Variation Dynamics of Total Nitrogen and Nicotine of Burley Tobacco at Various Growing Stages under Different Nitrogen Nutrition Levels

[Objective] This study aimed to investigate the variation dynamics of total nitrogen and nicotine of burtey tobacco at various growing stages under different ni- trogen nutrition levels to provide reference for optimizing fertilization technologies for burley tobacco. [Method] Fresh burley tobacco leaves were collected at various growing stages and dried to measure the content of total nitrogen, protein and nico- tine by using INTEGRAL automated chemical analyzer and analyze the correlation with nitrogen application level. [Result] Regardless of the nitrogen application level, the content of total nitrogen and protein showed a downward trend since root ex- tending stage and reached the minimum at mature stage; the content of nicotine showed an upward trend since early vigorous growing stage and increased to the maximum at mature stage; the content of total nitrogen, protein and nicotine all in- creased after air curing; the content of total nitrogen, protein and nicotine showed positive correlation with nitrogen application level, while total nitrogen/nicotine was negatively correlated. The results indicate that nitrogen level is closely related to the total nitrogen and nicotine of burley tobacco at growing period and post-air curing, rational application of nitrogen is an important measure to regulate the content of total nitrogen and nicotine of tobacco. [Conclusion] This study provides scientific ba- sis for rational fertilization of burley tobacco.

Characteristics of Soil Organic Carbon, Total Nitrogen, and C/N Ratio in Chinese Apple Orchards

Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.

Residue management induced changes in soil organic carbon and total nitrogen under different tillage practices in the North China Plain

Crop residue retention has been considered a practicable strategy to improve soil organic carbon(SOC)and total nitrogen(TN),but the effectiveness of residue retention might be different under varied tillage practices.To evaluate the effects of residue management on the distribution and stocks of SOC and TN under different tillage practices,a bifactorial experiment with three levels for tillage practices(no-tillage,rotary tillage,and conventional tillage)and two levels for residue managements(residue retention and residue removal)was conducted in the North China Plain(NCP).Results showed that after a short experimental duration(3–4 years),concentrations of SOC and TN in the 0–10 cm layer were higher under no-tillage than under conventional tillage,no matter whether crop residues were retained or not.Residue retention increased SOC and TN concentrations in the upper layers of soil to some degree for all tillage practices,as compared with residue removal,with the greatest increment of SOC concentration occurred in the 0–10 cm layer under rotary tillage,but in the 10–30 cm layer under conventional tillage.The stocks of SOC in the 0–50 cm depth increased from 49.89 Mg ha–1 with residue removal to 53.03 Mg ha–1 with residue retention.However,no-tillage did not increase SOC stock to a depth of 50 cm relative to conventional tillage,and increased only by 5.35%as compared with rotary tillage.Thus,residue retention may contribute more towards SOC sequestration than no-tillage.Furthermore,the combination between residue retention and no-tillage has the greatest advantage in enhancing SOC and TN in the NCP region.

Characteristics of soil organic carbon andtotal nitrogen storages for differentland-use types in Central Yunnan Plateau

