Abstract The present study investigated the dynamics of nutrient utilization and various growth and physiological parameters during in vitro proliferation of apple root stock ‘M9 EMLA’ in two different bioreactor systems, i.e. temporary and continuous immersions. Indi- vidual shoots obtained from temporary immer- sion system had higher dry mass and were of better quality than those obtained from continuous immersion. In continuous immersion bioreactor, apple shoots appeared to utilize more nutrients from liquid culture medium than that from temporary immersion. The shoot growth was limited by the availability of phosphate and nitrogen in continuous immer- sion system. The shoots produced in temporary immersion bioreactor showed higher photosyn- thetic rate, maximum quantum yield of photo- system-II and slow but steady rate of nutrient absorption, indicating the occurrence of higher photomixotrophic metabolism. The study also showed that high level of antioxidant scavenging enzymes in shoots grown in continuous immer- sion system induced physiological changes to foster adaptation to stresses. Keywords Antioxidant enzymes Æ Apple Æ Bioreactor Æ Continuous immersion system Æ F v /F m Æ Nutrient utilization Æ Temporary immersion system Abbreviations APX Ascorbate peroxidase BTBB Balloon-type bubble bioreactor BA N 6 -benzyladenine CAT Catalase IBA Indole-3-butyric acid G-POD Guaiacol peroxidase GA 3 Gibberellic acid GR Glutathione reductase MS Murashige and Skoog’s (1962) medium PPFD Photosynthetic photon flux density ROS Reactive oxygen species SOD Superoxide dismutase D. Chakrabarty Æ S. K. Datta Floriculture Section, National Botanical Research Institute, Lucknow 226001, India Y. H. Dewir Department of Horticulture, Faculty of Agriculture, Kafr El Sheikh University, Kafr El Sheikh 33516, Egypt D. Chakrabarty Æ Y. H. Dewir Æ E. J. Hahn Æ K. Y. Paek (&) Research Center for the Development of Advanced Horticultural Technology, Chungbuk National University, Cheong-ju 361-763, Korea e-mail: paekky@chungbuk.ac.kr Plant Growth Regul (2007) 51:11–19 DOI 10.1007/s10725-006-9115-5 123 ORIGINAL PAPER The dynamics of nutrient utilization and growth of apple root stock ‘M9 EMLA’ in temporary versus continuous immersion bioreactors D. Chakrabarty Æ Y. H. Dewir Æ E. J. Hahn Æ S. K. Datta Æ K. Y. Paek Received: 31 May 2006 / Accepted: 31 August 2006 / Published online: 6 December 2006 Ó Springer Science+Business Media B.V. 2006