| The southwest parts of Hubei Province in China are one of the main areas of planting flue-cured tobacco. The Enshi region is the main tobacco producing areas of Hubei Province for a good ecological and soil conditions richly endowed with the natural conditions for the production of high quality tobacco. In order to further study the effects of physiological and cultivation factors for the higher yield and better quality tobacco production in Enshi mountainous regions, using the flue-cured tobacco variety Yunyan 87 as materials, the four culture factors(transplanting days, plantation density and nitrogen fertilizer amount, the number of leaves per individual plant)culture modes were performed with uniform design test with five different levels in five culture modes in the tobacco research base of Lichuan city, Enshi prefecture, the roots, stems and leaf tissues, at 30 days 45 days, 60 days, 75 days and 90 days after transplanting, were determined to the dynamic variation of the contents in the inorganic ions(N, P, K, Cl), carbohydrates(total sugars, starch, cellulose, crystalline cellulose), nitrogenous compounds(NO3-, NO2-,free amino acids, total proteins, the of nicotine);Analysis of the correlation was made between the physiological indexes of different days after transplantation and also the four cultivation factors and economic characters or sensory parameter scores flue-cured tobacco leaves, to find out the influence factors and key cultivation key chemical indexes for the flue-cured tobacco economic traits and sensory evaluation scores. The main results are as follows:1. In the all five cultivation modes, roots, stems and leaf tissues exhibited the great changes in the content ranges and correlation in the inorganic ions, carbohydrate and nitrogen compounds content, indicating the complex interactions among them.2. Stepwise regression analysis showed that, during the five different days after transplanting, starch, cellulose crystalline cellulose, free amino acid and chloride ion were the main physiological indexes of flue cured tobacco sensory evaluation score. Moreover, 45 d, 75 d and 90 d were the paramount periods for the above indicators.3. Correlation analysis of economic traits demonstrated that, there were nitrogen fertilizer amount was positively correlated with yield, output value and average price, respectively, but negatively correlated with superior tobacco ratio and medium-superior tobacco leaves; planting density was negatively correlated with yield, output value and average price, but positively correlated with the ratio of first-class tobacco and medium-superior tobacco; the number of remaining leaves was positively correlated with all of economic characters, and also significantly positively correlated with output value and average price.4. Stepwise regression analysis showed that, transplanting period, planting density and the number of leaves was the key factor to affect the yield of flue-cured tobacco, transplanting period and the number of remaining leaves is the key factor for medium superior tobacco rate. As the transplanting date is May 28 th, the planting density was 700/667m2, the number of leaves is 23, the highest yield and superior tobacco ratio will attain.5. The cultivation mode N4 have the highgest absorption and utilization efficiency of nitrogen fertilizer, the cultivation mode N2 have the highgest absorption and utilization efficiency of phosphate fertilizer and potassium.6. The significant test showed that, there are significant differences in the economic character and sensory parameter score performances in flue cured tobacco and tobacco sensory indexes of the five different cultivation modes. In addition to the similarity to Mode N1 in yield, flue-cured tobacco of Mode 4 showed the highest rate in the output value, tobacco and sensory indexes. Therefore, N4 is the optimal cultivation mode in this experiment. |
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