Plantlet regeneration from fascicular buds on seedling explants of Pinus roxburghii

Abstract

Shoot apices of Pinus roxburghii Sarg were cultured on Murashige and Skoog’s medium (MS) supplemented with cytokinins [6 - benzyladenine (BA), kinetin and N - benzyl - 9 - (2 - tetrahydropyranyl) adenine (BPA)] alone and in combination with auxin, α - napthaleneacetic acid (NAA). Of the three cytokinins tested at varying concentrations, medium supplemented with 10 µM BA was found optimal in respect of explant responsiveness (97.22 %) and average number of buds induced per explant (7.42). The concentration of cytokinins in the induction medium had a profound effect on rate of elongation of induced buds on MS basal medium containing 0.5 % activated charcoal. Further, shoots induced on lower concentrations of BA increased up to 2.4 times in length in 4 weeks. Decapitation of the explant enhanced the rate of axillary bud elongation. Proliferating shoot cultures were established by sub - culturing the axillary shoots on MS supplemented with 10 µM BA. Shoots 2–3 cm in length were suitable for culturing as more buds were induced on them compared to longer or shorter shoots. Root primordia were induced on 70.83 % shoots when transferred to 1/2 MS medium supplemented with 5.0 µM NAA. Elongation of root primordia (60 %) was achieved in liquid 1/2 MS basal medium. The plantlets were successfully transferred to soil after hardening; the time period from initiation of shoot buds to transplantation being 20–22 weeks.