In Korea an early transplanting system under vinyl mulching (on April 5th), which was devised to protect seedlings from frost after transplanting and to hasten harvest before the rainy season, was compared to conventional transplanting (on May 5th). Early transplanting under vinyl mulching has shown increased plant height, length and width of largest leaf with a 25 per cent rise in yield ; however, days to flower did not change. The contents of reducing sugar, petroleum ether extract and essential oils increased with early transplanting but total nitrogen, protein nitrogen and nicotine contents did not vary. Environmental factors affecting the levels of aroma volatiles are also discussed.