Studies On Nutritional Growth Characteristic And Key Skills Of Flue-Cured Tobacco Seedlings In The Floating System

The studies on basical growth rules and nutritional physiological characteristics and skills of flue-cured tobacco seedlings in the floating system were done with NC89 and commercial medium and fertilizer offered by Yexian tobacco company in Henan Agricultural University during 2000-2002. The results were as follows.The first results were about basical growth rules of flue-cured tobacco seedlings in the floating system. Stem height and fresh weight one root and fresh weight one stem took on one continuously increasing trend during the whole tobacco seedlings' stages; stem circumference and dry weight one root and dry weight one stem took on one slowly increasing trend and one rapidly increasing trend in early stage and late stage of tobacco seedlings respectively; the change of spiral-root formation percentages was having one rapidly increasing trend during three and four leaves stage and kept a basically steady trend after that.The accumulation of dry matter in seedlings' root and stem and leaf and the whole plant were shaped on logistic curve and arrived at positive relevance level during the whole growth stage. The distribution of dry matter in each organ was leaf>root>stem in two to three leaves stage and the distribution of dry matter in each organ was leaf>stem>root in three to four leaves stage; the distribution ratio of leaf dry matter was higher in early stage and later took on one slow trend with a quickly decreasing trend in seven point five leaves stage; the distribution ratio of root dry matter was quickly increasing in three and four leaves stage and later having one steadily increasing trend; the distribution ratio of stem dry matter was steadily increasing as tobacco seedlings growth stages were pushing on and having a rapidly increasing range.The studies also showed, the chrolophyll content and SOD and NR activity of tobacco seedlings leaves and root vitality all presented a gradually increasing trend in whole growth stages; the change of INV activity of leaves kept a relative steady state basically in the whole tobacco seedlings growth stages.During the whole tobacco seedlings growth stages in floating system, the absorption amounts' tread of mineral elements in tobacco seedlings' leaves was N>Ca>K>P2O5, Mg>Fe>Mn> Zn>Cu. K, Ca, Mg contents of tobacco seedlings were richer than those of tobacco plants, especially two to three leaves stage. During flue-cured tobacco seedlings in the floating system, N contents of tobacco leaves took on a firstly increasing and seconddecreasing and then increasing change; P2O5 contents of tobacco leaves took on a increasing change; K contents of tobacco leaves took on a decreasing change; Ca, Mg contents of tobacco leaves took on a firstly decreasing and then increasing change; Fe, Zn, Cu contents of tobacco leaves presented a gradually decreasing trend and Mn contents of tobacco leaves presented a gradually increasing trend.The second results were about fertilizer effects on flue-cured tobacco seedlings in the floating system. The urea-N levels experiment showed, the parameter values of 15 percents urea-N had no striking difference than CK, This meant urea-N could provide some N fertilizer in the production of floating system to decrease fertilizer costs; the parameters values of 45percents urea-N and 75percents urea-N had more different distinction than CK, and the latter' parameter values were strikingly lower than CK. The phosphorus levels experiment showed, phosphorus-applied treats' tobacco seedlings had a better growth and the chrolophyll content and NR activity of tobacco seedlings leaves and root vitality all reached extremely striking level than no phosphorus-applied treats, and phosphorus-applied treats' tobacco seedlings' leaves had richer mineral elements; lOO-lSOmg.L"' phosphorus treats was the best among phosphorus-applied treatments. The potassium levels experiment showed different potassium levels had different influence on growth and development of Flue-cured tobacco seedlings in the floating system, 50-lOOmg.L"1 potassium level...