| Summary: | 碩士 === 國立嘉義大學 === 農學研究所 === 99 === A new favorite product of using the young seedlings to produce mini-plant types of 18-cm green braid seedlings of Malabar Chestnut in Japanese, the U.S. and European markets. This study was to investigate the shade, sowing medium, time of water loss and retardants on the growth and quality of green braid seedlings in Malabar Chestnut. The experiment results showed that 60% and 80% shading treatments were compared to the control group, not only had a significant efficiency to elongate above 4~5 cm of the hypocotyls length and achieved the 12-cm length hypocotyls of commercial standard, but also the diameter of hypocotyls followed with the increase of shading intensity to reduce to 5.2~5.7 mm of tiny level. But the internodes length above cotyledons also appeared the excessive elongation of negative phenomenon. In addition, seeds sown in peat moss, coir dust, and medium of sand mix rice husk with 80% shade treatment, the germination speed were rapidly reached up to 80% of germination rate after 6~day sowing. After 7~13 days sowing, up to 80% of seedlings reached the take seedlings standard in 12-cm length hypocotyls. Planting density test showed that medium of rice husk mixed sand in 3 cm x 3 cm or 6 cm x 6 cm of high-density planting, the germination rate was fast and uniform, and could replace the other imported media for the greenhouse production applications. Besides, when the hypocotyls length of seedlings reached the standard of 12 cm, seedlings were selected and put in the indoor environment (30 ℃, relative humidity 65%) for experiment of water loss, its stress value decreased rapidly to 20~30 kpa after 36-hour water loss. On the other hand, braiding the seedlings after water loss treatment and then planting in the 9-cm diameter pot after 30 days to investigate the crack index of hypocotyls. Results demonstrated the water loss for 24~36 hours of the braiding seedlings had the smallest crack index, induced the braiding seedling hypocotyls showed the best quality of outward appearance. Moreover, among the growth retardants treatment showed that the total internodes length above cotyledon and plant height followed with the increase of retardant concentration and spray frequency had a significant reduction effect, among which by Paclobutrol treatments had the more efficiency on reducing the internodes length, but could not affect the formation of nodes number. Therefore, the suitable for plant height and appearance quality of green braid seedlings were recommend an appropriate concentration and spraying times by 15 mg•L-1 paclobutrol spraying two times. However, the best effect by Chlormequat Chloride (CCC) treatment was recommended by 346 mg•L-1 spraying two times. In addition, the spraying time of two retardants had the same dwarfing effect whether before selecting seedlings or after braiding and then transplanting in pot. Therefore, the practical operation suggested for the first spray time at the hypocotyls length of seedlings to standard length, and then spraying the second time at the completion braid seedlings transplanted in pot. However, according to our experiment results also demonstrated the effectiveness of over-dwarf and production of abnormal leaves when the retardants concentration was higher than the recommended concentration or spraying frequency was more than three times. It will greatly affect the ornamental quality of green braid seedling in Malabar chestnut.
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