Humic acid improves morpho-physiological and biochemical traits of Phyla nodiflora

Phyla nodiflora faces a retarded growth during the first growing season; therefore, this study was focused on the evaluation of the effect of humic acid on the growth and establishment of P. nodiflora. Herein, the first experiment was performed to assay the effect of four levels of humic acid, including 0, 250, 500, and 750 mg L-1, on the rooting properties of P. nodiflora in the sand medium. The second and third experiments were performed to evaluate the influence of humic acid on the morpho-physiological characteristics in the greenhouse and field environments with two humic acid foliar and fertigation applications, in two consecutive years. The physiological traits including chlorophyll, carotenoids, carbohydrates, protein, and anthocyanin content along with the morphological traits including underground organs (root length and volume, root wet and dry weight) and aerial organs (wet and dry weight) were significantly enhanced by humic acid in both application methods at the three experiments when compared to the control. Fertigation with humic acid of 500 mg L-1 in the field and greenhouse conditions was the most effective treatment on the traits measured. Fertigation with humic acid of 500 mg L-1 can be used to accelerate the growth rate of P. nodiflora during the first growing season.