Organic nitrogen availability is increasingly recognized as a regulatory factor shaping plant metabolic organization beyond its nutritional role. This study investigates the regulatory function of exogenous glutamate (Glu) in Nicotiana tabacum L., focusing on its spatial compartmentalization between the apoplast and symplast and its role in carbon-nitrogen metabolic regulation. Using a method for separately extracting apoplastic and symplastic solutions, we analyzed the distribution of free amino acids in roots and shoots under different Glu supplies (0, 0.05, and 1 mM). Exogenous Glu was preferentially assimilated in the root symplast and rapidly converted into glutamine (Gln), which served as the dominant organic nitrogen form for long-distance transport via the xylem. In leaves, organic nitrogen accumulated mainly as amino acids in the apoplast, contributing to nitrogen buffering and compartment-specific partitioning. In roots, elevated Glu supply induced coordinated reprogramming of carbon-nitrogen metabolism, including activation of the gamma-aminobutyric acid (GABA) shunt, restructuring of the tricarboxylic acid cycle, and enhancement of jasmonate-and nicotine-associated secondary metabolism. Transcriptomic analyses further revealed Glu-dependent regulation of key genes involved in these processes. Collectively, these findings identify exogenous Glu as an important regulatory factor integrating organic nitrogen assimilation, metabolic reprogramming, and secondary metabolism.

Amino acid transport is essential for organic nitrogen acquisition and signaling in plants, yet the transporter-level mechanisms underlying glutamate (Glu) responses remain unclear, especially in polyploid crops. Here, we conducted a genome-wide identification and expression analysis of amino acid transporter (AAT) genes in allotetraploid tobacco (Nicotiana tabacum). We identified 182 AAT genes and classified them into 12 subfamilies based on phylogenetic relationships with Arabidopsis thaliana and rice (Oryza sativa). Chromosomal mapping revealed an uneven distribution with prominent tandem clusters, and duplicated gene pairs were predominantly under purifying selection, suggesting overall functional constraint after polyploidization. RNA-seq analysis showed that Glu triggers time- and dose-dependent transcriptional reprogramming of AAT genes, with substantially stronger and more coordinated responses in roots than in shoots. 23 AAT genes were identified as Glu-responsive candidates in roots, mainly from the LHT, AAP, and ProT subfamilies. Correlation-based network analysis further highlighted 22 transcription factors strongly associated with these transporters, including seven core hub regulators. qRT-PCR validation of five key Glu-responsive AAT genes confirmed the transcriptome data. Promoter analysis revealed enrichment of MYB-, bZIP/bHLH-, and WRKY-related motifs, along with hormone- and stress-responsive elements, supporting transcription factor–mediated regulation. Physiological and phenotypic analyses indicated that Glu treatment promoted carbon and nitrogen accumulation, increased shoot biomass and root-to-shoot ratio, while exerting minimal effects on leaf area and root morphology in tobacco seedlings. These results propose a regulatory framework linking Glu signaling to AAT expression in tobacco roots and provide candidate genes for improving organic nitrogen utilization, providing theoretical support and genetic resources for improving nitrogen use efficiency in polyploid crops.

