Humic acid and folic acid application improve marketable traits of cut tuberose (Polianthes tuberosa)

Tuberose is an important cut flower in Iran and throughout the world. Since nutrition is of crucial significance for the growth, development, and quality of ornamental plants, the present study aimed to explore the effect of different levels of humic and folic acids on yield and quantitative and qualitative traits of tuberose (Polianthes tuberosa L.) based on a randomized complete block design with three replications in the Faculty of Agriculture, Agriculture and Natural Resources University of Gorgan, Iran in 2016. Humic and folic acids were applied at the rates of 0, 50, 100 or 150 mg L-1. The foliar application was performed in three phases, i.e. 30, 50 and 70 days after planting. The recorded traits included spike length, stem length and diameter, shoot fresh weight, floret number, leaf number and area, flower emergence time, bulblet number, root development depth, N, P and K content, vase life, and total chlorophyll. Analysis of variance showed that the application of humic acid significantly influenced all measured traits, except leaf number and flower emergence time. As humic acid rate was increased to 150 mg L-1, leaf total chlorophyll content was increased by 52 percent showing a significant difference with control. The foliar application of humic and folic acids increased N, P and K contents of leaves, and the strongest effect was observed at the rate of 150 mg L-1. The results lead us to the conclusion that the application of 150 mg L-1 humic acid and folic acid had the strongest impact on increasing the quantitative and qualitative traits of tuberose.