Delonix regia pollen extract enhances growth and bioactive compound production in Coriandrum sativum by upregulating key biosynthetic genes

The application of biostimulants represents a sustainable strategy to enhance crop productivity and resilience. This study investigated the efficacy of Delonix regia pollen aqueous extract as a biostimulant on coriander ( Coriandrum sativum ). Seeds were primed with different concentrations of the extract (0%, 0.5%, 1%, and 1.5%) for 24–48 h. The 1% extract applied for 48 h was the most effective treatment, significantly increasing shoot fresh and dry weight, shoot length, and the content of total protein, phenolics, flavonoids, and terpenes. This treatment also led to a significant upregulation of the key biosynthetic genes Chalcone synthase (CHS) and geranylgeranyl pyrophosphate synthase (GGPS) by 1.4-fold and 2.1-fold, respectively. Principal component analysis confirmed a positive correlation among shoot fresh weight, total protein, terpene content, and GGPS expression. These findings demonstrate that D. regia pollen extract is a potent biostimulant that enhances coriander growth and the production of valuable bioactive compounds through the modulation of key metabolic pathways.