【Objective】Climatic differences among transplanting dates directly affect tobacco plant growth, yield, and leaf quality. This study aims to determine the optimal transplanting time in potential tobacco-producing areas of Shandong Province, including Qingdao, Zibo, and Laiwu, to optimize climate resource utilization and improve leaf quality.【Method】From 2022 to 2023, transplanting date comparison trials were conducted in Qingdao, Zibo, and Laiwu, with three transplanting dates: Y1 (April 30), Y2 (May 10), and Y3 (May 20). Agronomic traits at the topping stage, chemical composition of C3F-grade cured leaves, sensory quality, and economic traits were comprehensively evaluated under different transplanting treatments. Regression analysis was performed using meteorological data to identify the optimal transplanting period.【Result】The transplanting period significantly affects agronomic traits of tobacco plants, such as plant height, effective leaf number, stem circumference, and leaf morphology, while also influencing the chemical composition of middle tobacco leaves, including reducing sugars, total sugars, nicotine, and the nitrogen-nicotine ratio, as well as sensory quality factors like aftertaste and offflavor. Overall, the Y2 transplanting period performed best in the three tobacco regions, with the healthiest tobacco plants, coordinated chemical composition, and highest economic benefits. Compared to the Y1 transplanting period, the Y2 transplanting period increased the output value per 667 m2 in the Jiaozhou, Yiyuan, and Laiwu tobacco regions by 14.94%, 7.51%, and 23.30%, respectively. Regression analysis results showed that the daily average temperature of the transplanting period corresponding to the highest sensory scores and output value per 667 m2 in the three tobacco regions was between 18 ℃ and 19℃. Specifically, the optimal transplanting temperatures when the output value per 667 m2 peaked in Jiaozhou, Yiyuan, and Laiwu were 18.20℃, 18.85℃, and 19.11℃, respectively, while the temperatures corresponding to the highest sensory scores were 18.34℃, 18.45℃, and 19.01℃, respectively. Further analysis of meteorological data found that although the conventional transplanting time in each production area is from late April to early May, with temperatures typically reaching 15℃, there is still a certain gap compared to the optimal temperature for tobacco plant growth. Therefore, appropriately delaying the transplanting time to better align with the optimal temperature range could improve the growing environment of tobacco plants, enhance leaf yield and quality.【Conclusion】The optimal transplanting periods were identified as May 17-20 for Jiaozhou, May 13-16 for Yiyuan, and May 12-16 for Laiwu.

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Leaf angle (LA) is a key plant architectural trait contributing to crop yield. The chemical 2,4-epibrassinolide (EBR) is a bioactive form of brassinosteroids (BRs) and plays a significant role in influencing plant architecture, including regulating the LA. To investigate the effects of EBR on LA in tobacco seedlings, we histochemically and molecularly characterized changes in LA in response to treatment with EBR at two different concentrations, T1 (1 × 10 −8 mol/L) and T2 (1 × 10 −5 mol/L). Compared with control plants, EBR significantly increased the LA in T1 and T2 by 38.6% and 37.3%, respectively, which likely resulted from increased cell areas of 95.2% and 185%, respectively, and inhibited cell division with the number of cells per unit area experiencing 16.4% and 41.8% decreases, respectively. The relative expression levels of NtBIN2 , NtEXPA28 , and NtCYCD1 genes were consistently correlated with the size of the LA. By analyzing the expression of the auxin (IAA), gibberellin (GA), and brassinosteroid (BR) biosynthesis and signaling pathways, the coordinated relationship of these hormones were evaluated. A positive correlation between EBR concentration and the expression of IAA biosynthesis ( NtYUCCA8 ), GA biosynthesis ( NtGA20 ), BR signaling ( NtBRI1 , NtBES1 ), and IAA signaling ( NtGH3.2 and NtLC3 ) pathway related genes was observed, while a negative correlation was observed for the expression of cell cycle regulating genes ( NtCYCD2 , NtCYCD3 , and NtCYCD5 ). We also found that Cyclin, GA20, BRI1 and LC3 were more likely involved in regulating LA formation in tobacco. The findings of this study expand our knowledge of how plant architectural features such as LA are regulated at the molecular level and provides potential gene targets for genetic engineering or breeding efforts aimed at improving crop productivity and yields.

