| Effects of water\|nitrogen coupling on soil nitrogen dynamics, root morphology, and yield formation of baby pak choy |
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| DOI：10.7606/j.issn.1000-7601.2026.04.10 |
| Key Words: Brassica pekinensis L. water\|nitrogen coupling soil nitrogen root morphology dry matter accumulation water\|nitrogen use efficiency |
| Author Name | Affiliation | | LV Ting | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China | | SHI Wan’en | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China | | YAO Yalan | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China | | ZHANG Yuezhen | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China | | CHEN Shunguo | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China | | YU Yarong | Wuwei Municipal Water Conservancy Science and Technology Promotion Center, Wuwei, Gansu 733000, China
Gansu Wuwei Central Irrigation Experiment Station, Wuwei, Gansu 733000, China |
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| Abstract: |
| To investigate the synergistic mechanisms of water and nitrogen for achieving high yield and high efficiency in baby pak choy under mulched drip irrigation in the cold and arid region of Northwest China, a field experiment was conducted in 2024 in the cold\|arid area of Wuwei, Gansu Province. A split\|plot design was adopted, with irrigation level as the main plot, the growing\|season irrigation treatments comprised three gradients: high water (W1, 100% of conventional irrigation amount), medium water(W2, 20% reduction from conventional), and low water(W3, 40% reduction from conventional). Nitrogen application level was set as the sub\|plot, including three gradients: high nitrogen (N1, 100% conventional topdressing rate), medium nitrogen (N2, 80% conventional topdressing rate), and low nitrogen (N3, 60% conventional topdressing rate), with local conventional water\|nitrogen management (W1N1) as the control. The effects of water\|nitrogen coupling on the spatiotemporal distribution of soil nitrogen in the root zone, root morphology, dry matter accumulation and partitioning, economic yield, and water\|nitrogen use efficiencies were systematically analyzed, and path analysis was employed to identify the key driving factors of yield formation. The results showed that water\|nitrogen coupling significantly affected the spatiotemporal dynamics of soil inorganic nitrogen, with nitrate nitrogen being the dominant form, exhibiting a general pattern of surface accumulation at the rosette stage, a sharp decline at the heading stage, and downward migration to deeper layers at the harvest stage. Under the W2N2 treatment, the nitrate nitrogen content in the 20-40 cm soil layer at the heading stage was the lowest, being 73.34% lower than that of the control. At harvest, the residual nitrate nitrogen in the deep layer (40-60 cm) of W2N2 was 49.29% lower than that in the treatment with the highest residue (W3N1), effectively mitigating the risk of nitrogen leaching. For root morphology, the W2N2 treatment showed superior comprehensive root traits, with total root length, root surface area, and root volume at harvest increased by 89.44%, 69.27%, and 22.95%, respectively, compared with the control. Regarding dry matter accumulation, the aboveground dry matter accumulation of the W2N2 treatment at harvest was significantly increased by 29.82% relative to the control. Path analysis revealed that aboveground dry matter accumulation was the primary core factor determining yield(direct path coefficient of 1.552), while root surface area was the only root trait that exhibited both a positive direct effect (0.158) and a positive indirect effect (1.302). The W2N2 treatment achieved an economic yield of 100 605.35 kg·hm-2 for baby pak choy, representing a 36.70% increase over the control. It also ranked first in both water use efficiency and nitrogen partial factor productivity, which were increased by 44.14% and 54.80%, respectively, compared with the control. Overall, the W2N2 treatment (total irrigation quota of 1 410 m3·hm-2 over the whole growth period and total nitrogen application of 422.1 kg·hm-2) can simultaneously achieve the multiple objectives of yield increase, water saving, and nitrogen reduction in baby pak choy by establishing a beneficial synergistic system of “efficient root nutrient uptake\|efficient nitrogen utilization in the root zone\|coordinated canopy growth”. |
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