Effect of different nitrogen nutrition on growth, yield and quality of Senna tora in northern Vietnam

Background and Objective: Senna tora is a valuable medicinal plant and an important natural source of aurantioobtusin, a compound with strong anti-inflammatory activity. However, knowledge of how nitrogen (N) nutrition influences its growth, seed yield and pharmaceutical quality is limited. This study aimed to determine the optimal N application rate for maximizing both seed yield and aurantioobtusin content in S. tora. Materials and Methods: A field experiment was conducted in Thanh Tri (Hanoi, Vietnam) using six N application rates: N0 (0 kg/ha), N1 (35 kg/ha), N2 (70 kg/ha), N3 (105 kg/ha), N4 (140 kg/ha) and N5 (175 kg/ha). Plant growth, seed yield and aurantioobtusin content were measured at harvest. Statistical analysis was performed using CropStat 7.2, Microsoft Excel 2016 and RStudio, with treatment effects tested at p<0.05 and regression used to evaluate relationships between N rates and measured parameter. Results: Plants receiving N3 (105 kg/ha) exhibited the highest growth performance, with a seed yield of 2.02 t/ha and aurantioobtusin content of 0.24%. While higher N rates increased foliage biomass, they significantly reduced seed yield (p<0.05). The N3 treatment effectively balanced both seed productivity and medicinal quality. Conclusion: Application of 105 kg/ha N optimizes seed yield and aurantioobtusin content in S. tora, providing practical guidance for sustainable cultivation and medicinal compound production. Excessive N application increases vegetative growth but compromises seed yield, highlighting the need for balanced nutrient management. Future studies could explore long-term environmental impacts and interactions with other nutrients.