Effects of plant growth regulators and environmental factors on in vitro propagation of x Malosorbus florentina.

摘要

Aim of the work was to improve the micropropagation protocol of the rare and endangered x Malosorbus florentina enabling its conservation and introduction as an ornamental plant. The micropropagation of the species is difficult at the establishment and rooting phase. Using of thidiazuron (TDZ) instead of BA or zeatin at the culture initiation phase almost doubled the establishment percentage of the explants. The shoots produced on a TDZ-supplemented MS medium were short, but following subculture on a MS medium supplemented with 1 mg l-1 BA+0.1 mg l-1 IBA explants from TDZ-medium surpassed those from BA- or zeatin-medium in shoot number without falling short in shoot length. BA at 1-2 mg l-1 proved superior to zeatin, kinetin, and 2iP in multiplication. Darkness during the root induction phase (one week on auxin supplemented half-strength MS medium) did not improve rooting and stimulated excessive callus formation. Activated charcoal (AC) enhanced rooting of juvenile origin microshoots when added into the medium during the first week of the root expression phase (four weeks on hormone free half-strength MS medium). Microshoots produced on a medium with low cytokinin concentration or on a BA-medium rooted at higher percentages than those produced on a high-cytokinin medium or on a zeatin- or 2iP-medium. Higher rooting percentage (65%) was induced on half-strength MS medium with 4 or 8 mg l-1 IAA. Higher acclimatization percentages and faster growth were achieved when plantlets with well developed roots were transferred ex vitro on a peat-perlite (1:1, v/v) mixture in early spring.