The difference between photosynthesis on the two leaf sides (dorsoventral asymmetry) of photosynthesis is important for light-use patterns, but the asymmetry is environment dependent. Its role in photosynthetic regulation has been intensively studied, but little is known about the impacts of direct and diffuse light on the asymmetry. Because of the current changing fraction of diffuse light in sky radiation, this study investigated the dorsoventral asymmetry of photosynthetic traits under direct and diffuse light conditions in an important food and energy crop, Sorghum bicolor L . A unique method was used to investigate the specific gas exchange of each leaf surface. Anatomical and morphological traits were different between the two surfaces of sorghum leaves, which might result in photosynthetic asymmetry. The variations in photosynthetic rates and stomatal conductance were significant between the two surfaces in direct and diffuse light, but the degree of dorsoventral asymmetry decreased in diffuse light. The integrated P N and G s of the adaxial illumination were significantly higher than that of abaxial illumination both in direct and diffuse light in sorghum leaves, but the ASI of the integrated P N was 2.83 in direct light, while significantly dropped to 1.69 in diffuse light. Significant morphological differences between the two surfaces might cause photosynthetic asymmetry in the sorghum leaves. The variations of specific gas exchange were significant between direct and diffuse light, including in the incident and self-transmitted light. Compared with direct light, diffuse light reduced the stomatal sensitivity, with the degree of decline being greater in the adaxial surface, which caused weak dorsoventral asymmetry in photosynthesis. The specific photosynthetic characteristics in sorghum leaves varied obviously in direct and diffuse light, including in the incident and self-transmitted light, which contributed to the different overall gas exchange. Compared with direct light, the decline of stomatal sensitivity, which showed positive correlation with stomatal density, caused weakened dorsoventral asymmetry in photosynthesis in diffuse light. The findings provide new insights into dorsoventral asymmetry and the impact of diffuse light on photosynthesis in isobilateral leaves.

Plant phenotypic parameters provide key information in modern crop breeding. However, the rapid and accurate estimation of organ-scale phenotypic parameters remains a challenge. In this context, the present study proposed a novel methodology for the automatic quantification of the organ-scale parameters of field crops using the unmanned aerial vehicle (UAV) platform. First, a lightweight UAV was employed to capture the multi-view and high-resolution image sequences of field crops at an extremely-low flight altitude. Subsequently, based on these image sequences, point cloud reconstruction of the canopy was conducted. Next, the geometrical model of individual leaves was reconstructed using the modified Crust algorithm and optimized by abnormal facet elimination and leaf surface repair. Finally, individual leaf phenotypic parameters were calculated based on the reconstructed geometrical models. The method was evaluated by comparing the calculated parameters with actual measurements. The calculated values for leaf length, maximum leaf width, and leaf area were in good agreements with the measured values (maize: R2 > 0.97 for all parameters, RMSE for length, width, and leaf area was 2.6 cm, 0.4 cm, and 33.2 cm2, respectively; soybean: R2 > 0.85 for all parameters, RMSE for the counterparts was 0.3 cm, 0.5 cm, and 2.3 cm2, respectively; tobacco: R2 > 0.89 for all parameters, RMSE for the counterparts was 4.1 cm, 1.4 cm, and 42.6 cm2, respectively). The methodology based on extremely-low altitude UAV images has promising prospects in the crop breeding program for the automatic acquisition of fine organ-scale parameters with high efficiency.

Compared with sole nitrate (NO3−) or sole ammonium (NH4+) supply, mixed nitrogen (N) supply may promote growth of maize seedlings. Previous study suggested that mixed N supply not only increased photosynthesis rate, but also enhanced leaf growth by increasing auxin synthesis to build a large sink for C and N utilization. However, whether this process depends on N absorption is unknown. Here, maize seedlings were grown hydroponically with three N forms (NO3− only, 75/25 NO3−/NH4+ and NH4+ only). The study results suggested that maize growth rate and N content of shoots under mixed N supply was little different to that under sole NO3− supply at 0–3 d, but was higher than under sole NO3− supply at 6–9 d. 15N influx rate under mixed N supply was greater than under sole NO3− or NH4+ supply at 6–9 d, although NO3− and NH4+ influx under mixed N supply were reduced compared to sole NO3− and NH4+ supply, respectively. qRT-PCR determination suggested that the increased N absorption under mixed N supply may be related to the higher expression of NO3− transporters in roots, such as ZmNRT1.1A, ZmNRT1.1B, ZmNRT1.1C, ZmNRT1.2 and ZmNRT1.3, or NH4+ absorption transporters, such as ZmAMT1.1A, especially the latter. Furthermore, plants had higher nitrate reductase (NR) glutamine synthase (GS) activity and amino acid content under mixed N supply than when under sole NO3− supply. The experiments with inhibitors of NR reductase and GS synthase further confirmed that N assimilation ability under mixed N supply was necessary to promote maize growth, especially for the reduction of NO3− by NR reductase. This research suggested that the increased processes of NO3− and NH4+ assimilation by improving N-absorption ability of roots under mixed N supply may be the main driving force to increase maize growth.

