Effect Of Nitrogen Rate And Planting Density On Guizhou Flue-cured Tobacco Growth And Yield Quality

The experiment which carried in field plot and used main tobacco varieties K326 and Nanjiang 3 in GuiZhou as the material,researched middle flavor flue-cured tobacco growth and development,and established the model of middle flavor characteristic high-quality tobacco growth and development.The results were as follows:The trend that signal plant true leaves occurred,along with growth and development,showed "S" curve.The period of tobacco Nanjiang 3 leaves occurred was longer than K326 about 14 days and the peak period of tobacco Nanjiang 3 leaves occurred was longer than K326 about 5 days,but rate of leaves occur was lower than the K326 about 0.2?0.3 pieces per day.The final true leaves in K326 conventional cultivation,cultivation of tobacco control nitrogen densification,Nanjiang 3 conventional cultivation,cultivation of tobacco control nitrogen densification,were 40,39,42,42 pieces per plant respectively,and number of leaves harvest per plant were 21,21,25,25 pieces respectively.The time of tobacco K326 and Nanjiang 3 middle leaves from occurring to fixed length was the longest and upper leaves was the shortest.The leaves fixed length time in K326 and Nanjiang 3 conventional cultivation is longer than cultivation of tobacco control nitrogen densification about 2 days.Nanjiang 3 middle leaves fixed length time longer than K326 about 3 days,and upper leaves fixed length time shorter than K326 about 3 days.The time from leaves fixed length to harvest was extended along with the rising of leaf position.Lower leaves fixed length to harvest time was the same in every treatment,and all were 17 days.The time of K326 and Nanjiang 3 middle and upper leaves fixed length to harvest in conventional cultivation was longer than cultivation of tobacco control nitrogen densification about 2?3 days and 3?5 days,respectively.The time of Nanjiang 3 middle and upper leaves fixed length to harvest was longer than K326 2?3 days and 5?7 days respectively.As to the time of dry matter accumulation,in two kinds of cultivation modes,lower leaves was not obvious difference,but middle and upper leaves in conventional cultivation were longer than cultivation of tobacco control nitrogen densification about 10 days.There were no significant difference among varieties.The rapid growth period of root system was 45?90 days in K326 conventional cultivation,Nanjiang 3 conventional cultivation and cultivation of tobacco control nitrogen densification,and it was 45?75 days in K326 cultivation of tobacco control nitrogen densification.The root system biological trait of conventional cultivation was better than cultivation of tobacco control nitrogen densification,indicating root system growth tend to fertilizer.Under the same cultivation mode,in transplanting 75 days ago,the root trait of Nanjiang 3 was worse than K326,but after transplanting 75 days,it was better than K326.Indicating Nanjiang 3 explosive force in early stage was inadequate,and was strong in late stage.Tobacco plant dry weight showed significant logistic growth curve along with the growth and development process.In the field groAwth and development process,the tobacco plants were no significant difference in dry weight for 4 treatments in transplanting 30 days ago.But after transplanting 30 days,cultivation of tobacco control nitrogen densification was less than conventional cultivation.After transplanting 45?75 days,K326 tobacco plant dry weight was more than Nanjiang 3,but later was less than Nanjiang 3.The rapid accumulation period of tobacco plant dry weight in K326 conventional cultivation and cultivation of tobacco control nitrogen densification was after transplanting 45?90 days and 45?75 days respectively.Meanwhile,it was after transplanting 45?105 days in Nanjiang 3 two cultivation mode.Along with tobacco plant growth and development process,dry matter accumulation intensity showed a parabolic trend.During cured tobacco field growth,field leaf area index of Nanjiang 3 presented a parabolic trend.The maximum value appeared after transplanting 60-90 days.Then,K326 showed a single peak curve change,the maximum value appeared after transplanting 60 days.The net assimilation rate presented a single peak curve change,and the maximum value appeared after transplanting 45-60 days.But after the K326 peak,it sharply declined.In transplanting 75 days ago,population physiological indices of K326 was better than Nanjiang 3,and after that was less than Nanjiang 3.Cured tobacco leaves major economic of cultivation of tobacco control nitrogen densification was not significant difference with conventional cultivation.But the balance of chemical components of cultivation of tobacco control nitrogen densification was better conventional cultivation.