| Lushi County of Sanmenxia is the largest tobacco planting area county in Henan Province.In recent years,the yield and benefit of tobacco planting were decreased gradually,owing to monocultured flue-cured tobacco variety Yunyan 87 and Yunyan 99 that leads to the aggravation of field diseases year by year.The new variety LY1306 with strong disease resistance,high quality and yield were selected through field experiments for many years in Lushi.Variety LY1306 has the potential to replace the varieties Yunyan 87 and Yunyan 99.In this study,the L9(34)experimental design were used to optimize cultivation techniques,according to the characteristics of LY1306 variety and climatic conditions in Lushi tobacco area.The effects of planting density(row and plant spacing 1.30×0.50 m,1.30×0.60 m,1.30×0.70m),nitrogen application rate(5.5kg/667m2,6.5kg/667m2,7.5kg/667m2)and leaves per plant(20 leaves,22 leaves,24 leaves)on the agronomic characters,growth and development,economic characters,upper leaf development and tobacco quality were studied.As well as the effects of upper leaf harvesting maturity on flue-cured leaves quality of LY1306 were also studied.The purpose was to provide a basis for the promotion and planting in Lushi and the improvement of flue-cured leaves quality of LY1306 in Lushi.The main results are as follows:Planting density and nitrogen application rate were the key factors affecting the field growth conditions of LY1306.With the decrease of density and the increase of nitrogen application rate in tobacco fast growing period,the leaf area index,dry matter weight,cauline leaf angle,and leaf width increased,the development of tobacco plant were accelerated and the filed growth period was shortened.With the increase of nitrogen application rate at round top stage,the cauline leaf angle,dry matter weight,chlorophyll content in middle and upper leaves,total sugar and reducing sugar content in leaves increased.Under medium and high-density conditions,the starch content decreased with the increase of nitrogen application rate,the expression levels of Nt GBSSI and Nt SBE genes were relatively high,and the carbon metabolism was vigorous.The relative expression levels of Nt GS1-3,Nt GS2,and Nt NR genes were higher under medium density density and high nitrogen application rate.With high nitrogen application rate and the nitrogen metabolism tobacco plants were more vigorous under high nitrogen application rate and the high number of leaves.The leaf width was mainly affected by planting density and leaves per plant.The accumulation of the biomass was beneficial from medium nitrogen application rate,and the area of the upper six tobacco leaves was mainly affected by leaves per plant and density.Lower planting density and higher nitrogen application rate were beneficial to the maturity of the upper six leaves of LY1306.Nitrogen application rate and leaves per plant were the main factors affecting the yield and output value of LY1306,nitrogen application rate and density were the main factors affecting average price,and density was the main factor affecting the percentage of middle and superior leaves rate.The yield and output value increased with the increase of nitrogen application rate under medium and low density conditions.LY1306 in Lushi tobacco area could obtain high economic benefit when nitrogen application rate is 7.5kg/667m2(average nitrogen application rate in local hilly land),plant spacing is 1.30×0.60 m or 1.30×0.70m(plant spacing is greater than average local production level),and leaves per plant is 22 or 20.Density and nitrogen application rate were the main factors affecting total nitrogen content,starch content,total sugar content,reducing sugar content and nicotine content in LY1306,and leaves per plant was the main factor affecting potassium content in middle leaves.The contents of reducing sugar and nicotine increased with decreasing density of upper leaves,while the contents of starch and total N increased with increasing density of middle leaves.The sensory quality of flue-cured leaves was mainly affected by nitrogen application rate and leaves per plant.Plant spacing 1.30×0.60 m,nitrogen application rate 7.5kg/667m2,leaves per plant 22,the middle and upper leaves has the highest sensory scores,good aroma quality,less miscellaneous gas,and abundant taste.The effects of upper leaf harvesting maturity on flue-cured leaves quality of LY1306 were studied.It was found that the length of upper 4-6 leaves increased with the decrease of maturity,and the potassium content of the upper 6 leaves increased with the decrease of maturity.The contents of total sugar and reducing sugar in fully mature leaves were higher,and the contents of total nitrogen and nicotine in 8-9 mature degree leaves were the highest.LY1306 leaves with high maturity have less miscellaneous gas,higher strength and fineness than those with low maturity.The total score of sensory quality increases with maturity,and the upper 4-6 leaves have better sensory quality.LY1306 leaves with full maturity had less miscellaneous gas,strong strength and flue gas concentration,and the best sensory quality.In conclusion,compared with cultivated varieties Yunyan87 and Yunyan99,LY1306 planted under low planting density,high nitrogen application rate and relatively more leaves per plant in Lushi could obtain reasonable plant type and coordinated C and N metabolism,which was more conducive to the maturation and yellowing of the upper six leaves,better yield and benefit,and better leaves quality.Increasing the harvesting maturity of six leaves on LY1306 was beneficial to improve the chemical composition coordination and sensory quality of flue-cured leaves.In the hilly land of Lushi county,the new variety LY1306 was cultivated and managed with key cultivation practices of plant spacing 1.30×0.60 m,nitrogen application rate 7.5kg/667m2,22 leaves per plant left and higher upper leaf harvesting maturity,which could obtain better yield benefit and better flue-cured leaves quality. |
PDF Full Text Request