Humic Acid-mediated Resistance in Cotton (Gossypium hirsutum L.) against Bollworm (Helicoverpa armigera)

Cotton (Gossypium) is a globally important fiber crop.Cotton bollworm (Helicoverpa armigera) attacks on the boll and interrupted its growth and productivity.Recently, several studies have proven the ability of humic acid (HA), an organic compound obtained from soil humus to improve plant growth and responses against biotic stress.This study evaluates the effects of humic acid on cotton seed germination and callus formation for enhanced bollworm resistance.It is hypothesized that humic acid treatment promotes plant growth, enhances callus induction, and increases resistance to cotton bollworm.The methodology involved the collection of cotton seeds and were surface sterilized.The seeds were germinated on Murashige-and-Skoog's (MS) medium.Grown embryos were transferred to culture tubes and maintained on MS medium with auxin or cytokinin for callus induction.During callus induction and maintenance, humic acid was supplemented in three concentrations: 0.1%, 0.5% or 1%.Growth parameters along with biomass were measured and the efficacy of humic acid on enhancing pest resistance was tested through bioassays against Helicoverpa armigera larvae.The findings of the study revealed that humic acid appreciably influenced callus induction.The growth and acclimatization of plants treated with humic acid were significantly higher than untreated control plants.The percentage of death rate on the cotton bollworm in humic acid-treated plants were 60%, compared to untreated plants resulted in the increased resistance against these pests.Hence, this study concluded that humic acid accelerated the growth of cotton, promoted callus induction and increased resistance to cotton bollworm.