| Changes of bulb sprouting rate, starch grain in the scales of outer and inner layer, structure and ultrastructure of shoot-tip in Lilium brownii var. viridulum of tube culture during storing at 5℃ and 25 ℃ were investigated by using transmission electron microscope and paraffin slices. The relationship between these changes and dormancy release was discussed. The results were as follows:The effects of storage temperature and time on bulb sprouting rate were obvious. It was more favorable for releasing dormancy to be stored at 5℃ than at 25 ℃. The sprouting rate of bulbs was 95% after 60 days at 5℃ and was 98% after 90 days. When they were stored at 25 ℃, most of them can not release dormancy after 60 days, their sprouting rate was only 17% after 90 days. The effects of storage temperature and time on starch grains in the scale of outer and inner layer were also obvious. During storing at 5℃, starch grains became smaller gradually, their outline became more indistinct from clear, but during storing at 25 ℃, their changes had not obvious. Furthermore structure and ultra-structure of shoot-tip of bulb had different changes at different storage temperature. When they were stored at 5℃ for 30 days, their shoot-tip began cell division and chromosomes can be seen distinctly. At the 40th day the hearty cell division of shoot-tip promoted to form new phyllome. During storing at 5℃, organelles in shoot-tip cell had obvious changes, such as the nuclear became bigger gradually; mitochondria increased largely and distributed mostly near nuclear and cell membrane, cristaes in them also increased; the central vacuoles divided into the small vacuoles and phagosomes in them disappeared; amyloplast became proplastid slowly, lipid body increased abruptly at the 30th day; endoplasmic reticulum increased gradually. On the contrary, during storing at 25℃, the shoot-tip cells were at dormancy state after 90 days, organelles had not obvious changes, only vacuoles and lipid body had a little change. |