Two-factor analysis of variance and redundancy analysis were used to analyze the characte-ristics of soil organic carbon total nitrogen storage in garden land,forestland,grassland,farmland,and bare land in the Dachunhe watershed of Jinning District,Kunming City,Yunnan Province,China.The effects of the soil organic carbon,total nitrogen stratification ratio,soil physical and chemical factors on the storage characteristics of organic carbon and total nitrogen of different land-use types were analyzed.The results show that the rates of carbon and nitrogen stratification in soil from 0-20 cm and 40-60 cm of the same land-use types differed are statistically significant(P<0.05).The organic carbon and total nitrogen stratification ratio SR1 of garden land soil are 38.5%and 25.3%,respectively,which are higher than SR^(2).The soil organic carbon and total nitrogen stratification ratio SR^(2) of different land-use types are greater than SR1.There are statistically significant differences in the SR^(2) soil organic carbon and total nitrogen stratification ratios(P<0.05).Soil organic carbon and total nitrogen storage of diffe-rent land-use types gradually decrease with increasing soil depth,with the maximum soil organic carbon and total nitrogen storage in the 0-20 cm soil layer.Soil organic carbon and total nitrogen sto-rage at the same soil depth are significantly different(P<0.05).Soil organic carbon and total nitrogen storage in the garden land are greater than those in the other land-use types.Soil organic carbon and total nitrogen storage in 0-20 cm garden land are 4.96 and 3.19 times than those in bare land,respectively;soil organic carbon and total nitrogen storage are explained by 93.66%and 1.53%in redundancy analysis RDA1 and RDA2,respectively.All physicochemical factors except Available Phosphorus and pH are statistically significance with carbon and nitrogen storage(P<0.05).Soil cationic exchange capacity,Available Phosphorus,C/N ratio,and Moisture Content are positively correlated with organic carbon and total nitrogen storage.In contrast,soil Bulk Density is negatively correlated with organic carbon storage and total nitrogen storage.Available Phosphorus,C/N ratio,and Moisture Content are the main factors promoting soil organic carbon and total nitrogen accumulation.

The enrichments of organic matter and total nitrogen in sediment as affected by relavant factors

Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.

Effect of Different Fertilization Patterns on Carbon and Nitrogen Components of Tobacco Topsoil

In order to explore the fertilizing ways and dynamic changes of soil carbon and nitrogen in the main producing areas of tobacco in Guizhou,research was conducted to study the variations of dissolved organic carbon and nitrogen,total organic carbon and nitrogen and their ratio of tobacco-topsoil in organic fertilization pattern and conventional cultivation pattern （No fertilizer as control） by pot experiment.The results were as follows：（1） The effects of different fertilization patterns on soil dissolved organic carbon and nitrogen and total organic carbon and nitrogen were significantly different.The content of DOC,DON,TOC and TON in tobaccotopsoil was decreased with the advancing of growth period in conventional fertilization pattern.In the conventional fertilization pattern,the accumulation of DOC and TOC was increased first and then decreased,and the accumulation of DON and TON was decreased first and then increased.（2） The TOC content at the different growing stage and DOC content at the middle and later stage of tobacco were significantly improved in organic fertilization patterns.The accumulation of DON and TON in the conventional fertilization pattern was significantly higher than those in the organic fertilizer pattern and control at the rosette stage and vigorous stage.In the harvest period,the content of DOC,DON,TOC and TON of tobacco-topsoil in the conventional fertilization and organic fertilization pattern was significantly higher than those in the control.（3）The DOC/DON ratio and the TOC/TiON ratio was increased gradually with the advancing of growth period in conventional fertilization pattern,but they were increased first and then decreased in the organic fertilization pattern and CK.The DOC/DON and TOC/TON ratio of tobacco-topsoil in different fertilization patterns was showed as Y J＞ CK＞ CG at the different growing stage.The experiment results revealed that：The organic fertilization pattern may improve significantly the accumulation of DOC,DON,TOC and TON of tobacco-topsoil at the middle and later stage and the DOC/DON and TOC/TON ratio at the different growth stage.It contributed to the continuous and balanced supply of nutrients at the middle and later stage of tobacco and the soil fertility.

城郊结合带流域水体富营养化特征及来源分析

选取南昌市前湖水系为研究对象,运用对数型幂函数普遍适用的指数公式,对其进行富营养化程度评估。同时,进行相关性分析探究水质环境因素与水体富养化水平之间的相互关系。研究结果显示:前湖水系中高锰酸盐指数、氨氮、总磷、总氮、五日生化需氧量5种污染物含量呈现显著的空间分布特征;前湖水系水体富营养化指数(V E)介于51.34~70.52,均呈现水体富营养化,TN、TP与富营养化的相关性分别为0.917和0.912,表明氮磷是导致水体富营养化的主因;氮磷比平均值为19.57,污水处理厂排污、城区及周边的污染汇入等是南昌市前湖水系水体污染物的主要来源。对前湖水系进行研究,旨在提高对城郊结合部水环境的关注度。

