Interactive effects of copper oxide nanoparticles and arsenic on rice (O.sativa japonica ’Koshihikari’) plant growth and development.

Abstract

The emerging applications of nanomaterials (NMs) encompass a wide range of industries, including agriculture (e.g., as fertilizers, pesticides, and biosensors). NMs applied in the crop-field may influence plant growth and uptake of heavy metal(loid)s including arsenic (As). Being ubiquitous in the environment and readily bioavailable in aquatic system, As is taken up by rice plants, causes phytotoxicity and accumulates in rice grains. Classified as a Class I carcinogen and causing many diseases, As in rice grains potentially causes human health effects, particularly for infants who are eating rice to transition from breast milk to solid food, and Asian populations with regular daily rice consumption. Although As in water can be removed dramatically by copper oxide nanoparticles (nCuO) due to their high adsorption capacity for As, the interaction of nCuO and As has not been well elucidated on rice plant growth and As accumulation. This project was the first to investigate the interaction of nCuO and As on rice (Oryza sativa japonica’Koshihikari’) plant growth and development during a life cycle (from seed germination to seed maturation). The effects of nCuO and As were determined, individually and interactively, on rice seed germination and early seedling growth in sand and an artificial soil mixture of clay and topsoil. A greenhouse study on the life cycle growth of rice plants in the artificial soil mixture approximated the real agriculture scenario and identified the nCuO dependent acceleration of heading process of rice plants. Particularly, As accumulation in dehusked rice grains was decreased by nCuO to 128 ng/g, 36% lower than the WHO maximum safe concentration of As in white rice (200 ng/g) for humans. Arsenic distribution and speciation inside the plant growth were also affected by nCuO. Transgenerational effects of nCuO and As were also verified on seed germination and early seedling growth of rice plants in this project. These results contribute to the fundamental database of endpoint effects on rice plants, direct future research about wide-scale application of NMs in crop field as fertilizers or amendments, and provide insightful information to investigate the mechanism of the interaction between nCuO and As on plant growth.