EFFECT OF IRRADIANCE LEVEL DURING IN VITRO PROPAGATION OF ARISTOLOCHIA MANCHURIENSIS

Abstract

The ornamental plant Aristolochia manchuriensis is a liana with large heart-shaped leaves. It is difficult to propagate by cuttings and therefore a propagation method in vitro has been developed. The basic medium for multiplication was that of Murashige and Skoog (1962), supplemented with 6-benzylaminopurine, 0.4 mg l -1 . During multiplication the following photosynthetic photon flux (PPF) levels were tested; 20, 40, 60, and 80 pmol m -2 s -1 Effects of PPF levels on multiplication stabilized after three subcultures (84 d); the PPF level 20 pmol m -2 s -1* resulted in the lowest multiplication rate (MR) per month (3.0), and 80 pmol m -2 s -1 in the highest MR per month (4.2). PPF level during multiplication also affected the subsequent rooting. The maximum percentage of rooted shoots was attained after a PPF level of 80 μmol-m -2 s -1 during multiplication. A prolonged period on the last multiplication medium before rooting (6 weeks instead of 4 weeks) increased the multiplication rate significantly but affected subsequent rooting negatively, which dropped from 41 % to 12 %. Darkness during the first days (1 d or 7 d) on the rooting medium, improved the percentage of rooted shoots. It was also beneficial to split the base of the shoot prior to rooting.