硒氮配施对燕麦植株硒氮积累及根际土壤微生物群落与代谢物的影响

To verify the feasibility of the combined application of selenium and nitrogen fertilizer for simultaneous selenium agronomic enhancement and nitrogen accumulation in oats and its effect on the rhizosphere soil microbial community, field experiments were carried out and combined into pots of raw soil experiments to explore the effect of different supplemented dosages of selenium nitrogen fertilizer on the accumulation of selenium and nitrogen in aboveground oat plants after the flowering stage, as well as the characteristics and metabolites of the rhizosphere soil microbial community in selenium-deficient areas of the Loess Plateau. A two-factor split-plot design was used to conduct these experiments, with application of nitrogen fertilizer at three levels (N0: 0 kg/hm²; N1: 120 kg/hm²; N2: 240 kg/hm²) and selenium fertilizer at four levels (Se0: 0 g/hm²; Se1: 75 g/hm²; Se2: 150 g/hm²; Se3: 375 g/hm²). The results showed that the single application of selenium, nitrogen, and selenium-nitrogen combination fertilizer had a significant effect on the accumulation of selenium and nitrogen in oat plants after the flowering stage; from the flowering stage to the mature stage, the accumulation of selenium and nitrogen in stems and leaves was significantly transferred to the panicles and grains. However, under low nitrogen and high selenium or low selenium and high nitrogen treatments, the accumulation of selenium and nitrogen showed a synergistic promoting relationship, whereas under high-nitrogen and high-selenium treatments, a competitive inhibitory relationship was observed between the accumulation of selenium and nitrogen. Overall, under N2Se2 treatment (240 kg/hm² + 150 g/hm² ), the contents of selenium and nitrogen in various organs and oat grain yield were the highest (136.52-193.29 μg/kg, 29.33-32.02 g/kg, 1 263.8-1 970.9 kg/hm², respectively). Moreover, the rational combination N2Se2 significantly promoted the metabolism of soil microorganism functional flora, and the main metabolites of the functional flora also showed positive correlations with selenium and nitrogen content in oat organs. In summary, in selenium-deficient areas on the Loess Plateau, the application of an appropriate amount of nitrogen and selenium fertilizers to the soil is beneficial for synergistically enhancing the accumulation of selenium and nitrogen in the aboveground organs of oats and grain yield, which promotes the dominant phylum and genus of soil microorganisms and the metabolism of functional microbial communities. Nonetheless, N2Se2 (240 kg/hm² + 150 g/hm²) was the best fertilizer treatment.