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Abstract: Volatile constituents of embryogenic and nonembryogenic sweet orange (Citrus sinensis (L.) Osbeck) callus cultures were analyzed by gas chromatography-mass spectrometry to determine if sweet orange flavor essences were produced. Fifteen compounds were identified from the embryogenic callus methylene chloride extracts, with 10 previously reported as volatile constituents of orange juice or peel essential oil, 3 are known fermentation products, 2 have no reported aroma, and 2 were unknown. No volatile compounds were detected from nonembryogenic callus methylene chloride extracts.

Cotyledonary explants of 4-day-oldCucumis melo cv. ‘Hale's Best Jumbo’ in vitro seedlings showed maximum initiation of shoot buds when cultured onto a revised Murashige & Skoog medium supplemented with 5 µM indole-3-acetic acid and 5 µM benzylaminopurine and cultured at 25–29°C under low light intensity (5–30 µmol m-2 s-1). Subculture of the shoot buds onto the same medium without auxin and supplemented with 3 µM benzylaminopurine caused the development of shoots from 30% of the buds. The presence of abscisic acid significantly increased the number of explants producing shoot buds. Bud initiation was affected by genotype, seedling age, light intensity, and temperature. Addition of gibberellic acid, thidiazuron or silver nitrate to regeneration medium did not improve either bud initiation or shoot regeneration.