Effect of Humic Acid on Plant Growth, Nutrient Uptake, and Postharvest Life of Gerbera

Humic acid (HA) might benefit plant growth by improving nutrient uptake and hormonal effects. The effect of HA on growth, macroand micronutrient contents, and postharvest life of gerbera (Gerbera jamesonii L.) cv. 'Malibu' were examined. Different levels of humic acid (0, 100, 500, and 1000 mg/L) were applied to nutrient solution. Root growth increased at 1000 mg/L HA incorporated into the solution. Macro- and micronutrient contents of leaves and scapes including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) were significantly enhanced by HA. However, high levels of HA decreased some nutrient contents. Five-hundred mg/L HA increased the number of harvested flowers per plant (52%). Higher HA levels extended the vase life of harvested flowers by 23.66 days and could prevent and delay bent neck incidence. These postharvest responses were most probably due to Ca accumulation in scapes and hormone-like activity of HA.