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Resource-based water shortages, uncoordinated irrigation, and fertilization are prevalent challenges in agricultural production. The scientific selection of appropriate water and fertilizer management methods is important for improving the utilization efficiency of agricultural resources and alleviating agricultural non-point source pollution. This study focused on wolfberry and compared the effects of four irrigation levels [full irrigation (W0, 75%-85% θ f ), slight water deficit (W1, 65%-75% θ f ), moderate water deficit (W2, 55%-65% θ f ), and severe water deficit (W3, 45%-55% θ f )] and four nitrogen application levels [no nitrogen application (N0, 0 kg·ha -1 ), low nitrogen application (N1, 150 kg·ha -1 ), medium nitrogen application (N2, 300 kg·ha -1 ), and high nitrogen application (N3, 450 kg·ha -1 )] on soil nitrate nitrogen (NO 3 - -N) transport, plant nitrogen allocation, and soil nitrous oxide (N 2 O) emissions during the harvest period of wolfberry. And this study used CRITIC-entropy weights-TOPSIS model to evaluate 16 water and nitrogen regulation models comprehensively. The results revealed the following: (1) The NO 3 - -N content of the soil decreased with increasing horizontal distance from the wolfberry. It initially decreased, then increased, and finally decreased with an increase in soil depth. The average NO 3 - -N content in the 0-100 cm soil layer ranged from 3.95-13.29 mg·kg -1 , indicating that W0 > W1, W2, W3, and N3 > N2 > N1 > N0. (2) The soil NO 3 - -N accumulation ranged from 64.45-215.27 kg·ha -1 under varying water and nitrogen levels, demonstrating a decreasing trend with increasing horizontal distance. The NO 3 - -N accumulation at each horizontal distance increased with increasing irrigation and nitrogen application. The NO 3 - -N accumulation of W0N3 treatment increased by 5.55%-57.60% compared with the other treatments. (3) The total nitrogen content and nitrogen uptake in all wolfberry organs were W1 > W0 > W2 > W3, and N2 > N3 > N1 > N0. The maximum total nitrogen content and nitrogen uptake in W1N2 treatment were 3.25% and 27.82 kg·ha -1 in the roots, 3.30% and 57.19 kg·ha -1 in the stems, 3.91% and 11.88 kg·ha -1 in the leaves, and 2.42% and 63.56 kg·ha -1 in the fruits, respectively. (4) The emission flux and total emission of N 2 O increased with increasing irrigation and nitrogen application. The emission flux exhibited a transient peak (116.39-177.91 ug·m -2 ·h -1 ) after irrigation. The intensity of N 2 O emissions initially decreased and then increased with an increase in the irrigation amount. It also initially increased with increasing nitrogen application amount, then decreased, and finally increased again. The maximum emission intensity was observed under the W3N3 treatment (0.23 kg·kg -1 ). The N 2 O emission coefficients ranged from 0.17%-0.39%, in the order of W0 > W1 > W2 > W3 (except for N1) and N1 > N2 > N3. (5) Under varying water and nitrogen concentrations, N 2 O emission flux showed a positive linear correlation with soil pore water content and NO 3 - -N content and a negative linear correlation with soil temperature. The comprehensive evaluation revealed that a slight water deficit (65%-75% θ f ) combined with medium nitrogen application (300 kg·ha -1 ) decreased soil NO 3 - -N leaching, increased nitrogen uptake, and reduced N 2 O emission. These findings can serve as a reference for improving the efficiency and reducing emissions of wolfberry in the Yellow River irrigation region of Gansu Province and in similar climate zones., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tian, Wang, Yin, Ma, Jia, Kang, Qi, Gao, Jiang, Li and Xiao.)

To address the problems of extensive field management, low productivity, and inefficient water and fertilizer utilization in wolfberry ( Lycium barbarum L.) production, an appropriate water and nitrogen regulation model was explored to promote the healthy and sustainable development of the wolfberry industry. Based on a field experiment conducted from 2021 to 2022, this study compared and analyzed the effects of four irrigation levels [75%-85% θ f (W0, full irrigation), 65%-75% θ f (W1, slight water deficit), 55%-65% θ f (W2, moderate water deficit), and 45%-55% θ f (W3, severe water deficit)] and four nitrogen application levels [0 kg·ha -1 (N0, no nitrogen application), 150 kg·ha -1 (N1, low nitrogen application), 300 kg·ha -1 (N2, medium nitrogen application), and 450 kg·ha -1 (N3, high nitrogen application)] on soil water distribution, soil nitrate nitrogen (NO 3 - -N) migration, yield, and water-nitrogen use efficiency of wolfberry. The soil moisture content of the 40-80 cm soil layer was higher than those of 0-40 cm and 80-120 cm soil layer. The average soil moisture content followed the order of W0 > W1 > W2 > W3 and N3 > N2 > N1 > N0. The NO 3 - -N content in the 0-80 cm soil layer was more sensitive to water and nitrogen regulation, and the cumulative amount of NO 3 - -N in the soil followed the order of W0 > W1> W2 > W3 and N3 > N2 > N1 > N0 during the vegetative growth period. There was no evidently change in soil NO 3 - -N accumulation between different treatments during the autumn fruit. The yield of wolfberry under the W1N2 treatment was the highest (2623.09 kg·ha -1 ), which was 18.04% higher than that under the W0N3 treatment. The average water consumption during each growth period of wolfberry was the highest during the full flowering period, followed by the vegetative growth and full fruit periods, and the lowest during the autumn fruit period. The water use efficiency reached a peak value of 6.83 kg·ha -1 ·mm -1 under the W1N2 treatment. The nitrogen uptake of fruit and nitrogen fertilizer recovery efficiency of fruit first increased and then decreased with increasing irrigation and nitrogen application. The treatment of W1N2 obtained the highest nitrogen uptake of fruit and nitrogen recovery efficiency of fruit, which were 63.56 kg·ha -1 and 8.17%, respectively. Regression analysis showed that the yield and water-nitrogen use efficiency of wolfberry improved when the irrigation amount ranged from 315.4 to 374.3 mm, combined with nitrogen application amounts of 300.0 to 308.3 kg·ha -1 . Additionally, the soil NO 3 - -N residue was reduced, making it an optimal water and nitrogen management model for wolfberry planting. The present findings contribute novel insights into the production of wolfberry with saving water and reducing nitrogen, which helps to improve the level of wolfberry productivity in the Yellow River irrigation region of Gansu Province and other areas with similar climate., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Tian, Qi, Kang, Jia, Wang, Xiao, Gao, Wang, Lu and Chen.)