Effect of Water Soluble Fertilizers on Composition of Chlorophyll, Total phenols, IAA Oxidase Activity and Major Nutrients (N, P and K) in Dendrobium Orchid cv. Earsakul

An experiment was conducted at a private farm-M/s. Rynco Orchids, Perumchilambu village, Thuckalay, Kanyakumari District, Tamil Nadu (India) during 2012–2014 to evaluate the effect of five water soluble fertilizers at two different doses on composition of chlorophyll, total phenols, IAA oxidase activity, nitrogen, phosphorus and potassium present in Dendrobium orchid cv. Earsakul. Among the various fertilizers studied, application of 30: 10: 10 (0.4%) improved the chlorophyll a (0.72 mg/g), chlorophyll b (0.36 mg/g) and total chlorophyll content (1.07 mg/g) compared to control and other treatments. The total phenol content was highest (1.87 mg/g) in plants treated with 20: 20: 20 (0.2%) + mono potassium phosphate (0.2%) while IAA oxidase activity was the highest (0.85 mg of unoxidised auxin g⁻¹ hour⁻¹) in plants treated with T₈-20: 20: 20 (0.2%) + 13: 27: 27 (0.4%). The highest content of nitrogen (3.14%) was recorded in T₂-30: 10: 10 (0.4%) while that of phosphorus (0.47%) and potassium (4.57%) in 20: 20: 20 (0.2%) + 13: 27: 27 (0.4%).