Abstract: This study highlights the positive role of TRIA in inducing the somatic embryogenesis using secondary needles of mature trees of P. roxburghii. Very few reports of induction of somatic embryogenesis using secondary needles as explants are available in conifers. Secondary needles of mature pines can be used as the best explant-source-material for the micropropagation of conifers. Explants cold-pretreated at 4°C and incubated for 3 days on 0.3% activated charcoal induced white-mucilaginous embryogenic tissue on DCR basal medium (initiation medium-I ) supplemented with 22.62 μM 2, 4-D, 26.85 μM NAA and 5 μM TRIA in all the 3 genotypes (PR17, PR100 and PR321) of Pinus roxburghii. Explants without cold pre-treatment induced non-embryogenic tissue on initiation medium supplemented with various concentrations of TRIA. Therefore, both the cold pre-treatment and the presence of TRIA in the initiation medium might have triggered the cells in programming towards the somatic embryogenesis. It was concluded that combination of stress induction by cold pre-treatment and inclusion of TRIA with DCR basal medium has a great potential of inducing embryogenic tissue in all the three genotypes tested. This has created a new possibility of micropropagation of pines for the current demands of commercial forestry.