Effects of foliar selenium application on growth and rhizospheric soil micro-ecological environment of Atractylodes macrocephala Koidz

Atractylodes macrocephala (A. macrocephala), a famous medicinal herb in China, is widely cultivated and consumed in China with various beneficial effects. Numerous studies have shown that selenium (Se) plays an important role in promoting plant growth, although Se has not been considered an essential element for higher plants. The objectives of this research were to determine the effects of foliar Se application (0, 2.5, 5.0, 10.0 and 20.0 mg m(−2) Se in sodium selenite, sprayed monthly from May to August) on the growth and rhizospheric soil micro-ecological environment of A. macrocephala, and explore the possible mechanisms underlying plant response to foliar Se application through a field experiment. The results were: The foliar application of 5.0 mg m(−2) Se significantly increased the survival rate of A. macrocephala compared to the control. The yield of A. macrocephala was increased when the Se level maintained belowed 10.0 mg m(−2) but decreased when Se level reached 20.0 mg m(−2). The Se content in the rhizome of A. macrocephala showed a significant positive correlation with the Se level, while the insect attack rate was significantly negatively correlated with the Se level. However, foliar Se application hardly affected the concentration of bioactive compound atractylenolide in the rhizome of A. macrocephala. Notably, the application of foliar Se changed the content of partial soil nutrients, microbial diversity and composition in the rhizosphere soil of A. macrocephala. Bacterial diversity was positively correlated with A. macrocephala growth whereas fungal diversity was negatively correlated, suggesting that microbial diversity in the rhizosphere soils is closely related to plant growth. Moreover, correlation analysis showed that available potassium, Burkholderia and Cupriavidus in rhizospheric soil might be critical factors for promoting the growth of A. macrocephala. Overall, the foliar application of Se at moderate concentration was beneficial for the growth of A. macrocephala, and 5.0-10.0 mg m(−2) Se level was the optimum. Our findings revealed novel insights into the response of A. macrocephala to foliar Se application from plant growth, rhizospheric soil nutrient and microbial community composition .