Effects Of High-carbon Basal Fertilizers Combined With Nitrogen Reduction On Soil Microbial Diversity And Tobacco Quality Of Tabacco-growing Soil In Fengdu Area

This experiment based on fengdu field trial,aiming to improve the industrial usability of fengdu tobacco and yunyan brands,in 2020～2021,to study the different dosage of high carbon based repair soil fertilizer with nitrogen fertilizer NPK in fengdu planting of tobacco soil and tobacco leaf quality and the influence of medium resistance.To find out the most suitable high-carbon basal fertilizers and nitrogen reduction ratio,for enriching the soil fertility,high quality,so as to provide basis and direction.The experiment took yunyan 116 as the main material and set up 6 treatments.CK:conventional fertilization of 111.00 kg/hm2 pure nitrogen,T1:high-carbon basal fertilizer 450 kg/hm2+99.90 kg/hm2 pure nitrogen(10%reduction in nitrogen),T2:high-carbon basal fertilizer 600 kg/hm2+94.35 kg/hm2 pure nitrogen(15%reduction in nitrogen),T3:high-carbon basal fertilizer 750 kg/hm2+88.80 kg/hm2 pure nitrogen(20%reduction in nitrogen),T4:high-carbon basal fertilizer 900 kg/hm2+83.25 kg/hm2 pure nitrogen(25%reduction in nitrogen),T5:high-carbon basal fertilizer 1050 kg/hm2+77.70 kg/hm2 pure nitrogen(30%reduction in nitrogen).The results were as follows:1.high-carbon basal fertilizers combined with nitrogen reduction on soil propertiesHigh-carbon basal fertilizers combined with nitrogen reduction could improve soil nutrient content and soil pH,and has a good effect on soil acidity improvement for tobacco planting in fengdu.At 90 d after transplantion,the T5 increased soil pH,which was 1.25 units higher than the control.High-carbon basal fertilizers combined with nitrogen reduction significantly increased the soil available N in the key growth period of tobacco(60 d after transplantion),at 60 d and 90 d after transplantion,T3 increased by 26.74%and 47.06%compared with the control.High-carbon basal fertilizers combined with nitrogen reduction significantly increased the soil available K content in the later growth stage of tobacco,at 105 d after transplantion,T4 increased by 56.50%compared with the control.T5 increased soil C/N,and decreased soil TN and TS content.2.Effects of High-carbon basal fertilizers combined with nitrogen reduction on soil microbial diversityThis study used 16S rRNA and ITS high-throughput sequencing technology to analyze soil microbial diversity.These results showed that:High-carbon basal fertilizer combined with nitrogen reduced could improve bacteria diversity in tobacco growing soil.Proteobacteria,Actinobacteria,Acidobacteria,Bacteroidetes,Gemmatimonadetes,Firmicutes is the dominant group in the composition of bacterial communities.At the phylum levels,high-carbon basal fertilizers combined with nitrogen reduction increased the relative abundance of Proteobacteria and Bacteroidetes,and decreased the relative abundance of Acidobacteria.At the genus levels,at 30 and 60 d after transplantation,T5 increased the relative abundance of Sphingomonas and Pseudarthrobacter.At 60 d after transplantation,T5 decreased the relative abundance of Rhodanobacter.ITS sequencing results showed that:Ascomycota,Zygomycota,Basidiomycota,Chytridiomycota is the dominant group in the composition of fungal communities.At phyluml level,at 30 days after transplant on,the relative abundance of Ascomycota increased of T3,which was 35.13%higher than that of the control.At 90 d after transplantation,high-carbon basal fertilizer combined with nitrogen reduced the relative abundance of Basidiomycota and Chytridiomycota,T5 was 35.02%and 7.55%lower than that of the control.At the genus levels,high-carbon basal fertilizers combined with nitrogen reduction increased the relative abundance of biocontrol bacteria(Penicillium)and decreased the relative abundance of pathogenic bacteria(Fusarium).According to redundancy analysis,high-carbon basal fertilizers combined with nitrogen reduction could affect soil microbial community structure by affecting soil nutrient content.Among them,available P,TN,available N and pH were the main reasons for the differences in phylum level of bacterial community structure in Fengdu tobacco-growing soils.Available N,available P,C/N and pH were the main reasons for the differences in phylum level of fungal community structure in Fengdu tobacco-growing soils.3.Effects of high-carbon basal fertilizer combined with nitrogen on growth and development of tobacco plantshigh-carbon basal fertilizer combined with nitrogen promoted the development of tobacco roots,and reduce the incidence and disease index of tobacco mosaic disease.At 60 d after transplantion,T2 and T3 was significantly increased root fresh weight,which were 55.50%and 62.08%higher than that of the control.At 60 days after transplantion,the incidence and disease index of high-carbon basal fertilizer combined with nitrogen were lower than those of the control,which