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| DOI：10.13522/j.cnki.ggps.2025357 |
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| Effects of subsurface drip irrigation amount on soil water-salt distribution, root growth and fruit yield of dwarf apple orchards in Southern Xinjiang |
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Han Cailu, Gao Yang, Ma Shoutian, Li Sen
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Institute of Farmland Irrigation, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China
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| Abstract: |
| 【Objective】Subsurface drip irrigation can improve water-use efficiency of apple orchards in arid regions, but excessive irrigation wastes water, whereas insufficient irrigation risks salt accumulation and constrains root growth. This study aimed to identify the optimal subsurface drip irrigation amount that can balances soil water-salt dynamics, root growth, fruit yield, and water-use efficiency in densely planted dwarf apple orchards in Southern Xinjiang.【Method】A field experiment was conducted in Alar, Xinjiang, from April to October 2024. Irrigation was applied when the cumulative difference between evapotranspiration and precipitation reached 27 mm. Three irrigation amounts were compared: 27 mm (I27), 22.5 mm (I22.5) and 18 mm (I18). During the experiment, two-dimensional distribution of soil water and salinity around the drip emitters, root distribution, fruit yield, and irrigation water-use efficiency were measured. 【Result】Compared with I27, I22.5 and I18 reduced the average soil water content over the entire growth period by 18.2% and 24.5%, respectively, while increasing soil salinity by 26.7% and 51.0%, respectively. Under moderate water deficit (I22.5), soil salinity in the main root zone (0-60 cm) remained below the salt-tolerance threshold, 4.7 g/kg, whereas insufficient leaching under I18 resulted in significant salt accumulation in the middle and deep soil layers. Driven by soil water and salt gradients, I22.5 and I18 reduced root length density by 30.5% and 40.0%, respectively, compared with I27 (0.75 cm/cm3), while I22.5 shifted the depth of peak root distribution downward by 10 cm, to 30 cm. Both fruit yield and irrigation water-use efficiency showed a unimodal response to decreasing irrigation among, initially increasing and then decreasing. I22.5 produced the highest fruit yield (25.29 t/hm2) and irrigation water-use efficiency (4.01 kg/m3).【Conclusion】Under the experimental conditions, applying 22.5 mm of irrigation when the cumulative difference between evapotranspiration and precipitation reached 27 mm was optimal for densely planted dwarf apple orchards in Southern Xinjiang. It provides the best balance among yield stability, water saving, salinity control, and irrigation water-use efficiency. |
| Key words: apple subsurface drip irrigation irrigation quota water-salt root yield |
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