Effects of Distiller's Grain Substrate with Acid Regulation on the Growth of Tobacco Seedlings in Floating Breeding System

In order to reduce the use of peat resources and realize the sustainable development of tobacco, the pH of distiller s grain substrate was adjusted with humic acid, and the effects of various distiller s grain substrates on the growth of tobacco seedlings were studied to find out the method of cultivating high-quality tobacco seedlings by using distiller s grain substrate. The results showed that when 60% of humic acid was added to the distiller s grain substrate made from coarse distiller s grains, fine distiller s grains, perlite and vermiculite, both the pH and electrical conductivity decreased significantly and were similar to that of the conventional substrate. Moreover, the emergence rate of tobacco seedlings, the rate of strong tobacco seedlings, leaf number, stem height, root growth and quality of tobacco seedlings were good.

Study on Selection and Application of New Matrixes for Floating Tobacco Seedlings

[Objective] This study aimed to verify the effects of new matrixes on tobacco seedlings on floating platform or field, and their effects on tobacco leaf yield and quality. [Method] The ratio of peat： carbonized rice hull： perlite： sand in the four new matrixes was 10∶40∶30∶20, 20∶40∶10∶30, 20∶40∶30∶10 and 20∶50∶10∶20, marked as T1, T2, T3 and T4, respectively. The ratio in control matrix was 35∶40∶25∶0. [Result]In formulas T1, T2, T3 and T4, the peat consumption was reduced by 70.1%,41.5%, 41.5%, and 41.5% respectively, which saved 12.5%, 23.1%, 8.2% and 12.8%of the cost. The new matrixes can effectively increase the seedling emergence rate of tobacco. The quality and duration of seedlings in float system with new matrixes showed no difference from those of control matrix. The values of output using the new matrixes were 323.10, 92.25, 39.30 and 2 250.60 Yuan/hm2higher than that of the control. Besides, the proportion of the first- and second-rate tobacco leaves was also improved. [Conclusion] These four new matrixes can be widely applied to raise seedling in a float system, and T4 is the best choice.

Identification of a Tobacco Disease on Flat Tray System

[ Objective] The pathogen of a new disease found in floating seedlings of tobacco was isolated and identified to provide the basis for the control of the disease. [ Method] The pathogenicity of the isolated strain was determined according to Koch＇s rules, and the pathogen was identified through Biolog system, 16S rDNA sequence analysis and physiological and biochemical methods. [ Result] Through Koch＇s test, the isolated 3 -3 strain was verified to be the pathogen causing floating seedling disease, which was consistent with the characteristics of Pectobacterium carotovo- rum subsp. Carotovorum through Biolog determination and the other physiological and biochemical methods. 16S rDNA sequence analysis showed that 3 -3 strain had the highest similarity with P. carotovorum subsp. Carotovorum strains Kun28213 （accession number GU936996）, reaching 99. 9%. [Conclusion] Base on the identification results of several methods, the pathogen causing floating seedling disease was P. carotovorum subsp. Carotovorum, and the disease was first reported in China. According to the English name of the disease, the disease was called as tobacco blackleg disease.