The Effects Of Different Chemical Control Agents On The Strong Seedling Cultivation, Yield And Quality Of Flue-cured Tobacco

Taking'Xiangyan 3'as experimental material, tobacco seedlings were treated with different concentration of PP333, DPC and CCC by foliage spraying when the plant in the three to four leaves stage, the agronomic traits and physiological characteristics during seedling stage, the agronomic indexes during field period, the economic benefits and chemical components of baked tobacco leaves were tested. The main results were as follows:The plant height and the maximal leaf area decreased obviously while the stem diameter, root volume, ratios of root-shoot and dry-fresh increased with the use of chemical control agents, and the seedling dry weight raised; Among the three different plant growth retardants, the effects of PP333 were better than the others and strengthened as the concentration increased, A2 and A3 treatment were the optimal concentration for the agronomic indexes of tobacco seedlings. The effects of DPC and CCC weakened with prolonging of treating time, B3 and C3 treatment were the best.The chemical control agents had significantly influence on the physiological characteristics of tobacco seedlings. Comparing with the CK, the root total absorbing area and root activity elevated obviously, the content of chlorophyll and soluble sugar enhanced, the activity of SOD and POD improved, the level of MDA reduced. And the chlorophyll content appeared the trend of up-down-up" while the PP333 treatment showed an upward tendency. The impacts of DPC and CCC lasted for 1-3 weeks, PP333 had remarkable influence during the seedling stage, the A2?B2 and C2 treatment were better than others among chemical control agents.After tobacco transplanting, there was no significant difference between DPC?CCC and CK; As for PP333 treatments, the plant height reduced and the stem diameter thickened compared to the CK, but the inhibition effect gradually removed with the passage of time, tobacco restore growth and development, the variation was narrowed, and the difference among different treatments was not obvious.The yield and production value, average price and mid-high grade tobacco proportion increased with the use of PP333 and DPC, and PP333 had significantly impacts on the output, but no effects on other indexes; after spraying CCC the average price and percentages of high grade tobacco promoted while the yield and output value reduced, but it showed no obvious difference; the A2 and A3 treatment, B2 and B3 treatment, C3 treatment showed the best in the economic benefits.Spraying chemical control agents could promote the total sugar, reducing sugar, K and starch content while decrease the content of Cl, nicotine and total nitrogen of all leaves of tobacco, coordinate ratios of K/Cl and total nitrogen/nicotine of all leaves of tobacco and total sugar/nicotine of upper leaves of tobacco. However, there was no improved influence on the excessively high ratio of total sugar/nicotine of lower and middle leaves of tobacco.Comprehensive comparison, the effects of PP333 were better than the others; the 100mg/L treatment of PP333 had the optimal effects on strong seedling cultivation, yield and quality, when tobacco seedlings in the three to four leaves stage.