Augmenting photosynthesis, enzyme activities, nutrient content, yield and quality of Senna sophera (Cassia sophera L.) by P fertilization

In a pot experiment, the performance of senna sophera (a medicinal herb) was studied under five basal levels of phosphorus (0, 25, 50, 75 and 100 mg P kg⁻¹ soil). Physiological parameters were studied at 120, 150, 180 and 210 days after sowing (DAS). Application of 75 mg P kg⁻¹ soil treatment was the most beneficial and gave 20.4% higher photosynthetic rate at 150 DAS, 16.7% higher carbonic anhydrase activity and 15.6% higher nitrate reductase activity at 120 DAS, and 24.5% higher seed yield and 13.6% higher seed protein content at 210 DAS than the control (no phosphorus).