Titanium dioxide nanoparticle (nano-TiO₂), as an excellent UV absorbent and photo-catalyst, has been widely applied in modern industry, thus inevitably discharged into environment. We proposed that nano-TiO₂ in soil can promote crop yield through photosynthetic and metabolic disturbance, therefore, we investigated the effects of nano-TiO₂ exposure on related physiologic-biochemical properties of rice (Oryza sativa L.). Results showed that rice biomass was increased >30% at every applied dosage (0.1–100 mg/L) of nano-TiO₂. The actual photosynthetic rate (Y(II)) significantly increased by 10.0% and 17.2% in the treatments of 10 and 100 mg/L respectively, indicating an increased energy production from photosynthesis. Besides, non-photochemical quenching (Y(NPQ)) significantly decreased by 19.8%–26.0% of the control in all treatments respectively, representing a decline in heat dissipation. Detailed metabolism fingerprinting further revealed that a fortified transformation of monosaccharides (D-fructose, D-galactose, and D-talose) to disaccharides (D-cellobiose, and D-lactose) was accompanied with a weakened citric acid cycle, confirming the decrease of energy consumption in metabolism. All these results elucidated that nano-TiO₂ promoted rice growth through the upregulation of energy storage in photosynthesis and the downregulation of energy consumption in metabolism. This study provides a mechanistic understanding of the stress-response hormesis of rice after exposure to nano-TiO₂, and provides worthy information on the potential application and risk of nanomaterials in agricultural production.

二氧化钛纳米粒子（nano-TiO ₂）作为一种优良的紫外线吸收剂和光催化剂，已在现代工业中得到广泛应用，不可避免地排入环境。我们提出土壤中的纳米TiO ₂可以通过光合作用和代谢紊乱来促进作物产量，因此，我们研究了纳米TiO ₂暴露对水稻（Oryza sativa L.）相关生理生化特性的影响。结果表明，每施用纳米TiO ₂（0.1–100 mg / L），水稻生物量增加> 30％。在10 mg / L和100 mg / L的处理中，实际的光合速率（Y（II））分别显着增加了10.0％和17.2％，表明光合作用产生的能量增加。此外，在所有处理中，非光化学猝灭（Y（NPQ））分别较对照显着下降了19.8％–26.0％，这代表了散热量的下降。详细的代谢指纹图谱进一步表明，单糖（D-果糖，D-半乳糖和D-talose）向二糖（D-纤维二糖和D-乳糖）的强化转化伴随柠檬酸循环减弱，证实了柠檬酸循环的减少。代谢中的能量消耗。所有这些结果阐明了纳米TiO ₂通过光合作用中能量存储的上调和代谢中能量消耗的下调来促进水稻生长。这项研究提供了机械原理来了解水稻暴露于纳米TiO ₂后的应力响应，并提供了有关纳米材料在农业生产中的潜在应用和风险的有价值的信息。