Effect Of Reducing Nitrogen On The Physiological Metabolism And Quality By Liquid Fungal Fertilizer Of Slope Flue-cured Tobacco

Based on the principle of dynamic nutrition supply balance of flue-cured tobacco,a fine and reasonable cultivation model of reducing nitrogen and coordinating carbon and nitrogen metabolism was studied by means of integrated technology of water and fertilizer,which could provide a reasonable model for increasing yield and quality of flue-cured tobacco in sloping field of north Guangdong Province.Nicotiana Tabacum L.Variety‘Yueyan 97’was used as experimental material,and five treatments were set up,BC was Blank Control,CK was conventional management of Water and fertilizer,K1 was application of liquid bacterial fertilizer without reducing nitrogen,K2 was application of liquid bacterial fertilizer with reducing nitrogen by 10%,K3 was application of liquid bacterial fertilizer with reducing nitrogen by 20%,in 2018 and 2019 respectively in Xingzi town,Lianzhou,Guangdong Province,and Shixing County,Shaoguan.The effects of different integrated water and fertilizer patterns on growth process,agronomic characters,photosynthetic characters,curing characters,key enzyme activities,economic characters and fertilizer utilization rate of flue-cured tobacco were studied,it provides theoretical basis for high yield and high quality of high quality tobacco leaves on sloping land.1、After the application of liquid fungal fertilizer to reduce the consumption of basic nutrients on smoky soil,without nitrogen reduction after the application of liquid fungal fertilizer（K1）,the effective phosphorus content increased significantly（123.71%）,nitrogen reduction 20%after the application of liquid fungal fertilizer（K3）on the whole potassium consumption is low.K1 agronomic traits at the time of the clumping period were outstanding,but the later performance was average.Nitrogen reduction and application of liquid fungal fertilizer to regulate the development rhythm of tobacco plants,slowing down the pre-development,prolonging the root extension period,increasing the development time in the late growth period,and outstanding agronomic traits at maturity.2、The stomatal conductivity and cellular interstitial CO₂ concentration of the middle and upper leaves of K1 and K3 are significantly lower,indicating that the net photosynthetic rate decreases due to stomatal factors,while the photosynthetic properties of K2 have excellent performance.The follow-up application of liquid fungal fertilizer can improve the photochemical quenching and non-photochemical quenching coefficients of leaves and improve the photosynthetic activity and photoprotective ability of roasted smoke,but the maximum photosynthetic potential is basically the same.Trace application of liquid fungal fertilizer increased the content of malondialdehyde in the dome period,decreased the amylase activity of the upper leaves at 65-80 days,while delaying the decline of the nitrate reductase activity of the upper leaves,accelerated the decline of the nitrate reductase activity of the central leaves,while the starch content at 50-65 days increment is larger,at 65-80 days reduction is smaller,and increased the total sugar accumulation of the upper leaves at 65-80days.The activity of antioxidant system enzymes in K1 and K2 was significantly reduced in the dome period,but the activity of nitrate reductase and antioxidant system enzymes in liquid fertilizer（K3）was high with 20%nitrogen reduction,root vigor was significantly high,leaf senescence was delayed,metabolism was vigorous,and parietal leaf opening was too large.3、K1 and K3 have unstable water loss rate and high water loss during baking,excessive fluctuation of amylase activity,large amount of pre-degradation of starch,easy to bake leaves are not bakeable,K2 has more stable water loss rate and amylase activity during baking,less fluctuation of sugar metabolism rate,excellent baking characteristics.4、After the application of liquid fungal fertilizer to reduce the total sugar and starch content of tobacco leaves after baking,increase the ratio of two sugars,improve the petroleum ether content.The total nitrogen content of different treatments was less than 2.5%,and the nicotine content was around 1.5%.The glycobase ratio of the upper leaves was around 7 in 2018,but was greater than 10 in 2019.The K2 glycobase ratio of 10%nitrogen reduction in the two-year trial was smaller,and the nitrogen-base ratio of the upper leaves was less than 1.Through the nitrogen reduction of liquid fungal fertilizer,the yield and output value can be increased,of which the yield and output value at 10%nitrogen reduction was increased by 14.94%and13.35%in 2018,and 7.80%and 26.23%in 2019.The nitrogen fertilizer uptake rate of K3 in the two-year trial was 47.94%and 52.56%,an increase of 19.10%and 13.66%respectively.The performance of CK without nitrogen reduction was basically the same as that of CK.At 10%nitrogen reduction,the performance was high quality and suitable for production,the chemical composition of the tobacco leaves after roasting was more harmonized,the utilization rate of nitrogen fertilizer was improved,and the economic efficiency of slope roasted tobacco was improved;at 20%nitrogen reduction,carbon metabolism was vigorous at maturity,the top leaf was too large,and the roasting characteristics were average.