IMPACT OF SALICYLIC ACID AND HUMIC ACID ON GROWTH AND QUALITY OF CUT IRIS (Iris × Hollandica)

Abstract

Iris (Iris × hollandica), a prominent species within the Iridaceae family, is widely recognized for its ornamental value and extensive range of flower colors. The Dutch Iris, in particular, holds significant commercial value due to its striking flowers with three distinct petals, making it a profitable crop for floriculture. Iris has been cultivated for ornamental purposes globally and is native to the Northern Hemisphere, with over 299 species documented. Iris flowers, including those found in northern Pakistan, are utilized in perfumes, cosmetics, and traditional medicine.
This study, conducted at the Horticulture Field Area of the National Agriculture Center in Islamabad during the 2020–2021 growing season, aimed to assess the effects of humic acid and salicylic acid on the growth and quality of Iris (Iris × hollandica). Six different concentrations of humic acid and salicylic acid were applied in a randomized complete block design (RCBD), consisting of six treatments (one control and five experimental treatments) with three biological replications. Parameters assessed included plant height, number of leaves, flowering time, stem diameter, spike length, flower count per plant, leaf length, bulb count per plant, bulb weight, bulb size, proline content, and vase life. The results revealed that treatment with salicylic acid and humic acid at a concentration of 0.75 mg/L resulted in significant improvements in key growth and quality parameters. Specifically, this treatment increased plant height (55.27cm), flower number by (2.88) and bulb weight by (30.44g) notably it also enhanced the vase life of the flowers by (10 days), which is critical for post-harvest quality. Among the tested concentrations (ranging from 0.25mg/L to 0.75 mg/L), 0.75 mg/L was found to be most effective in enhancing growth and quality parameters. Statistical analysis indicated that these results were significant at (0.05). These findings suggest that the combined application of salicylic acid and humic acid at this concentration can be an effective strategy to enhance both vegetative and reproductive growth, as well as the marketability of Iris flowers. The outcomes of this research provide valuable insights for improving the quality and yield of Iris production in commercial floriculture.