地下滴灌条件下夏玉米适宜水氮策略及其微生物群落结构和功能研究OA

To determine the optimal water-nitrogen strategy for summer maize under subsurface drip irri-gation(SDI)and reveal the underlying microbial mechanisms,a field experiment was conducted in a typical summer maize region of the Guanzhong Plain,Shaanxi,China.Four irrigation regimes(A1-A4)were designed using a root-zone soil-water threshold approach(165,245,365,and 415 m3/hm2,three irrigations per growth stage),combined with three nitrogen rates(B1-B3:100,140 and 180 kg N/hm2),yielding 12 water-nitrogen treatments in total.Plant height,leaf area index,grain yield,wa-ter use efficiency(WUE)and nitrogen use efficiency(NUE)were measured.Soil bacterial communities were characterized by 16S rRNA sequencing,and nitrogen-cycling functions were inferred by FAPROTAX and co-occurrence network analysis.The results showed that A2B2(C5)was the optimal combination.Compared with the low-water/low-N treatment(C1),its yield increased from(4,500±320)to(7,800±220)kg/hm2(～73%),WUE increased from(1.50±0.12)to(1.92±0.08)kg/(mm·hm2)(～28%),and NUE reached 42.69%±2.10%.Microbial analyses indicated that A2B2 enriched nitrogen-fixing taxa and reduced denitrification potential;the relative abundance of aerobic free-living nitrogen fixers reached 62.55%±2.50%.Overall,moderate irrigation with medium N input under SDI synergistically improved agronomic performance,resource use efficiency and microbial N-cycling functions.It is recom-mended to adopt an irrigation quota of 245 m3/hm2 coupled with 140 kg N/hm2 fertilizer applied via split fertigation for summer maize under SDI.These findings can provide a reference for the advancement of precision water-fertilizer regulation and nitrogen reduction with enhanced efficiency.