Propagation of Ornamental Plants
5(4): 179-185, 2005
GROWTH PROMOTION OF GERBERA PLANTLETS IN LARGE VESSELS BY USING PHOTOAUTOTROPHIC MICROPROPAGATION SYSTEM WITH FORCED VENTILATION
Yulan Xiao¹²*, Landi He¹ Tao Liu¹ and Yuhua Yang¹
¹Institute of Environmental Science, Kunming, Yunnan 650032, China, *E-mail: firstname.lastname@example.org
²Current address: Laboratory of Environmental Control Engineering, Faculty of Horticulture, Chiba University, Matsudo, Chiba 271-8510 Japan, *Fax: +86-871-4146530
Gerberas (Gerbera jamesonii L.) are commercially propagated by tissue culture. However, slow growth, poor rooting, physiological and morphological disorders, and microbial contamination in vitro, as well as low survival ex vitro are commonly observed in conventional or photomixotrophic micropropagation (PM) systems using sugar-containing media and small vessels with restricted natural ventilation. To solve these problems, a photoautotrophic micropropagation (PA) system using sugar-free media and large vessels (volume =120 l) with forced ventilation has been developed and applied for commercial production of gerbera plantlets. The major goal of the PA system is to produce a large number of high-quality plantlets with less space, simplified operation, and high productivity. The design of the PA system included a forced ventilation unit for supplying CO2-enriched, humidified, and cooled air to control the CO2 concentration at 1500 μmol mol-1, relative humidity from 100% to 80%, decreasing with culture days, and air temperature at 23 ± 1ºC in the large vessel. Growth of the plantlets in the PA system was compared with that in the PM system. The number of leaves, the leaf area, and the shoot and root dry weight were, respectively, 1.7, 5.2, 4.6, and 3.8 times greater in plantlets grown using the PA system than those in plantlets grown using the PM system. The net photosynthetic rate and chlorophyll concentration of the PA-grown plantlets were, respectively, 9.2 and 2.2 times greater than those of the PM-grown plantlets. Rooting percentage in vitro and survival percentage ex vitro were, respectively, 98% and 95% among the PA-grown plantlets, and 62% and 57% among the PM-grown plantlets. The total productivity of the PA system was 6.9 times higher than that of the PM system. In the present study it is shown that the PA system has advantages over the PM system for commercial application with respect to enhanced growth and high productivity.
Key words: chlorophyll concentration, CO2 enrichment, net photosynthetic rate, sugar-free medium, survival percentage.