Effect of Humic Acid Application Methods on Growth, Flowering, and Yield of African Marigold (Tagetes erecta L.) cv. Pusa Narangi Gainda

Abstract

African marigold (Tagetes erecta L.) is a popular loose flower crop in India, widely used for making garlands, religious offerings, and landscape decoration. Its growth and flower quality depend heavily on integrated nutrient management, but excessive reliance on chemical fertilizers has raised concerns about soil health and sustainability. To explore alternatives, a field experiment was conducted on African marigold cv. Pusa Narangi Gainda at the Floriculture Research Center (FRC), Department of Floriculture and Landscaping, College of Horticulture, Sardar Vallabhbhai Patel University of Agriculture and Technology (SVPUA&T), Meerut, India. The experiment followed a randomized block design with three replications and thirteen treatments, including one with 100% recommended dose of fertilizer (RDF) and the rest with 75% RDF. Under 75% RDF, humic acid was applied through soil drenching, foliar spray, or their combination at four concentrations (0.2%, 0.4%, 0.6%, and 0.8%) applied 3 times at 20-days intervals after transplanting. Application of 75% RDF + 0.6% humic acid (HA) by soil drenching (SD)+ 0.6% HA by foliar spray at 20, 40, and 60 days at treatment (DAT) was effective in increasing vegetative growth and flower yield parameters such as plant height, stem thickness, plant spread, number of primary branches per plant, minimum days to bud initiation, days taken to first flower opening, and 50% flowering, longest flowering duration, size of flower, number of flowers per plant, flower yield (g), and seed yield (g) per plant. The findings indicate that integrating chemical fertilizers with humic acid enhances growth, yield, and sustainability in African marigold production.