Evaluation of seedling low phosphorus tolerance of main Brassica napus varieties in Yunnan region

To evaluate the low-phosphorus tolerance of the main cultivated rapeseed (Brassica napus L.) in Yunnan, screen for locally adapted low-phosphorus-tolerant germplasm, and analyze the correlations among various low-phosphorus tolerance traits, this study assessed the performance of major Yunnan rapeseed varieties under low-phosphorus conditions using nutrient solution culture at the seedling stage. The results showed that low-phosphorus treatment significantly reduced most agronomic traits, including shoot fresh weight (FWS), root fresh weight (FWR), shoot dry weight (DWS), root dry weight (DWR), and phosphorus uptake efficiency (PUpE). These traits exhibited substantial genetic variation among the tested varieties. Correlation analysis revealed significant positive relationships (P < 0.01) among shoot length (SL), root length (RL), FWS, FWR, leaf area (LA), DWS, DWR, and PUpE under both treatment conditions. Based on a comprehensive scoring system for low-phosphorus tolerance, the 59 varieties were classified into four categories: extremely sensitive (1 variety), sensitive (27 varieties), tolerant (26 varieties), and extremely tolerant (5 varieties). Among them, YF 21 and YF 32 were identified as low-phosphorus-tolerant varieties, while YF 01 and YF 43 were identified as low-phosphorus-sensitive varieties. This study provides valuable resources and a scientific basis for further screening and utilization of low-phosphorus-tolerant rapeseed germplasm.