T2,T3 and T5 were significantly reduced,and the incidence rates were reduced by 40.64%,41.60%and 59.36%,respectively.4.Effects of high-carbon basal fertilizer combined with nitrogen on appearance quality of flue-cured tobacco leavesEffects of high-carbon basal fertilizer combined with nitrogen on the appearance quality of flue-cured tobacco.The results showed that high-carbon basal fertilizer combined with nitrogen improved the leaf structure,oil content and gloss of B2F grade flue-cured tobacco,and the T1,T2,T3 and T4 treatments were better than the control.The application of high-carbon basal fertilizer combined with nitrogen improved the color and oil content of C3F grade flue-cured tobacco,and the T3 and T4 treatments were better than the control.5.Effects of high-carbon basal fertilizer combined with nitrogen on contents of conventional chemical constituents of flue-cured tobacco leavesHigh-carbon basal fertilizer combined with nitrogen increased the total sugar and reduced sugar contents of B2F and C3F grades of flue-cured tobacco leaves.T2 and T3 treatments increased the contents of nicotine and total nitrogen in cured tobacco leaves of B2F and C3F grades.The nicotine content increased first and then decreased with the increase of high carbon basal fertilizer and nitrogen reduction ratio,the trend peaked at T3 treatment.The potassium-to-chlorine ratio of cured tobacco leaves in each treatment was greater than 4,and the tobacco leaves had better combustibility.6.Effects of high-carbon basal fertilizer combined with nitrogen on Contents of neutral aroma constituents of flue-cured tobacco leavesHigh-carbon basal fertilizer combined with nitrogen increased the content and types of neutral aroma substances in cured tobacco leaves.In the middle leaves,the total amount of aroma substances increased by 11.79%,6.92%,18.24%and 6.88%in T2,T3,T4 and T5 treatments,respectively.In the upper leaves,T1,T2,T3,T4 and T5 treatments increased by 17.12%,16.42%,22.71%,11.79%and 8.57%,respectively.Among them,the total amount of carotenoid degradation products,the contents of solanone and neophytadiene in cured tobacco leaves were increased to varying degrees.7.Effect high-carbon basal fertilizers combined with nitrogen reductionon on the sensory quality of flue-cured tobacco leavesHigh-carbon basal fertilizer combined with nitrogen improved the sensory quality evaluation of the middle and upper leaves of flue-cured tobacco.The aroma quality,aroma quantity,concentration,miscellaneous smell and aftertaste of the middle leaves treated with high-carbon basal fertilizer combined with nitrogen were better than those of the control.Among them,T2,T3 and T4 treatments significantly improved the sensory quality scores of middle-cured tobacco leaves by 1.43%,1.29%and 1.60%respectively compared with the control.In the upper leaves,the aroma quality,aroma quantity,concentration,energy,and grayness of the upper leaves treated with high-carbon basal fertilizer combined with nitrogen were better than those of the control.Among them,T2,T3,and T4 treatments significantly improved the sensory quality scores of upper-cured tobacco leaves,which were 1.50%,2.03%,and 1.65%higher than the control,respectively.8.Effect high-carbon basal fertilizers combined with nitrogen reductionon on Economic traits of flue-cured tobacco leaveshigh-carbon basal fertilizers combined with nitrogen reductionon increased the yield,output value,average price and proportion of premium tobacco.Among them,T1,T2,T3 treatments were higher than the control in all indicators,and the income per hectare increased by 1831.80 yuan,3997.05 yuan and 2498.40 yuan respectively.The output value per mu and the proportion of high-quality tobacco in T2 treatment were the highest,which were increased by 11.47%and 10%respectively compared with the control;the yield of T3 treatment was the highest,which was increased by 7.76%compared with the control.The effects of T2 and T3 treatments on the economic indicators of cured tobacco leaves were better,and the value of tobacco leaves was higher.In 2021,the average income of flue-cured tobacco leaves treated with T3 increased by 2,587.65 yuan per hectare,and the results of the study in 2021 and 2020 were consistent.To sum up,the application of high-carbon basal fertilizers to reduce nitrogen in the Fengdu tobacco-growing area of Chongqing increased soil nutrient content and soil pH,and had a good effect on the acidity improvement of tobacco-growing soil in Fengdu.It was helpful to improve the microbial community structure.Improve the chemical coordination of cured tobacco leaves,increase the content of neutral aroma substances in cured tobacco leaves,and improve the yield and quality of tobacco leaves.The application of high-carbon basal fertilizer 750 kg/hm2+88.80 kg/hm2 pure nitrogen had the best effect on improving the soil properties of tobacco planting and improving the yield and quality of tobacco leaves.