江河源冻土区土壤碳氮空间分布特征及其影响因素

江河源区是我国高寒生态安全屏障的重要区域,冻土的长期存在使其形成低温冻结环境,弱化了土壤微生物活性,抑制了土壤有机质的矿化过程,因而其近地表浅层土壤碳氮含量高。然而,土壤碳氮含量对不同冻土分区和环境因素响应的空间分异规律尚不清楚。为此,针对江河源4个不同冻土区(季节冻土区、岛状多年冻土区、不连续多年冻土区、片状连续多年冻土区)共11个样点进行植被样方调查、土壤分层采样。在分析碳氮含量的基础上,探讨了年均地温(MAGT)、活动层厚度(ALT)、海拔(ASL)、土壤深度(SD)、植被特征及土壤pH对土壤有机碳(SOC)、全氮(TN)、碳氮比(C/N)的影响。结果表明:(1)SOC、TN、C/N在片状连续多年冻土区最高,在季节冻土区最低,且与年均地温负相关,和海拔正相关;(2)江河源区SOC、TN、C/N随土壤深度的增加而降低,自表层至40cm深度整体下降幅度分别为58.45%、36.96%、17.01%;(3)SOC、TN、C/N与植被覆盖度(FVC)显著正相关(P≤0.05),与土壤pH值显著负相关(P≤0.01);(4)冗余分析表明,土壤pH、MAGT、ALT、SD、FVC是影响江河源区SOC、TN、C/N空间分布的关键因素。研究结果可为厘清气候趋暖条件下江河源区土壤碳氮空间分异规律及多年冻土热稳定性对土壤碳氮排放的影响提供科学基础,同时也有助于预测多年冻土区土壤碳氮空间变化。

柑橘大豆间作对土壤团聚体结构及其有机碳、氮分布的影响

探讨柑橘大豆不同间作年限下土壤团聚体结构及有机碳、氮分布差异,旨在为果园土壤改良提供参考。通过田间定位试验设置清耕区(CK)、柑橘间作大豆1年(T1)、柑橘间作大豆2年(T2)和柑橘间作大豆3年(T3)4个处理,测定土壤团聚体组成、稳定性、有机碳和全氮等指标。结果表明:①与清耕柑橘园相比,柑橘间作大豆的土壤>0.25 mm大团聚体含量提高了19.58%~22.29%;②柑橘间作大豆的土壤团聚体稳定性特征表现为:T3>T2>T1>CK;③团聚体粒径中的有机碳和全氮含量表现为>5 mm粒径最高,<0.25 mm粒径含量最低,柑橘间作大豆的土壤C/N值较清耕区提高了1.16倍~1.19倍;④土壤团聚体组成与团聚体有机碳和全氮含量的相关性显著,RDA分别解释99.32%和94.99%的差异信息,其中>5、5~2和0.5~0.25 mm粒径土壤团聚体是影响土壤有机碳和全氮含量变化的主要环境因子。总体而言,柑橘园行间间作大豆可增加土壤肥力,改善土壤团聚体结构,是一种可持续农业发展模式。

高碳基肥减氮施用对植烟土壤总碳、总氮和真菌群落结构的影响

本研究采用田间试验法,以常规施肥(纯氮111 kg·hm^(-2))为对照(GCK),设置高碳基肥450 kg·hm^(-2)+减氮10%(G3)、高碳基肥750 kg·hm^(-2)+减氮20%(G5)和高碳基肥1050 kg·hm^(-2)+减氮30%(G7)共4个处理,研究其对植烟土壤总碳、总氮含量的影响,并采用ITS测序技术分析烟田土壤真菌群落结构及其与土壤总碳和总氮的关系。结果表明:(1)高碳基肥减氮施用处理G7提高植烟土壤总碳含量和碳氮比(移栽后60、90 d),降低土壤总氮含量(移栽后60、90 d)。(2)高碳基肥减氮施用处理G3显著提高土壤真菌丰富度(移栽后30、90 d)。(3)高碳基肥减氮施用改变了真菌的群落结构,在门水平上提高了接合菌门(Zygomycota)相对丰度(移栽后60 d),降低了子囊菌门(Ascomycota)相对丰度;在属水平上提高了木霉属(Trichoderma)相对丰度,降低了镰刀菌属(Fusarium)相对丰度(移栽后60 d)。(4)高碳基肥减氮施用通过影响土壤总碳、总氮含量和碳氮比改变其真菌多样性和群落结构。本试验条件下,每公顷施用高碳基肥1050 kg+纯氮77.7 kg(G7)对植烟土壤总碳、总氮、碳氮比以及真菌群落结构影响较大。

