This research was conducted at Agriculture Faculty Nursery at
Mansoura University, during the two seasons of 2022/2023. In order to
study the effect of humic acid (HA) and arbuscular mycorrhizal fungi
(AMF) and their interactions on vegetative growth, essential oil and
chemical composition of Thymus vulgais. Plants were irrigated with (HA)
as bio-stimulant applied monthly at the concentrations of (0, 0.5, 1 and 2%)
grown in pots containing both sandy soil with or without (AMF). The
results showed that added (AMF) to the soil led to significantly increase in
the studied traits such as, growth parameter, yield, chlorophyll content,
total carbohydrates and essential oil percentage. Specifically, (AMF)
combined with (HA) at 1% resulted in a significant increase in fresh weight
(16-46%), chlorophyll a (84%), carbohydrate (4-32%), and oil yield (75-
80%) as compered with (AMF) without humic acid. Furthermore, the
application of (HA) at 1% also influenced the composition of thymus oil.
The results cited above concluded that (AMF) and humic acid increase
both growth and essential oil production in plants which enhanced its
commercial value.