Full
Outline
Objective This study aims to investigate the specific mechanisms by which nitrogen application regulates rhizosphere bacterial denitrification pathways in salt-affected farmland， thereby promoting sunflower root growth and yield. Methods Field plot experiments with drip irrigation under plastic mulch were conducted in sunflower farmland from 2023 to 2024. Four nitrogen application levels were set： the local conventional nitrogen application rate as control （CK： 200 kg/hm2）， 25% nitrogen reduction （N1： 150 kg/hm2）， 50% nitrogen reduction （N2： 100 kg/hm2）， and 75% nitrogen reduction （N3： 50 kg/hm2）. Results The two-year experiments demonstrated that moderate nitrogen reduction improved the rhizosphere soil environment in salt-affected farmland and promoted sunflower root growth and yield formation. Compared with CK， both N1 and N2 treatments significantly increased Ca2+ （17.22%， 10.56%） and Mg2+ （34.75%， 25.40%） contents in rhizosphere soil at the budding stage， and reduced and contents. Furthermore， N1 treatment significantly promoted oxalic acid and citric acid secretion by root at the budding stage （59.07% and 60.11%）， and N2 treatment significantly promoted formic acid secretion by root at both the budding stage and the maturity stage. Regarding functional genes， N1， N2， and N3 treatments reduced the relative abundance of denitrifying genes narG， nirK， and nirS， whereas N1 treatment increased the abundance of the nosZ gene and altered the composition of nosZ-type bacterial communities， including increasing the relative abundance of nosZ-type Acidobacteria and Proteobacteria. Regarding crop growth and yield formation， N1 and N2 treatments significantly increased root surface area density （RSAD） at the flowering stage and root length density （RLD） at the budding stage. Over two years， N1 treatment significantly increased sunflower 100-seed weight （9.07%）， seed weight per head （9.08%）， and yield （5.05%）. In contrast， N2 and N3 treatments significantly reduced RSAD values （23.66%， 29.46%）， 100-seed weight （21.67%， 29.51%）， and seed weight per head （21.66%， 29.49%） at the maturity stage. Conclusion A 25% nitrogen reduction treatment has a potential inhibitory effect on the initial stage of denitrification （→NO） and a potential promoting effect on the complete denitrification process （N2O→N2） in rhizosphere soil. This not only suppresses nitrogen loss from salt-affected farmland at the source but also promotes N2 reduction. Meanwhile， it shows significant advantages in promoting plant root growth and yield formation， as well as improving the rhizosphere soil ionic environment. These findings provide a theoretical basis for scientific nitrogen application and nitrogen loss control in the Tumuchuan Plain irrigation district.
163
78
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
关闭全屏
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62662699(Operation and Technical Support)
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
