The method involved soaking seeds in 5% sodium hypochlorite for 10 min, washing with tap water, and placing in petridish having two layers of filter paper pad for germination in incubator under the constant temperature of 28 C. When the radicle was 5 mm long, the seeds were sown individually into plastic pots filled with steam-sterilized propagation substrates. Propagation substrate was composed of peat, vermiculite, and soil from vegetable fields (2:1:1, volume basis) and was steam sterilized at 134 C for 30 min. Seedlings were placed in a growth chamber held at 25/20 C day/night with a 16-h photoperiod. Illumination was provided by high-pressure sodium lamps at 50 Wm–2.