5 May 2015
a b s t r a c t
Phalaenopsis, an important pot plants worldwide, are propagated with a tissue culture technique. The aim
of the present study was to validate growth models for Phalaenopsis plantlets with measured data. Effect
of temperature and light irradiance on the growth characteristics was investigated by total weight, total
leaf area and weight ratio of shoot to root weight for Phalaenopsis Sogo Yukidian ‘V3’. Relationship between
culture days and total weight and leaf area of plantlets with was analyzed by nonlinear regression analysis.
A four-parameter logistics model for growth rate was selected used as the growth index for further study.
The relationships between environmental factors and the total weight, total leaf area of plantlets and the
weight ratio of leaf to root were evaluated by multiple regression analysis. These environmental factors
all had a significant effect on the growth characteristics. The optimal microclimate conditions for plantlets
culture of Phalaenopsis Sogo Yukidian ‘V3’ determined from the regression results were light irradiance
40–60 mol m−2 s−1, light temperature 29–32 ◦C and dark temperature 22–25 ◦C. The results can be useful
information for propagating Phalaenopsis plantlets.
© 2015 Elsevier B.V. All rights reserved
Table of contents
1. IntroductionIn 2014, 80 million units of orchids were produced in Taiwan.Most were Phalaenopsis. Commercial Phalaenopsis is propagatedfrom tissue culture. The quality and quantity of orchid plantletsneeds to be improved continuously.Orchid tissue culture plantlets are cultivated in a small asepticculture vessel. The air exchange between inside and outside air islimited because of the need to isolate microorganisms. Water andcomposition of the medium in the vessel are the main source ofnutrition. In the vessels, the aerial environment contains very highrelative humidity. From the investigation of the microclimate insidevessel, the CO2concentration is decreased in the light period andincreased in the dark period (Chen, 2007).The growth of plantlets inside vessels is affected by the internalmicroclimate, such as air temperature and humidity, light qual-ity and quantity (Hsu and Chen, 2009; George and Davies, 2008;Fujiwara and Kozai, 1995; Kozai, 2010). In the culture room, all∗Correspondence to: Department of Bio-industrial Mechatronics Engineering,National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan.Tel.: +886 4 22857562; fax: +886 4 22857135.E-mail address: email@example.com are placed on horizontal shelves. The practical way to con-trol the internal microclimate of the vessel is to modify the outsideenvironment of the culture room. Yao et al. (2007) proposed amodel to describe the microclimate inside a glass jar with medium.However, only a simulation result was presented. Models for airtemperature, relative humidity and photosynthetic photon flaxdensity (PPFD) was developed and validated with measured data(Chen, 2003, 2004, 2005).The effect of photosynthesis and other physiological activitieson plantlets is of interest. Pospisilova et al. (1997) mentioned irra-diance, CO2concentration, medium sucrose concentrations andgrowth regulators as factors. The highest net photosynthetic ratewas found with 25◦C and 226 mol m−2s−1light irradiance. Limet al. (1992) observed the effect of sugar, light intensity and CO2concentrations on the growth and mineral uptake of Dendrobiumplantlets. The nitrate uptake was increase with increased lightintensity, and CO2enrichment could not enhance the growth andion uptake. Yamagishi (1988) examined the effect of the culturetemperature on the growth characteristics of in vitro bulblets ofLilium japonicum Thunb and found that higher bulblets height andsugar uptake at 20◦C than 15◦C or 26◦C. Nguyen et al. (1999)observed the effect of different CO2concentrations and light inten-sities on the photosynthetic characteristics of coffee plantletsin vitro. Maximal dry mass, leaf area and photosynthetic rate were
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Date: 2015-05-26 17:37, source: Department of Bio-industrial Mechatronics Engineering,National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan