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Joint International Conference on Long-term Experiments ...

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The results showed a highly significant effect of the stage of explant. All the other<br />

acti<strong>on</strong>s are insignificant (table 6).<br />

Table 6 The effect of developmental stage of explant up<strong>on</strong> the rate of embryogenic<br />

inducti<strong>on</strong> in Q. frainetto (test Duncan)<br />

Stage of explants (zygotic Average <strong>on</strong> stages Significance of the<br />

embryos)<br />

differences*<br />

S1 0.746 A<br />

S2 0.548 B<br />

S3 0.488 BC<br />

S4 0.424 C<br />

*Differences am<strong>on</strong>g any variants followed by <strong>on</strong>e comm<strong>on</strong> letter are not significant.<br />

DS 5% for stage: 0,110-0,118.<br />

The high embryo inducti<strong>on</strong> rate in the stage 1 proved to be highly significant, as well as<br />

the very low embryo inducti<strong>on</strong> efficiency obtained in the stage 4.<br />

2.2 Bifactorial experiments in Quercus petraea: the effect of stage of explant and<br />

culture medium up<strong>on</strong> the embryo inducti<strong>on</strong> efficiency<br />

(4 stages x 4 culture media)<br />

All differences between the results obtained <strong>on</strong> different culture media and also the<br />

interacti<strong>on</strong>s stage x medium were insignificant, but the differences am<strong>on</strong>g stages were<br />

found to be highly significant (Table 7)<br />

Table 7 The effect of developmental stage of explant up<strong>on</strong> the rate of embryogenic<br />

inducti<strong>on</strong> in Q. petraea (test Duncan)<br />

Stage of explants (zygotic Average <strong>on</strong> stages Significance of the<br />

embryos)<br />

differences*<br />

S1 0.814 M<br />

S2 0.590 N<br />

S3 0.422 P<br />

S4 0.311 Q<br />

*Differences am<strong>on</strong>g any variants followed by <strong>on</strong>e comm<strong>on</strong> letter are not significant.<br />

DS 5% for stage: 0,086-0,093.<br />

CONCLUSION<br />

1. All oak species tested Quercus robur (three provenances), Q. petraea (<strong>on</strong>e<br />

provenance) and Q. frainetto (two provenances) and all provenances tested inside<br />

each species showed embryogenic ability: the possibility of somatic embryo<br />

inducti<strong>on</strong> out of very juvenile explants (cotyled<strong>on</strong>s of immature zygotic embryos).<br />

2. The efficiency of somatic embryo inducti<strong>on</strong> varied between the variants of the<br />

experiment from 50 % (Q. robur, provenance Tg. Mures, stage 1) to 1,7 % (Q.<br />

frainetto, stage 4), excluding the variants giving negative results, especially those<br />

with explants in the stage 4.<br />

3. The most important factor affecting the efficiency of somatic embryo inducti<strong>on</strong><br />

450

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