Effects of fullerene C60 on the uptake of nitrogen and mineral elements in crops using the synchrotron radiation microscopic X-ray fluorescence spectrometry (SR-μXRF) and stable isotope labeling

The unique characteristics of fullerene (C60) have attracted great attention in the agricultural field. However, it remains unclear about its potential effects of nitrogen sources and the uptake of various mineral nutrients required for plant growth. In this study, we take advantage of the stable isotope 15N labeling technique combined with synchrotron radiation microscopic X-ray fluorescence spectrometry (SR-μXRF) to investigate efficiently the effects of C60 (10.0 mg/g) on the uptake level of nitrogen and multiple trace mineral elements in three common crops (maize, wheat, and soybean). The results showed that C60 had different effects on the uptake of nitrogen and 15 trace mineral elements in different types of crops. C60 significantly decreased the uptake rate of nitrate-nitrogen in maize and soybean by 52.4% and 66.1%, respectively, but it had no significant effects on the uptake of ammonium-nitrogen. By contrast, C60 had no significant effect on the uptake of nitrate-nitrogen in wheat, but it significantly increased the uptake rate of ammonium-nitrogen by more than 3 folds. In addition, C60 tended to change the uptake of 15 trace elements in wheat, maize and soybean, but significant differences were only found in the uptake of K, Ca and Fe in different tissues of three crops. Our results suggest that the joint analysis technology not only facilitates the simultaneous comparison of the uptake of total trace nutrients (including organic and inorganic nutrients) in plants, but also enables us to obtain the impact of nanomaterials on plant growth. C60 can improve the uptake of nitrogen and change trace mineral elements in crops, possibly avoiding the damage to soils and the environment caused by the overuse of fertilizers and increasing the yield quantity and quality of crops.