Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Effects of sustained subculture on apparent rejuvenation of the apple rootstock in vitro and in vivo. | 187s Ann. Sci. For. 1989 46 suppl. 187S-189S Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Effects of sustained subculture on apparent rejuvenation of the apple rootstock in vitro and in vivo . Webster and . Jones Institute of Horticultural Research East Mailing Maidstone Kent . Introduction Sequential subculture of fruit trees leads to a gradual physiological change which may be termed rejuvenation This change is characterized by a gradual improvement in shoot production and rooting in vitro Jones 1985 . Hedges established from micropropagated plants of the plum rootstock Pixy Prunes insititia continued for at least 9 yr to produce shoot cuttings with the juvenile character of more rapid rooting Howard et al. 1989a . Thus rejuvenation as a result of micropropagation may be exploited to improve conventional propagation of clones which are normally difficult to propagate. This paper describes the apparent rejuvenation in vitro of the apple rootstock and the subsequent retention of juvenile characters in micropropagated plants in the field. is one of the most frequently used apple rootstocks worldwide but suffers from the serious shortcoming of being difficult to propagate. Materials and Methods Two shoot culture lines A and B were established in 1986 from 2 shoot tip explants on MS proliferation medium containing 2 mg l BAP benzylaminopurine mg l IBA indole butyric acid and 162 mg l phloroglucinol PG . These 2 culture lines were subcultured monthly for 21 mo along with 2 other culture lines initiated in 1978 and 1982 respectively In vitro rooting involved transfer for 4 d of single shoots from proliferation medium to MS medium containing 3 mg I IBA followed by transfer for 3 wk to half-strength MS medium without growth regulators. Direct rooting involved transfer of single shoots from proliferation medium dipped in a powder preparation of I BA 10 Captan to sterile horticultural sand for 4 wk Webster and Jones 1989 . .
