Increasing Se concentration in maize grain with soil- or foliar-applied selenite on the Loess Plateau in China

- Soil and foliar Se application did not affect maize grain yield.
- Soil and foliar Se application are effective to elevate maize grain Se content.
- Se content in maize grain is linearly correlated with Se application rates.
- Foliar Se application realised higher grain Se recovery than soil application.

Selenium (Se) is an essential mineral nutrient for animal and human growth. Deficiency in this element is a worldwide nutrition problem. Thus, this study determined the potential of increasing Se content in maize grain by using various Se fertiliser application techniques to improve the nutritional status of local residents. Field experiments were conducted on the Loess Plateau for two growing seasons to investigate the effects of different Se fertiliser application methods and application rates on the Se content in maize grain as well as the Se recovery, yield and status of other nutrients in maize grain under rain-fed conditions. Results show that soil and foliar Se applications exhibited no significant effects on maize biomass and grain yield as well as N, P, K, Ca, Mg, Fe, Mn, Cu and Zn contents in maize grain. However, both foliar and soil Se applications significantly improved the Se content in maize grain. Selenium content in maize grain is found to be linearly correlated with Se application rates, increasing from 0.12 μg kg−1 to 0.33 μg kg−1 by soil application at 1 g of Se ha−1 and from 8.23 μg kg−1 to 8.67 μg kg−1 by foliar application at the same rate. Foliar application of Se showed higher Se recoveries in the grain compared with soil Se application: the former exhibited a maximum grain Se recovery rate of 52‰ and 106‰ in maize during the first and second growing seasons, respectively, whereas the latter was only 1.69‰ and 0.95‰, respectively. On the Loess Plateau in China, both soil and foliar Se applications effectively improved the Se content in maize grain. Compared with soil Se application, foliar Se application can improve the grain Se content in maize at reduced costs.