiency limits the development of bell pepper in various cultivation regions worldwide. The use of nanosilica is a promising alternative to mitigate the nutritional impairments caused by stress; however, its efficacy in bell pepper under sulfur-deficiency and its potential benefits for non-stressed plants remain unclear. This study aimed to investigate the impact of sulfur-deficiency on bell pepper and evaluate the effects of nanosilica in mitigating these effects, as well as to explore its benefits under sulfur-sufficient conditions. The experiment was conducted in a greenhouse using a 2 × 2 factorial design with two sulfur conditions (sufficiency and deficiency) and two nanosilica application conditions (presence and absence), with 5 replicates Our findings revealed that sulfur deficiency specifically impaired plant growth by disrupting N/P homeostasis (Shoot: -60.1 % and root: -39.3 %), reducing nutrient use efficiency for biomass production due to the accumulation of unmetabolized amino acids (+310.9 %) and sugars (+133.4 %), and decreasing antioxidant compounds such as anthocyanins (-75.1 %) and carotenoids (-73.5 %). These changes led to pigment degradation (-80.1 %) and compromised photochemical efficiency (-18.5 %). Nanosilica application alleviated these adverse effects by enhancing phosphorus uptake (Shoot: +15.5 % and root: +17.1 %) and sulfur cycling, resulting in greater sulfur accumulation within the plant (Shoot: 43.0 % and root: 40.7 %). This improvement supported sugar metabolism (-7.0 %), increased antioxidant and chlorophyll production (+19.4 %), and restored photosystem II efficiency (+12.0 %). In sulfur-sufficient plants, nanosilica notably promoted growth by increasing the biosynthesis of antioxidants (ascorbic acid (+19.5 %) and flavonoids (+26.1 %)) and improving nitrogen (+5.1 %) and phosphorus (+2.7 %) use efficiency in shoot. In conclusion, this research highlights novel benefits of nanosilica in bell pepper, positioning as an effective tool not only for mitigating sulfur nutritional stress, but also for optimizing plant growth under adequate nutrient conditions.