Differential role of endogenous hormones and effect of exogenous hormonal-temperature treatments on seed dormancy and germination in Heeng (F. assa-foetida L.) and its wild relative F. jaeschkeana Vatke

Abstract

Ferula assa-foetida L., a herbaceous perennial plant usually found in temperate regions, exhibits persistent dormancy when grown under ambient conditions. To address this, the present study investigated the role of endogenous and exogenous hormones in the germination of F. assa-foetida L. and its wild relative F. jaeschkeana Vatke. Comparative endogenous hormonal changes were analyzed at different periods of seed germination in both species using ultra-high performance quadrupole time of flight mass spectrometry/ mass spectrometry (UHPLC-MS). For exogenous treatments, seeds of both species were treated with three hormones viz, gibberellic acid (GA₃), 6-benzylaminopurine (BAP) and kinetin (KIN) at three different concentrations (50, 100, and 150 ppm) and two temperatures conditions (4 °C and 25 °C) to break seed dormancy. Results showed that there was a significant abrupt change in the content of the hormones during germination. The concentration of GA₃, indole-3-acetic acid (IAA), and jasmonic acid (JA) reduced successively in both species from the dry seed stage till seedling emergence while abscisic acid (ABA) content increased significantly in imbibed seeds up to seedling emergence in F. assa-foetida L. Besides, treatment of seeds with exogenous GA₃, BAP, and KIN in both species exhibited a significant increase in germination percentage at 4 °C than 25 °C. Chilling treatment along with 50 ppm GA₃ hormone treatment increased the seed germination up to 94% and 78% in F. assa-foetida L. and F. jaeschkeana Vatke, respectively. Hence, this study suggests that GA₃ can be used to boost overall seed germination, accelerate seedling development, and overcome seed dormancy in both Ferula species. Future investigations should focus on elucidating the molecular mechanisms underlying hormonal regulation during seed dormancy and germination in both species while optimizing synergistic hormonal treatments to accelerate germination and support its large-scale cultivation worldwide.