| This thesis is to ascertain the effects of group size and allocation.They affect field growth of Yunyan 116,carbon and nitrogen metabolism,and yield and quality of flue-cured tobacco leaves.So as to reasonably allocate the group structure of Yunyan116 in Weining Tobacco Area.Then these can provide technical support for its supporting cultivation techniques and variety promotion.First ensuring that a certain total effective leaf number was kept on a unit area of land after topping the flue-cured tobacco group,this experiment was conducted to control the group structure of flue-cured tobacco by changing the planting density.Secondly,set three levels for group size(16,000 pieces/667m~2,18,000 pieces/667m~2,20,000 pieces/667m~2).Then set three levels for planting density(900 plants/667m~2,1,000 plants/667m~2,1,100plants/667m~2),and combined into 9 for treatment.The field random block experiment was carried out in Weining Heishi Hi-tech Park.The experiment adopted consistent nitrogen application rate per mu of flue-cured tobacco.It also researched the effects of different group size and allocation on field growth of Yunyan 116,on content of main carbon and nitrogen metabolism products in tobacco leaves(starch,total sugar,reducing sugar,total nitrogen,nicotine,protein),on activity of carbon and nitrogen metabolism key enzymes(SPS,INV,SS,α-Amylase,NR,Ni R,GS,GOGAT),expression quantity of carbon and on nitrogen metabolism key enzyme genes(Nt SS,Ntα-Amylase,Nt NR,Nt GS),and finally economic traits and chemical quality of flue-cured tobacco leaves.The main conclusions were as below:1.Effects of group size and allocation on field growth of Yunyan 116Before topping and leaf retention of tobacco plants:from the stage of cluster planting to the stage of budding performed that,following the decrease of planting density,the relative content of chlorophyll in tobacco leaves was increased,the photosynthetic efficiency was raised,the dry matter accumulation quantity of tobacco plants was increased,and the agronomic traits were optimized;at each stage,the leaf area index of flue-cured tobacco group was the largest under low density treatment,and the group growth rate was the highest under high density treatment.After topping and leaf retention of tobacco plants:the stage of doming performed that,under high group leaf retention number(group size)treatment,the relative content of chlorophyll in tobacco leaves and the dry matter weight of single plant tobacco leaves were the highest,the maximum leaf length and the maximum leaf width of lower and middle leaves performed better,and the leaf length and width of upper leaves were relatively small.Overall,the field growth performances of Yunyan 116 performed best under the high group and low density combination.2.Effects of group size and allocation on field tobacco leave carbon metabolism of Yunyan 116Before topping and leaf retention of tobacco plants:the stage of budding performed that,following the increase of planting density,the content of tobacco leaf starch,total sugar and reducing sugar was increased gradually,the activity of tobacco leaf SPS and SS and the expression quantity of Nt SS and Ntα-Amylase were reduced gradually,the activity of tobacco leafα-Amylase and INV was the strongest under low density,and the carbon catabolism was vigorous,which were conducive to the growth and development of tobacco plants in the early stage of field.After topping and leaf retention of tobacco plants:the content of tobacco leaf starch and reducing sugar under high group leaf retention number treatment was the highest,the activity of SPS and INV was the strongest,the expression quantity of Nt SS was the highest,the activity ofα-Amylase and SS was the weakest,and the carbon accumulative metabolism was vigorous;the low-density and medium-density allocation for the high group leaf retention number was conducive to the accumulation of tobacco leaf starch,and the improvement for activity of carbon metabolism key enzymes in the later stage of field.Different group density combinations had significant effects on the content of carbon metabolism products in middle leaves of tobacco plants.3.Effects of group size and allocation on field tobacco leave nitrogen metabolism of Yunyan 116Before topping and leaf retention of tobacco plants:the stage of budding performed that,following the decrease of planting density,the content of tobacco leaf total nitrogen,nicotine and protein was increased gradually,the activity of Ni R was strengthened,the expression quantity of Nt NR and Nt GS was increased,the activity of NR was the highest under low density,and the tobacco leaf nitrogen metabolism was vigorous,which were conducive to the growth and development of tobacco plants in the early stage of field.After topping and leaf retention of tobacco plants:the stage of doming performed that,the content of tobacco leaf total nitrogen,nicotine and protein under low group leaf retention number treatment was the highest,the activity of NR,GS and GOGAT was the strongest,and the nitrogen metabolism was vigorous;the content of tobacco leaf total nitrogen,nicotine and protein under high group leaf retention number treatment was the lowest,and the activity of NR,GS and GOGAT was weak,which were conducive to the transformation of tobacco plants from nitrogen metabolism to carbon metabolism in the later stage of field.Different group density combinations had the significant effects on the content of nitrogen metabolism products in lower and upper leaves of tobacco plants,but there was no significant difference in the content of tobacco leaf nitrogen metabolism products among different density allocations under high group leaf retention number treatment.4.Effects of group size and allocation on economic traits and chemical quality of flue-cured tobacco leaves of Yunyan 116The yield and output value were the highest under high group leaf retention number treatment,among which the yield and output value of the high group and low density combination were the best,which were 130.65 kg/667m~2and 4,188.40 yuan/667m~2;the average price and super-class tobacco rate were the best under low group leaf retention number treatment;there was no significant difference in the middle and super-class tobacco rate among the group density combinations.The content of total sugar and reducing sugar in flue-cured tobacco leaves of each group density combination was relatively high,the content of total nitrogen,nicotine and chlorine was appropriate,the content of starch in middle and upper leaves was appropriate,the potassium chloride and nitrogen alkali were coordinated,the sugar alkali in lower and middle leaves was coordinated,and the sugar alkali ratio in upper leaves under high group leaf retention number treatment was within the appropriate range.The CHS evaluation of lower and middle leaves under high group leaf retention number treatment was relatively low,but all chemical components were within the appropriate range of high-quality tobacco,and the CHS evaluation of upper leaves was the highest,with the best usability.To sum up,this research treatment,taking the group size as 20,000 pieces/667m~2,and density and leaf retention number allocation as 900 plants/667m~2—single plant leaf retention of 22 pieces,was conducive to the field growth and carbon and nitrogen metabolism of Yunyan 116 in Weining Tobacco Area,and was helpful for promoting the economic traits and chemical quality of flue-cured tobacco leaves of Yunyan 116. |
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