Effects of Farmyard Manure, NPK Levels, and Foliar Nutrition on Chemical and Biochemical Parameters of True Indigo (Indigofera tinctoria L.)

The use of plants as natural dyes in the textile industry has gained significant attention in recent years. Indigofera tinctoria L., a member of the Fabaceae family native to India, has emerged as a promising sustainable dye source. Beyond its applications in textiles, I. tinctoria also holds significance in herbal medicine, highlighting its multifaceted utility. A two-year field experiment (2022 and 2023) in split-split plot design was conducted at the College of Agriculture, Vellanikkara, Kerala Agricultural University, to investigate the effects of farmyard manure (FYM) [5, 7.5, and 10 t ha-1], NPK levels [10:10:20, 20:10:40, 30:10:60, and 40:10:80 kg ha-1], and foliar nutrition [water spray, nano urea 0.4%, and seaweed extract 0.4%] on the indican content and nutrient content of indigo plants. The results showed that FYM [10 t ha-1] increased the indican content [by 8.73%], nitrogen [by 11.02%], phosphorus [by 9.9%], and potassium [by 11.27%]. NPK levels [30:10:60 kg ha-1 and 40:10:80 kg ha-1] showed similar effects on indican and nutrient content. Foliar application of seaweed extract [0.4%] increased indican and phosphorus content. The interaction between FYM, NPK levels, and foliar nutrition significantly affected the indican, nitrogen, and potassium contents. The study suggests that integrated use of FYM [10 t ha-1], NPK [30:10:60 kg ha-1], and foliar nutrition with seaweed extract [0.4%] can improve plant chemical and biochemical parameters.