Nitrogen fertilization alters fruit yield and quality traits of Lycium barbarum in Northwest China
WANG Chenwen1,2, LIU Jianguo1,2,*(), ZHU Xinting1, XU Jingjing3, ZHAO Zehe1, TENG Baoqin3
1Key Laboratory of Resource Environment and Sustainable Development of Oasis, College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China 2Engineering Research Center for Ecological and Environmental Damage Assessment of Gansu Province, Lanzhou 730070, China 3Forestry Technique Extension Station of Gansu Province, Lanzhou 730046, China
Lycium barbarum L., valued for its potential immunomodulatory and metabolism-regulating functions, contains abundant bioactive compounds, including polysaccharides and betaine. The global demand for L. barbarum has grown rapidly at an annual rate exceeding 10.00%. Northwest China is the principal cultivation region. However, the highest urea application rate has induced soil acidification and nutrient imbalance, threatening the sustainability of this agricultural system. A three-year field experiment was conducted in the Wuwei oasis irrigation area to assess how different nitrogen (N) application rates affected fruit yield, fruit quality traits, and soil physicochemical properties. Four N rates, N0, N1, N2, and N3, supplied 0.00, 161.00, 322.00, and 483.00 kg N/hm2, respectively, and a non-fertilized blank control (BLK) was included. Yield, betaine, polysaccharides, total flavonoids, soluble solids, soil pH, soil organic matter (SOM), total phosphorus (TP), available phosphorus (AP), and soil enzyme activities were determined. Compared with the BLK, N2 increased the fruit yield from 933.24 to 2899.71 kg/hm2, an approximately threefold increase. Conversely, the highest N input decreased the soil pH and SOM in the 20-40 cm layer while increasing the surface soil electrical conductivity (EC). Under N3, the total flavonoid and betaine contents decreased by 14.78% and 55.32%, respectively. Thus, moderate N application improved fruit yield while maintaining fruit quality, whereas the highest N input reduced key functional components and enhanced the risk of soil degradation. These findings provide insights for optimizing N management in L. barbarum cultivation within arid regions.
Received: 02 April 2026
Published: 30 September 2026
Conceptualization: WANG Chenwen; Methodology: LIU Jianguo; Formal analysis: ZHU Xinting; Writing - original draft preparation: ZHAO Zehe; Writing - review and editing: WANG Chenwen; Funding acquisition: WANG Chenwen, LIU Jianguo, XU Jingjing; Resources: XU Jingjing, TENG Baoqin; Supervision: WANG Chenwen, LIU Jianguo. All authors approved the manuscript.
WANG Chenwen, LIU Jianguo, ZHU Xinting, XU Jingjing, ZHAO Zehe, TENG Baoqin. Nitrogen fertilization alters fruit yield and quality traits of Lycium barbarum in Northwest China. Journal of Arid Land, 2026, 18(9): 1651-1666.
Fig. 1Sampling location in Dajing Town, Gulang County, Wuwei City, Gansu Province, China (a) and annual average temperature and annual precipitation from 2019 to 2021 in the study area (b)
Fig. 2Layout of the Lycium barbarum L. experimental plots. Each plot comprised 33 planting cells arranged in 3 rows and 11 columns. Individual cells measured 2.5 m×1.2 m and contained one centrally positioned L. barbarum plant. BLK denotes blank control (i.e., no fertilizer) and N0-N3 denote different N treatments with standard phosphorus (P) and potassium (K) supplementation, of which N0 denotes no N fertilizer, N1 denotes 161.00 kg N/hm2, N2 denotes 322.00 kg N/hm2, and N3 denotes 483.00 kg N/hm2.
Treatment
Urea (kg/hm2)
Equivalent N (kg N/hm2)
Calcium superphosphate (kg/hm2)
P2O5 (kg/hm2)
Potassium magnesium sulfate (kg/hm2)
K2O (kg/hm2)
BLK
0.00
0.00
0.00
0.00
0.00
0.00
N0
0.00
0.00
1000.00
≥160.00
800.00
192.00
N1
350.00
161.00
1000.00
≥160.00
800.00
192.00
N2
700.00
322.00
1000.00
≥160.00
800.00
192.00
N3
1050.00
483.00
1000.00
≥160.00
800.00
192.00
Table 1 Fertilization application level for Lycium barbarum L.
Fig. 3Effects of different N application rates on L. barbarum fruit yield and quality traits. (a), fruit yield; (b), 100-fruit weight; (c), protein content; (d), polysaccharide content; (e), soluble solids content; (f), betaine content; (g), total flavonoid content. Different lowercase letters indicate significant differences among treatments at P<0.05 level, according to Duncan's multiple range test. Error bars indicate the standard error (SE; n=4).
Fig. 4Soil physicochemical properties in the 0-20 and 20-40 cm layers under different N fertilization rates. (a), pH; (b), soil water content (SWC); (c), soil organic matter (SOM); (d), available nitrogen (AN); (e), available phosphorus (AP); (f), available potassium (AK); (g), total nitrogen (TN); (h), total phosphorus (TP); (i), total potassium (TK). Different lowercase letters indicate significant differences among treatments at P<0.05 level, according to Duncan's multiple range test. Error bars indicate the SE (n=4).
Fig. 5Soil enzyme activities under different N fertilization rates in the 0-20 and 20-40 cm layers
Fig. 6Soil electrical conductivity (EC) under different N fertilization rates in the 0-20 and 20-40 cm layers. Different lowercase letters indicate significant differences among treatments at P<0.05 level, according to Duncan's multiple range test. Error bars indicate the SE (n=4).
Fig. 7Redundancy analysis (RDA) of soil physicochemical properties to L. barbarum fruit traits. The red lines on the figure represent the soil physicochemical characteristics, and the black lines represent the plant fruit traits. The vector length reflects the strength of the association of each variable with the first two RDA axes. The angle between a soil-factor vector (red) and a fruit-trait vector (black) indicates their relationship: an acute angle indicates a positive association, an obtuse angle indicates a negative association, and an angle close to 90° indicates a weak association.
Fig. 8Heatmap of correlations among soil physicochemical properties, enzyme activities, and L. barbarum fruit traits. Pearson correlation coefficients (r) are shown in the upper triangle, whereas circle color and size in the lower triangle indicate the direction and magnitude of the corresponding correlations. The diagonal, corresponding to self-correlations (r=1.00), is not displayed. Red indicates positive correlations and blue indicates negative correlations, with greater color intensity and larger circles indicating stronger correlations. *, significant at P<0.05 level, , significant at P<0.01 level.
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