An innovative vegetable-flower-oil canola ( Brassica napus ) cropping system increases crop yields and economic returns, while reducing environmental impact in the Erhai Lake Basin

The Erhai Lake Basin is subject to severe eutrophication from agricultural nutrient losses, and current canola farming in the region fails to balance environmental protection, yield and economic benefits. To address the central challenge of reconciling green production with high-value output, an innovative vegetable-flower-oil canola system was developed. A field experiment evaluated five canola cropping systems: control (CK), conventional organic (CO), organic optimization (OR), green production (GR) and ecological (EC). Key indicators for assessing green production and economic performance including yields, floral traits, N, P and irrigation water use efficiencies (NUE, PUE and IWUE, respectively), soil N and P surpluses, and economic performance were measured. The entropy-weighted TOPSIS model enabled objective multi-criteria evaluation. Results ranked systems by relative closeness (Ci): EC exhibited the highest Ci (0.50–0.75), with the full ranking: EC > GR > OR > CO. EC significantly outperformed CO: it increased net benefit by 42.7 thousand yuan·ha–1, reduced soil N and P surpluses (54.1%–57.2% and 81.6%–84.0%, respectively), improved NUE (62.7%–112%) and PUE (306%–392%), enhanced IWUE by 181.50%, and boosted yields. EC enhanced floral traits (138%–342% more flowers, 3–10 days longer flowering), supporting agritourism. The EC system meets the dual goals of green production and high-value output while offering agritourism value, providing sustainable solutions for agricultural green development in vulnerable lake basins.