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Keywords
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pummelo, nodal explant, organogenesis, growth regulator, culture medium.
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Abstract
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Micropropagation techniques play an important role to conserve elite or rare plants threatened with extinction. A study was carried out to find a regeneration protocol for an elite seedless clone of pummelo (Citrus grandis [L.] Osbeck.), BLRV, using mature nodal explants. 6-Benzyl adenine (BA) with and without α-naphthalene acetic acid (NAA) was used to induce multiple shoots. 0.75 mg l-1 was found as the best concentration of BA in induction of multiple shoots whereas use of 0.1 mg l-1 NAA in BA-containing media made no significant changes in the measured characteristics. Among half and full strength Murashige and Skoog (MS) media, Murashige and Tucker (MT) medium, and Woody Plant Medium (WPM), full strength MS medium yielded the best results in shoot induction from in vitro nodal explants inducing about 94% of explants to regenerate averagely 3.5 shoots and 3 usable shoots with mean length of 1.8 cm. Cent per cent rooting in microshoots was achieved by individual application of indole-3-butyric acid (IBA) at 4 mg l-1 in half strength MS medium within two weeks after culture initiation. This treatment resulted in the highest root length (average 7.25 cm), too. NAA did not yield satisfactory results since it caused formation of short and deformed roots which was probably the main cause for stunted shoot growth. In this study, a two-stage regeneration protocol was optimized for in vitro production of pummelo plantlets.
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