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Liquid Culture Systems for in vitro Plant Propagation

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232 T<strong>in</strong>o Hempfl<strong>in</strong>g & Walter Preil<br />

Netherlands, exceeded 64 million Euro <strong>in</strong> 2002. The <strong>in</strong>crease was 30.9 %<br />

compared to 2001 (Anonymous, 2003).<br />

In <strong>vitro</strong> culture procedures <strong>in</strong>clud<strong>in</strong>g 22 media <strong>for</strong>mulations <strong>for</strong><br />

Phalaenopsis were listed by Arditti and Ernst (1993), present<strong>in</strong>g an<br />

overview on the state of knowledge at that time. The application of standard<br />

protocols <strong>for</strong> micropropagation on solid medium on average results <strong>in</strong> a<br />

three-fold shoot multiplication rate after an eight-week subculture period.<br />

More recently, liquid systems <strong>in</strong>clud<strong>in</strong>g bioreactors or temporary immersion<br />

techniques were successfully applied giv<strong>in</strong>g rise to higher multiplication<br />

rates (Park et al., 1996, 2000; Samson et al., 2000).<br />

Most of agar gelled media <strong>for</strong> Phalaenopsis micropropagation are<br />

supplemented with BAP as cytok<strong>in</strong><strong>in</strong> source. A few publications stress the<br />

positive effects of TDZ on protocorm or adventitious bud regeneration<br />

(Ernst, 1994; Chen and Piluek, 1995; Chen et al., 2000). As far as we know,<br />

no experiments have been published on the effects of TDZ <strong>in</strong> liquid cultures<br />

of Phalaenopsis.<br />

The present study was carried out to <strong>in</strong>vestigate adventitious shoot<br />

multiplication and root<strong>in</strong>g <strong>in</strong> a temporary immersion system (TIS) us<strong>in</strong>g<br />

five-litre tw<strong>in</strong> glass vessels. The effects of medium substitution after two or<br />

four weeks were specifically determ<strong>in</strong>ed. Further, the <strong>in</strong>fluence of TDZexposure<br />

<strong>for</strong> 7 or 12 weeks on shoot size, multiplication rate and fresh<br />

weight was <strong>in</strong>vestigated. Dur<strong>in</strong>g the root<strong>in</strong>g phase various immersion<br />

frequencies were applied to determ<strong>in</strong>e optimum conditions.<br />

2. Material and methods<br />

2.1 Multiplication<br />

In <strong>vitro</strong> grown shoots of Phalaenopsis cv. Jaun<strong>in</strong>a (Breeder: Wolfgang<br />

Bock, Bremen, Germany) were used as <strong>in</strong>oculum. Per five-litre glass vessel<br />

70–72 shoots (1 – 3 cm length; total fresh weight: 20g) were <strong>in</strong>cubated. Each<br />

vessel was connected through a silicone tube with another vessel (Figure<br />

1 A) conta<strong>in</strong><strong>in</strong>g 2 litres of liquid MS-medium of ½ strength macro- and<br />

micro-elements (Murashige and Skoog, 1962), supplemented with 170 mg l -1<br />

NaH2PO4, 100 mg l -1 myo-<strong>in</strong>ositol, 0.5 mg l -1 nicot<strong>in</strong>ic acid, 0.5 mg l -1<br />

pyridox<strong>in</strong>e, 0.1 mg l -1 thiam<strong>in</strong>e HCl, 2.0 mg l -1 glyc<strong>in</strong>e, 1000 mg l -1 peptone<br />

and 20 g l -1 sucrose, as published by Chen et al. (2000). Additionally 0.5 mg<br />

l -1 thidiazuron (TDZ) was added.<br />

The liquid medium was dra<strong>in</strong>ed from the ‘medium-vessel’ <strong>in</strong>to the ‘plantvessel’<br />

and vice versa by means of compressed air be<strong>in</strong>g passed through a<br />

three-way solenoid valve controlled by a programmable timer as described

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