Effects Of Planting Density On Growth And Its Mechanism Of Flue-cured Tobacco NC55

Adjusting planting density has important practical significance for ideal plant type building and the promotion of yield and quality in flue-cured tobacco.This study used field trials with cultivation variety NC55 as material in Shandong tobacco growing areas,sets up four planting density under 13880plants/hm~2-55500 plants/hm~2.This study mainly aiming at different planting density to analysis it's effect on plant botany character,the change of matter accumulation,variation of photosynthetic pigment and photosynthetic performance and chemical components.The main results were as follows:1.Leaf length,leaf width,leaf area were increased with the reduce of planting density,the ratio of leaf length and leaf width were decreased with the reduce of planting density.Increasing planting density resulted to the decrease of leaf area of single plant.Even so,the leaf area index of high planting density treatment is the highest performance.The leaf area conforming to a Logistic model.According to the Logistic model,the leaf area showed lower leaves area>middle leaves area>upper leaves area in treatment M1,M2 and M3,middle leaves area>lower leaves area>upper leaves area in treatment M4when leaves reach the biggest.With the increase of planting density,stalk width were reduced,plant height and pitch was increased.2.Reduce the planting density achieved maximum root,stem,leaf dry weight and individual biomass,increase planting density achieved the smallest the ratio of stem and leaf,the largest biomass per area.In treatment M3,the root-shoot ratio was largest,root development was most flourishing relatively.Lower planting density promoted leaf dry matter accumulation,the dry weight of leaf vein,leaf mesophyll,total leaf and vein-mesophyll ratio were increased with the reduce of planting density and leaf position rose.Leaf water content is not significantly affected by planting density,with the growth period and leaves position rise decreased.At mature stage,root,stem and leaf nitrogen content in treatment M4 was highest,potassium content in medium planting density were lower.Colony and single plant nitrogen,potassium accumulate stage concentrate on resettling stage-vigorous growth and squaring stage-mature stage in treatment M2,M3 and M4,nitrogen and potassium accumulate amounts and rate were higher in treatment M1.3.The total content of chlorophyll and carotenoid content had a tend to be reduced with the planting density rise,the effect of planting density on the ratio of chlorophyll a and chlorophyll b was not obvious.Planting density had strong influence on Pn and Tr,according to different period,effects on Gs in the mature stage,effects on Ci on resettling stage and squaring stage was not remarkable.Pn,Gs,Tr rose with the planting density increasing,and Ci on the contrary.Plants had strongest photosynthetic capacity in treatment M4.4.With the planting density decreasing,the content of reducing sugars and total sugar of flue-cured tobacco decreased,the content of N and plant alkaloid increased,in treatment M4 had the optimal reducing sugar,total sugar,total alkaloids and nitrogen content,but the chemical composition coordination was the worst.With the planting density increasing,the sugar content one the high side and N content was lowest,but the value of sugar alkali,SUR/NIT increased and in treatment M1 reached the ideal harmonization.Tobacco response to the change of planting density by nutrient and light competition,then affects the root,stem and leaf growth and photosynthetic performance,thus significantly affect the distribution and accumulation of dry matter and tobacco chemical composition.Considering yield and quality overall,18500 plants/hm~2-27750 plants/hm~2 on Weifang Shandong is the best planting density range with high quality and efficient,can solve the problem of tobacco economic yield is not enough supply.