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Liquid Culture Systems for in vitro Plant Propagation

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Chapter 15<br />

Application of a temporary immersion system <strong>in</strong> mass<br />

propagation of Phalaenopsis<br />

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

Institute <strong>for</strong> Ornamental <strong>Plant</strong> Breed<strong>in</strong>g, Bornkampsweg 31, D – 22926 Ahrensburg,<br />

Germany. E-mail: w.preil@bafz.de<br />

Abstract: A temporary immersion system consist<strong>in</strong>g of a series of five-litre tw<strong>in</strong> glass<br />

vessels was successfully used <strong>for</strong> <strong>in</strong> <strong>vitro</strong> adventitious shoot multiplication and root<strong>in</strong>g of<br />

Phalaenopsis. Highest shoot multiplication rate of 25.4 was achieved after twelve weeks<br />

when eight immersions per day, of ten m<strong>in</strong>utes each, were used. Fresh medium conta<strong>in</strong><strong>in</strong>g<br />

0.5 mg l -1 TDZ was supplemented every two weeks. The different periods of TDZ exposure<br />

affect the multiplication rate, fresh weight rate and shoot size. Seven-week culture on TDZconta<strong>in</strong><strong>in</strong>g<br />

medium, followed by five weeks on TDZ-free medium, resulted <strong>in</strong> 18 % of shoots<br />

smaller than 1 cm, 56 % were of 1-3 cm and 26 % exceeded 3 cm <strong>in</strong> length, respectively.<br />

Small shoots are suitable as <strong>in</strong>oculum <strong>for</strong> the next multiplication cycle, whereas shoots larger<br />

than 1 cm can be rooted on cytok<strong>in</strong><strong>in</strong>-free medium. Highest percentage of rooted shoots<br />

(93.8 %) and highest root number (3.7 roots per shoot) were achieved <strong>in</strong> 1.0 mg l -1 IAA –<br />

conta<strong>in</strong><strong>in</strong>g medium after exposure to six immersions per day, ten m<strong>in</strong>utes each. The mean<br />

survival rate of plants rooted <strong>in</strong> TIS was 94 % under standard greenhouse conditions.<br />

Key words: adventitious shoots, immersion frequency, <strong>in</strong> <strong>vitro</strong> culture, multiplication,<br />

root<strong>in</strong>g, thidiazuron<br />

Abbreviations: BAP�6-benzylam<strong>in</strong>opur<strong>in</strong>e; IAA�<strong>in</strong>dole-3-acetic acid; NAA�1naphthaleneacetic<br />

acid; PLB�protocorm-like body; TDZ�N-phenyl-N’1,2,3-thiadiazol-5ylurea<br />

(thidiazuron); TIS�Temporary Immersion System<br />

1. Introduction<br />

Micropropagation of Phalaenopsis has <strong>in</strong>creased remarkably <strong>in</strong> Europe<br />

over the last few years. In Germany 9.2 million plants were multiplied <strong>in</strong><br />

2000, 15.1 million <strong>in</strong> 2001 and 22.8 million <strong>in</strong> 2002 (Preil, 2004). The<br />

turnover of Phalaenopsis, occupy<strong>in</strong>g the lead<strong>in</strong>g position <strong>in</strong> pot plants <strong>in</strong> the<br />

231<br />

A.K. Hvoslef-Eide and W. Preil (eds.), <strong>Liquid</strong> <strong>Culture</strong> <strong>Systems</strong> <strong>for</strong> <strong>in</strong> <strong>vitro</strong> <strong>Plant</strong> <strong>Propagation</strong>, 231–242.<br />

© 2005 Spr<strong>in</strong>ger. Pr<strong>in</strong>ted <strong>in</strong> the Netherlands.

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