Manju Modgil and N Prabha Negi
An efficient and reliable procedure for rooting and hardening of in vitro raised shoots of apple rootstock, Merton 793 has been developed. 66.78% rooting was obtained with 1/2 MS medium supplemented with 0.1 mg/l NAA but the roots were thick and with profuse callus. 0.2% activated charcoal was used to suppress the callus but rooting efficiency reduced. Successful rooting was related to exposure of shoots to NAA supplemented liquid medium for few days and transferred to solid medium without NAA. Reduction of MS salts (1/3 and ) and sucrose (20 and 15 g/l) in root elongation medium showed decreased rooting in comparison to MS with 25 g/l sucrose. Among various substrates tested, agar was found the best among sand, perlite and tapi - oca pearls. There was no rooting in sand and perlite while, less rooting in tapioca pearls. Rooted plantlets of about 2-3 cm height were subsequently transferred to peat-sand for hardening. 70% plantlets established when roots were induced without callus. On the other hand, 80% of the plantlets established successfully when partial in vitro root initiation was carried out in liquid medium and ex vitro root elongation and hardening in peat-sand. For direct rooting, around 55% plant establishment was observed when shoots were dipped for 10 mins in higher concentration of NAA solution and planted in portrays containing peat-sand mixture. Partial in vitro rooting or direct rooting of shoots of M793 may be recommended for commercial propagation programme.
Manju Modgil has completed his Ph.D at the age of 28 years from Himachal Pradesh University. She is Associate Professor (Biotechnology), Dr Y S Parmar university of horticulture and forestry ,Solan (HP) and working mainly on apple tissue culture. She has published more than 32 research papers in reputed journals and 4 book chapters.