水稻秸秆炭施用对水稻土团聚体稳定性及其碳氮分布的影响

[目的]水稻长期种植过程中大量化肥施用导致土壤结构变差,研究不同用量水稻秸秆生物炭和化肥配施对水稻土结构和碳、氮分布的影响,探索稻田优化施肥管理方式。[方法]水稻田间试验在浙江衢州进行,试验设不施肥对照(CK)、常规施肥处理(NPK)以及常规施肥基础上添加22.5 t/hm^(2)(NPK+1%B)、45 t/hm(NPK+2%B)和90 t/hm^(2)(NPK+4%B)水稻秸秆炭处理,共5个处理。水稻收获后采集0-20 cm土层样品,测定土壤及不同粒级团聚体(>2、0.25~2、0.053~0.25和<0.053 mm)的有机碳和全氮含量,评价团聚体的稳定性。[结果]与NPK处理相比,施用水稻秸秆炭4年后,土壤>0.25 mm粒级团聚体含量提高了2.43%~7.99%,<0.25 mm粒级团聚体含量降低了2.93%~9.63%,土壤有机碳和全氮含量分别提高了16.40%~45.16%和14.67%~36.69%,各指标的变幅均以NPK+4%B处理最大。与NPK处理相比,秸秆炭处理土壤中>2 mm粒级团聚体中的有机碳和全氮含量分别提高了23.96%~70.87%和19.44%~47.56%,0.25~2 mm粒级团聚体中分别提高了21.87%~49.27%和17.18%~37.47%,增幅均以NPK+4%B处理最高,而0.053~0.25和<0.053 mm粒级团聚体中的有机碳和全氮含量无显著差异(P>0.05),说明施用水稻秸秆炭4年后,增加的土壤有机碳和全氮主要积累在>0.25 mm粒级团聚体中。与NPK处理相比,秸秆炭处理水稻土C/N值提高了2.40%~5.69%,但各处理间差异不显著,而4个粒级团聚体的土壤C/N值均显著提升,且均以NPK+4%B处理提高效果最好。此外,施用水稻秸秆炭提高了>2和0.25~2 mm粒级团聚体的碳、氮贡献率6.54%~17.43%、3.67%~7.28%和5.16%~11.55%、0.57%~1.83%,降低了0.053~0.25和<0.053 mm粒级团聚体的碳、氮贡献率7.25%~29.27%、15.93%~33.68%和10.26%~26.80%、12.61%~30.78%(P<0.05)。[结论]施用水稻秸秆炭能够迅速显著提高水稻土有机碳和全氮含量,增加>0.25 mm粒级团聚体质量占比,提高>2 mm粒级团聚体中有机碳的贡献率,降低<0.25 mm粒级团聚体中有机碳和全氮贡献率,且其影响幅度与水稻秸秆炭施用量呈正比。由此可见,施用水稻秸秆炭能在一定程度上改善水稻土结构,提高水稻土碳、氮固持潜力,对保证水稻土结构稳定性和维持水稻持续高产具有重要意义。

