Effects of Coconut Milk, Agar, and Sucrose Concentrations, and Media pH on the Proliferation of Cymbidium Protocorm-like Bodies Cultured in vitro

Abstract

Shoot apexes were aseptically excised out of the mother Cymbidium plant and preliminarily cultured with Knudson′s C medium. The Protocorms formed on the cultures were cut into pieces of appropriate size and the cut pieces were subcultured 12 times. At each time, cutting and selection of pieces were made to assure the cultures of uniform quality from the morphological and physiological viewpoints. After the preliminary subculture, the cultures obtained were excised again to prepare uniform propagules of 1.5mm in size. The propagules were cultured in vitro with tentative media which were supplemented with coconut milk, agar, or sucrose, and otherwise adjusted to differential pH values.
(1) In the Knudson′s C basal solution containing 15g/l agar, protocorms proliferated best when 10 to 25% coconut milk was added; and highest increase in fresh weight was attained when 10% coconut milk was added.
(2) On the solid culture medium, protocorms proliferated best in the lots of 0.8 and 1.2% agar, and highest increase was obtained in the lot of 1.2% agar.
(3) In both Knudson′s C and Kyoto solutions, the addition of 2% sucrose caused highest increases in fresh weight. As a basal medium, Kyoto solution seemed somewhat better than Knudson′s C solution.
(4) Increase in fresh weight was highest at pH 5.0 and 5.5 in Kyoto solution.
(5) It can be inferred that there are appreciable differences between preferable culture conditions for both protocorm proliferation and formation of shoot and root primordia in the protocorm.