Author : Grisana Linwattana

Summary : Vernalization of non-heading Chinese cabbage for eight days at 5 degree Centigrade induced flowering at least two weeks earlier than normal. Devernalization occured in vernalized plants when they were exposed to temperature of 30 degree centigrade or higher even for only one day. Gibberellic acid at 50-100 ppm applied two weeks after transplanting for four weeks was not able to subtitute for vernalization. However, the number of leaves, leaf size, and plant weight decreased. Similarly, vernalization suppressed leaf length and width and plant weight by 26.3 percent and 46.8 percent respectively, before transition to the reproductive stage. The combination of vernalization and gibberellic acid had a synergistic effect on seed yield. Paclobutrazol, a gibberellin biosynthesis inhibitor, delayed flowering when applied at 100 ppm before vernalization. When 100 ppm gibberellic acid was sprayed on the paclobutrazol-treated plants, flowering time did differ from that of the vernalized control. This suggested gibberellin involvement in vernalization. However, the time of harvesting and seed vigor and germination were not affected by any of the treatments applied.