The effect of sucrose concentrations and different types of tube cap on in vitro growth of Dahlia (Dahlia sp.) using vermiculite as substrate

Dahlia sp. is an ornamental plant belongs to Compositae. Plantlets produced through conventional in vitro culture have low growth ability during acclimatization. The use of ventilation on in vitro culture is expected to affect the condition of the plantlet micro environment. Reducing sucrose concentration will improve the physiological functions of the plant. This study aimed to investigate the effect of reduction of sucrose concentrations and the use of various culture tube caps on the growth of shoots cultures of Dahlia sp. The experiments used was factorial completely randomized design with two factors ie. concentrations of sucrose (10, 20, and 30 g/l) in combination with four different type of tube caps (Al foil, transparent plastic, filter 1 cm and 2 cm). The experiments used vermiculite as substrate and MS medium with 9 replicates. Parameters observed were plant height, number of leaves, number of nodes, and number of roots which observed every week up to 8 weeks of culture. At 8 weeks culture, fresh weight, and dry weight were also recorded. The results showed that reducing sucrose concentration in combination with tube cap significantly affected on the growth of shoot height, number of leaves, nodes and roots as well as length of root. The highest Dahlia shoot was found in the media containing 10 g/l sucrose in tubes with plastic cap and in 20 g/l sucrose with 2 cm filter cap. The highest number of leaves and nodes was found in media containing 30g/l of sucrose using Al foil and 1 cm filter caps, both were significantly different with others. The highest fresh weight was found in MS medium containing 30 g/l of sucrose with 1 cm filter caps. Highest number of roots were found in the 10 g/l of sucrose using 1cm filter cap and in 30 g/l sucrose with a plastic cap.