巢湖及入湖河流氮素变化特征分析

基于安徽省地表水环境质量监测网监测数据,研究了2013—2022年巢湖主要入湖河流和湖体氮素变化特征。结果表明:10年来,主要入湖河流和湖体总氮年均值范围分别为2.93~6.52 mg/L、1.18~1.72mg/L,氨氮年均值范围分别为0.49~4.98mg/L、0.10~0.44mg/L,入湖河流总氮、氨氮浓度均远高于湖泊。入湖河流和湖体氮素呈现出较为相似的年际变化、季节变化和月度变化特征,总氮、氨氮浓度均冬、春季高,夏、秋季低。巢湖入湖河流新旧污染同时存在。对于Ⅴ类和劣Ⅴ类等污染严重的水体,氨氮占比较高;水质较好的水体,氨氮占比较低。

白肋烟不同品种和叶位叶片生物碱和总氮含量的差异

于2007年设置品种试验并在不同产地取样对我国白肋烟主要品种各叶位烟叶的生物碱和总氮含量进行了分析测定,结果表明,达白1号和TN90生物碱含量相对较为适宜,生物碱组成合理,降烟碱含量较低,烟碱转化率低于6%的国际限制性标准。鄂烟1号烟碱含量相对适宜,但总生物碱含量偏高,降烟碱含量和烟碱转化率较高。宣汉-5和达所24总生物碱水平较高,但烟碱转化导致烟碱含量偏低,降烟碱含量增高,烟碱转化率大幅度超过限量标准,且下部叶和脚叶氮碱比过高。不同叶位烟叶生物碱含量有显著差异,一般表现为随叶位的升高烟碱和总生物碱含量增高,但顶叶和上部叶差别较小。我国白肋烟部位间烟碱含量差异较大,上部叶烟碱含量偏高是突出问题。随叶位升高烟叶总氮含量有增加趋势,氮碱比显著下降。同一品种在不同产地生物碱含量和总氮含量有一定差异。

豫中烤烟烟碱和总氮含量与中性香气成分含量的关系

在对浓香型烤烟产区27个上二棚烟叶样品分析测定的基础上,研究了烟碱和总氮含量与烟叶中性香气成分含量的关系。结果表明,烟叶烟碱和总氮含量与类胡萝卜素类香气成分含量呈显著的二次曲线相关关系,在烟碱含量为3.82%时总类胡萝卜素类香气物质含量最高,在烟碱含量1.28%~3.92%范围内巨豆三烯酮2、巨豆三烯酮4、法尼基丙酮、二氢猕猴桃内酯和香叶基丙酮含量随烟碱含量的增高呈持续增加趋势。西柏烷类降解产物茄酮含量与烟碱和总氮含量也呈极显著的二次曲线相关关系,但茄酮含量最大值分别出现在烟碱含量为2.62%,总氮含量为2.77%时,此后显著下降。糖和氨基酸棕色化反应产物仅个别成分与烟碱和总氮含量显著相关。芳香族氨基酸降解产物总量、新植二烯和中性挥发性物质总量与烟碱和总氮含量呈显著的二次曲线相关关系,在烟碱和总氮含量分别为2.89%和3.05%时中性挥发性物质总量出现最大值。

影响上部烟叶感官质量的主要化学成分分析

【目的】明确影响上部烟叶感官质量最主要的化学成分。【方法】测定国内外6个产地共107份上部烟叶样品主要化学成分,评价其感官质量,分析化学成分指标与感官质量总分的关系;对比分析了国内外主产烟区8032份上部烟叶样品的3项主要化学成分。【结果】①简单相关分析显示,总糖、还原糖含量与感官质量呈显著或极显著的正相关关系,总氮、烟碱含量与感官质量呈显著或极显著的负相关关系;②逐步回归和通径分析显示,影响上部烟叶感官质量的最主要化学成分为总氮、总糖、烟碱。③国内多数主产烟区上部烟叶总氮含量均高于国外上部烟叶,总糖、烟碱含量接近于或者高于国外上部烟叶。【结论】要提高上部烟叶感官质量,应着重控制总氮含量,协同控制烟碱含量和提高总糖含量。

