The effects of paclobutrazol and daminozide on in vitro micropropagation of some apple (Malus domestica) cultivars and M9-rootstock

Abstract

This study was carried out to determine the effects of PP 333 and Alar-85 containing 0.0, 0.5, 1.0, 2.5, and 5.0 ppm on the shoot image density, root image density, primer root number, rooting percentages, adventitious shoot numbers, shoot length and primer root length of apple rootstock-M9 and two apple cultivars (Starking Delicious and Amasya) in in vitro conditions. In vitro propagation of M9, Starking Delicious and Amasya was made on modified MS (Murashige and Skoog) medium supplemented with growth regulators either in a multiplication medium containing agar solidified MS basal composition and 0.5 ppm BAP with 0.1 ppm IBA, or in rooting medium: rotated liquid 1/2 MS and 0.5 ppm IAA, and PP 333 or Alar-85. Subculturing the shoots on modified MS medium supplemented with PP 333 (0.5 to 1.0 ppm) or Alar-85 (0.5 to 2.5 ppm) induced shoot image density, root image density, primer root number, rooting percentages, and adventitious shoot numbers while inhibiting the length of shoots and primer root, in every 5 weeks from a single shoot tip or adventitious bud, with best shoot extension and leaf growth. One ppm PP 333 and 2.5 ppm Alar-85 favoured the development of adventitious shoots or buds, and rooting in isolated internodes of the development shoots. Especially, it appears that rooting and adventitious shoot numbers of Starking Delicious and Amasya were more than M9. The PP 333 and Alar- 85 threshold values were low at < 1.0 and < 2.5 ppm, respectively. The thresholds of PP 333 at 1.0 ppm were 59.2% (Starking Delicious), 48.6% (Amasya) and 32.5% (M9), and thresholds of Alar-85 at 2.5 ppm were 50.4% (Starking Delicious), 41.3% (Amasya), and 35.7% (M9) for rooting percentages. The thresholds of the proliferation and rooting coefficients of M9 were significantly lower than those of other cultivars. M9 gave the poorest response to the treatments.

Key words: Malus spp., micropropagation, plant growth regulators, tissue culture.