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The cultivation of Panax notoginseng has been plagued by a multitude of challenges, including recurrent diseases, suboptimal value, inadequate quality, and environmental degradation resulting from improper water and fertilizer management. To address these issues and improve the yield of P. notoginseng and its saponin content, this study endeavors to identify the optimal irrigation and fertilization levels in shaded environments in Yunnan Province in Southwest China. In this field experiment, three-year-old plants were tested to evaluate the effects of water, soluble organic fertilizers, and their combinations on plant growth, physiological parameters, yield, and saponin content. The experiment included 12 treatments with three types of irrigation (10 (W1), 15 (W2), and 20 (W3) mm), totaling 440, 660, and 880 mm, and four levels of the total amount of fertilization (F1 (60, total N 12.6, total P 5.5, and total K 10.5 kg ha−1), F2 (90, total N 18.9, total P 8.3, and total K 15.7 kg ha−1), F3 (120, total N 25.2, total P 11.0, and total K 20.9 kg ha−1), F4 (150, total N 31.5, total P 13.8, and total K 26.1 kg ha−1)). The randomized complete block design was used, with 36 plots in total and 3 replications. The study utilized the TOPSIS method to determine the most effective water and fertilizer management strategy for the growth and production of P. notoginseng. The assessment of yield, water and fertilizer productivity, and saponin content across all treatments revealed that the W3F3 treatment resulted in significant increases in the plant's height, stem diameter, and net photosynthetic rate. Meanwhile, the W2F3 treatment exhibited the best root morphological traits. The W3F4 treatment effectively increased dry matter and transpiration. The combination of water and fertilization had a coupling effect that not only increased yield to 1400 kg ha−1 but also improved water–fertilizer productivity. The application of the W2F3 treatment resulted in a significant increase in the accumulation of active components, leading to a total P. notoginseng saponin (PNS) content of 24.94%. Moreover, the comprehensive index obtained through the TOPSIS model indicated that the W2F3 treatment outperformed other treatments. Therefore, this treatment can be considered a promising water and fertilizer model for P. notoginseng cultivation, which can enhance its yield, quality, and productivity while promoting sustainable green development. [ABSTRACT FROM AUTHOR]

Panax notoginseng cultivation planting conditions are harsh and require high soil moisture and slope of cultivated land, plus it takes 3–7 years from planting to harvesting. At present, the continuous crop barrier of Panax notoginseng has not been solved, which makes the arable land suitable for planting significantly reduced. And yet, there is almost no report on the impact of coupling water and slope on the growth of Panax notoginseng. Therefore, this study aims to explore the effects of different irrigation levels and slopes on soil water content (SWC) in the root zone, soil nutrient content, root characteristics, yield, water use efficiency (WUE), partial fertilizer productivity (PFP) and economic benefits of Panax notoginseng. During 2018–2020, a field experiment was conducted in the Panax notoginseng growing seasons with three irrigation levels (I 1 : 70–75% θ FC , I 2 : 75–80% θ FC , I 3 : 80–85% θ FC) and three slopes (S 1 : 2.43°, S 2 : 6.38°, S 3 : 16.38°). The results evidenced that soil water and nutrient content increased with increasing irrigation and decreased with increasing slope. The yield of Panax notoginseng , root morphological characteristics, WUE, PFP, and economic benefits showed a trend of increasing first and then decreasing with the increase of irrigation amount and slope, which increased with the increase of planting years. These parameters reached their maximum at the irrigation I 2 (75–80% θ FC) and slope S 2 (6.38°) treatments. Thus, based on the results of this study, medium irrigation I 2 (75–80% θ FC) and slope S 2 (6.38°) should be considered as the best slope and water management strategy to obtain both high Panax notoginseng yield and economic benefits. Through establishing a multi-objective optimization model with binary quadratic regression analysis. It was indicated that Panax notoginseng yield, WUE, PFP, and economic benefits simultaneously reached ≥ 98% of their maximum values when irrigation interval was 152–193 mm and slope interval was 5.4–9°. In summary, the results obtained in this study have important practical significance for the water management of Panax notoginseng cultivation in slope farmland in Yunnan Province, China. [Display omitted] • Water regulation technology for Panax notoginseng cultivation on sloping land was proposed. • Soil nutrient content and Soil water content gradually decreases with increasing slope. • I 2 S 2 treatment obtain maximum yield and economic efficiency. • Irrigation interval of 152-193 mm and slope interval of 5.4-9° determined to make yield, economic benefits, PFP and WUE reach ≥ 98% maximum. [ABSTRACT FROM AUTHOR]