不同晾房白肋烟晾制过程中生物碱和总氮含量的变化

采用5种晾房（竹笆涂泥晾房、美式全板晾房、黑膜夹草晾房、金黑膜晾房、黑膜推杆晾棚）和2种采收方式（半整株采收和摘叶采收）研究了白肋烟晾制过程中生物碱、总氮含量及氮碱比的交化。在烟叶晾制过程中，烟碱和总生物碱含量总体呈下降趋势，降烟碱、假木贼碱和新烟草碱变化相对较小。竹笆涂泥、美式全板、黑膜夹草3种方式烟碱含量的下降幅度相对较大，中部叶和上部叶下降幅度分别为17．6％-27．6％和16．5％～19．7％，晾制后烟叶生物碱含量和氮碱比较为适宜；而黑膜推竿晾制和全黑膜晾房的烟叶烟碱含量降低幅度较小，氮碱比偏小。摘叶采收烟叶烟碱含量较高，氮碱比较小，且在晾制过程中含量下降幅度较小，这与其失水干燥较快，调制过程较短有关。

种植海拔对烤烟石油醚提取物及常规化学成分的影响

为探讨种植海拔高度对烤烟烟叶品质的影响,测定了在相同的土壤基质、种植密度、施肥水平、施肥方案和农艺措施条件下于湘西北石门县与慈利县200～1200m海拔高度盆栽的烤烟品种新K326和云烟87初烤烟叶C3F的石油醚提取物总量、总烟碱、还原糖、总氮、氯和钾含量.结果表明:①海拔与烤烟石油醚提取物总量显著正相关(P＜0.05);②海拔与烤烟总烟碱及总氮含量负相关,新K326和云烟87分别达显著(P＜0.05)和极显著水平(P＜0.01);③海拔与烤烟还原糖和糖碱比值均正相关,新K326和云烟87分别达极显著(P＜0.01)和显著水平(P＜0.05);④海拔对初烤烟叶钾含量和氯含量均无明显影响.结论:适当提高烤烟种植的海拔高度,有利于提高烟叶的香气量,并使烟叶主要化学成分的含量更加协调,从而提高烟叶的可用性.

西北海拔高度对烤烟常规化学成份含量的影响

通过野外栽培试验、全自动化学流动分析测定法和火焰光度测定法,研究了湘西北慈利县与石门县海拔高度对烤烟常规化学成份含量的影响,主要结果是:1)烤烟总烟碱含量和总氮含量均与海拔高度呈极显著的负相关,而钾含量与海拔高度呈正相关.2)烤烟总糖含量与海拔高度间无明显的相关性,海拔高度对烤烟氯含量无影响.3)高海拔区域种植烤烟有利于降低烟叶的烟碱含量、提高烟叶的钾含量,从而提高烟叶的可用性与安全性.

FT-NIR光谱测定烟草中烟碱、总氮、总糖含量的模型研究

试验旨在研究应用近红外光谱技术快速测定烟草中烟碱、总氮、总糖含量的可行性.使用偏最小二乘法（PLS）为建模方法,选择4 030～9 000 cm-谱段,采用一阶导数和SG平滑滤波法进行光谱预处理,建立了烟草中烟碱、总氮、总糖的近红外预测模型.3种组分最佳PLS预测模型的相关系数r分别为0.993 2,0.963 5和0.9810,交叉检验的均方差（RMSECV）分别为0.076 7,0.077 2和0.984 0.考察了模型的精密度,并将近红外光谱技术与参考方法（YC/T161）相比较,用实际样品进行了验证.结果表明：所建模型精密度良好,两种方法测得值不存在显著性差异（P＜0.05）,近红外光谱技术可以准确地定量分析烟草中烟碱、总氮、总糖.

不同栽培条件对烤烟上部烟叶烟碱和总氮含量的影响

研究不同农艺措施对打顶后烤烟上部叶片烟碱与总氮含量的动态变化。结果表明,随着烤烟打顶后天数的增加,上部烟叶烟碱量增加而总氮量减少,施氮量与烟碱含量和总氮量呈正相关,而种植密度、留叶数与其呈负相关。