Study On The Technique Of Flue-cured Tobacco Seedling Production With Direct-seeded Floating System

In the world, technique of direct-seeded floating system for tobacco production was a new technique applied in the early 1990' s. Our province began this research for spreading in the northwest of Hunan province in the latter 1990' s. Based on the social economical condition and natural ecology environment such as the soil condition and climate condition, we began to establish the technique of direct-seeded floating system adapted to the northwest of Hunan, which in accord with our factory' s aim and standard. This study is mainly about medium, fertilization, tray, seedling clipping, hardening, growth regulator and seedingtime. As the results show that in the experiment of medium, two sorts of medium have no significant differences. Two kinds of medium have steadily chemistry characteristics and good properties in maintaining water. Algae would not grow on the two sorts of medium. 200-cell tray was the best choice that could cultivate healthy and regular seedlings. As to nutrient solution of the experiment, it was suggested that NIP! K=l : 0.5 : 1 and "150 mgN ?L'1" should be the best choice and the agronomic characteristics should superior to the other treatments. When "lOOmgN ?L"1" with the same N-P-K ratio 20 days after seedlings appearance was applied the tobacco grew better. Application of microelements could significantly improve the seedling quality. Moreover, the treatment 1 could reach the significant level. It was shown that when harden seedlings 4?6 days, tobacco stems could grow toughly. It was also suggested that the method of float seedlings production should have significant differences contrasted to nutritive soil seedlings production in all agronomic characteristics. When advanced the seedtime properly based on the traditional seedingtime, the tobacco seedling would benefit from it. If putting off the seedingtime, the rice paddy would be affected seriously. In the experiment of growth regulator, PPP333 and S3307 could control the growth process of the seedling effectively and the seedling could recover in extending-root stagecontrasted to the treatments of Fix and CCC, which need more time for recovering. When the Seedling treated by PPP333 and S3307, the output and production value increased markedly. On the contrary when treated by Fix and CCC, the output and production value was inferior to CK. As to the experiment of clipping, three-time clipping frequency will be good to tobacco seedlings.