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

Effects of combined application of selenium and nitrogen fertilizers on selenium and nitrogen accumulation in oat plants,rhizospheric soil microbial community,and metabolites

为探明硒氮配施对燕麦硒农艺强化和氮积累同步提升的可行性及其对根际土壤微生物群落的改善作用,采用田间试验结合盆栽生土试验,研究黄土高原缺硒区土壤基施不同用量硒氮肥对花后燕麦地上部植株硒、氮积累与籽粒产量和根际土壤微生物群落特征及代谢物的影响.试验采用二因素裂区设计,主区为基施氮肥,3个水平(N0:0 kg/hm^(2);N1:120 kg/hm^(2);N2:240 kg/hm^(2));副区为配施硒肥,4个水平(Se0:0 g/hm^(2);Se1:75 g/hm^(2);Se2:150 g/hm^(2);Se3:375 g/hm^(2)).结果表明:单施硒肥、氮肥及硒氮配施对花后燕麦植株硒氮积累影响显著;从扬花期到成熟期,茎叶硒氮积累明显向穗部及籽粒转移.在低氮高硒或低硒高氮处理中,硒、氮积累呈协同促进关系;而在高氮高硒处理中,硒、氮积累存在竞争性抑制关系.整体而言,以N2Se2(240 kg/hm^(2)+150 g/hm^(2))处理下燕麦各器官硒、氮含量和籽粒产量达最高(分别为136.52-193.29μg/kg,29.33-32.02 g/kg,1263.8-1970.9 kg/hm^(2)).硒氮合理配施(N2Se2)明显促进了土壤微生物功能菌群代谢;功能菌群主要代谢物与植株各器官硒氮含量亦呈正相关关系.综上所述,在黄土高原缺硒地区,土壤基施适宜用量的氮肥和硒肥,有利于协同提升燕麦地上部各器官硒氮积累及籽粒产量,改善土壤微生物优势菌门和优势菌属,促进功能菌群代谢,以N2Se2(240 kg/hm^(2)+150 g/hm^(2))为最优施肥处理.

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 splitplot design was used to conduct these experiments,with application of nitrogen fertilizer at three levels(N0:0 kg/hm^(2);N1:120 kg/hm^(2);N2:240 kg/hm^(2))and selenium fertilizer at four levels(Se0:0 g/hm^(2);Se1:75 g/hm^(2);Se2:150 g/hm^(2);Se3:375 g/hm^(2)).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/hm^(2)+150 g/hm^(2)),the contents of selenium and nitrogen in various organs and oat grain yield were the highest(136.52-193.29μg/kg,29.33-32.02 g/kg,1263.8-1970.9 kg/hm^(2),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/hm^(2)+150 g/hm^(2))was the best fertilizer treatment.