Effect of Soil-Applied NPK and Foliar Nutrition on Leaf N, P and K Uptake of Senna (Cassia angustifolia Vahl.)

Abstract

A field experiment was conducted at the Herbal Garden, college of Agriculture, UAS, Raichurto study the response of senna (Cassia angustifolia Vahl.) to varying soil-applied NPK levels and foliar nutrition with respect to leaf nitrogen, phosphorus and potassium uptake at harvest. The experiment was laid out in a factorial randomized block design comprising four levels of soil-applied NPK [F1: 125% RDF, F2: 100% RDF, F3: 75% RDF and F4: control (no RDF)] and four foliar spray treatments [M1: 1% urea, M2: 1% 19:19:19, M3: seaweed extract and M4: water spray]. The results revealed that nutrient uptake was significantly influenced by both soil and foliar nutrition. Among the fertilizer levels, 125% RDF (F1) recorded the highest uptake of nitrogen (74.78 kg ha⁻¹), phosphorus (50.08 kg ha⁻¹) and potassium (13.98 kg ha⁻¹), while the control (F4) recorded the lowest values. Among foliar treatments, seaweed extract spray (M3) showed the maximum N, P and K uptake. The interaction effect was significant, and the combined treatment F1M3 (125% RDF + seaweed extract) recorded the highest uptake of all three nutrients. Regression analysis indicated a strong positive linear relationship between increasing NPK levels and nutrient uptake. The percent increase in nutrient uptake under F1 over control was 128.1% for N, 197.2% for P and 85.7% for K, while F1M3 over F4M4 showed increases of 416.4%, 339.7% and 175.0%, respectively. The study concludes that application of 125% RDF along with seaweed extract foliar spray is the most effective nutrient management strategy for maximizing nutrient uptake in senna leaves at harvest.