Carbon nanotubes (CNT) are manufactured nanomaterials currently being used in medical and pharmaceutical devices, waste water treatment, and electronics. Because of their wide range of uses and small size, CNTs are an emerging and growing contaminant of concern. Many studies have been conducted on the fate and uptake of CNTs in plants. Exposure to CNTs resulted in both negative and positive effects on plant growth and reproduction, however the effects varied depending on plant species and type of CNT. This study tested the effects on heat or drought stressed tomatoes and drought stressed cotton exposed to multi-walled carbon nanotubes (MWCNTs) in soil. Tomato plants were grown in a greenhouse under regular growing conditions for 80 d during which time the greenhouse was held at an average temperature of 28°C (day and night). Cotton plants were not grown under heat stress. A subset of tomato and cotton plants was also subjected to slow-onset water deficit conditions. Photosynthetic response was measured before, during, and after the water deficit. Plants grown in soil mixed with CNTs showed delayed early growth (plant height). However after 80 days, plant height was similar for plants grown in CNT and control soil. CNT exposure to tomato plants resulted in decreased Water Use Efficiency (WUE) and above-ground biomass. Interestingly, CNT exposure had no effect on tomato plant photosynthetic response following water deficit stress or recovery. In contrast, photosynthetic differences were seen in cotton plants. Results of past studies have varied between plant species and type of CNT. However, the effects on plant growth of the interaction between environmental stress and the presence of CNTs is still not fully understood. Therefore, more research should be conducted on various crop species grown in CNT contaminated soil at varying concentrations under additional environmental stress.<br/>

Determining phytotoxicity of carbon nanotubes in heat and drought stressed crops

253rd National Meeting (2017)

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