Sugars are the primary products of photosynthesis and play multiple roles in plants. Although sugars are usually considered to be the building blocks of energy storage and carbon transport molecules, they have also gradually come to be acknowledged as signaling molecules that can initiate senescence. Senescence is an active and essential process that occurs at the last developmental stage and corresponds to programmed degradation of: cells, tissues, organs, and entire organisms. It is a complex process involving: numerous biochemical changes, transporters, genes, and transcription factors. The process is controlled by multiple developmental signals, among which sugar signals are considered to play a vital role; however, the regulatory pathways involved are not fully understood. The dynamic mechanistic framework of sugar accumulation has an inconsistent effect on senescence through the sugar signaling pathway. Key metabolizing enzymes produce different sugar signals in response to the onset of senescence. Diverse sugar signal transduction pathways and a variety of sugar sensors are involved in controlling leaf senescence. This review highlights the processes underlying initiation of sugar signaling and crosstalk between sugars and hormones signal transduction pathways affecting leaf senescence. This summary of the state of current knowledge across different plants aids in filling knowledge gaps and raises key questions that remain to be answered with respect to regulation of leaf senescence by sugar signaling pathways.

为分析山东烟叶感官质量与物理化学指标的相关性,解析烟叶品质的化学基础和物理标识,采集典型中部和上部烟叶样品,通过感官质量评价、理化检测和数理统计分析,对烟叶叶位、地域分布差异进行了比较.结果表明,山东省上中部烟叶物理指标总体适宜,化学成分总体相对协调,感官质量总体较好,地域分布差异显著.中部烟叶在适宜范围内指标的比例高于上部烟叶.感官质量评价指标与化学成分和物理指标进行典型相关分析,分别得到3对和2对显著性典型变量,对典型变量影响较大的感官质量评价指标有杂气、余味、香气质,影响较大的化学成分指标为还原糖、总糖、两糖比、氯、总氮和烟碱,影响较大的物理指标为叶宽、单叶重、叶片厚度、叶面密度和叶长.杂气与钾氯比成显著正相关,与氯、半纤维素成显著或极显著负相关;余味与钙、氮碱比、钾氯比、叶宽、含梗率成显著或极显著正相关,与淀粉、烟碱、钠、硫、氯、两糖比、叶片厚度、叶面密度成显著或极显著负相关;香气质与钙、钾氯比、叶宽、含梗率成极显著正相关,与总氮、烟碱、钠、氯、两糖比、叶片厚度、叶面密度成显著或极显著负相关.

为准确模拟烟草叶片生长发育进程,实现烟叶精准可控生产,连续两年设置不同移栽期田间对比试验,利用Richards方程建立基于不同尺度的烟草下、中、上部叶面积变化动态模型,并分析不同模型的模拟精度.结果表明,烟草各部位叶片叶面积变化动态模型均符合典型"S"型生长曲线特征,有效积温模型对下、中部叶片生长的模拟效果优于生长时间模型,而对上部叶片生长的模拟效果较差;温光效应模型对各部位叶片不同条件下生长进程的模拟精度均高于有效积温模型与生长时间模型,具有更高的普适性;各部位叶片最终叶面积随移栽期推迟呈现先增加后降低的规律,下、中部叶片生长速率随移栽期推迟呈现加快规律,而不同移栽期上部叶的生长速率近似;推导获得各部位叶片缓增期、快增期、稳增期的温光效应值,为精准预测叶片生长提供参考.

Sugar is involved in initiating leaf senescence. However, its regulatory role, especially as a signal in the senescence process, is unclear. Therefore, this study was designed to illustrate how sugar stimulates the onset of leaf senescence and controls sugar homeostasis through the T6P-SnRK (sucrose non-fermenting (SNF)-related kinase) and HXK (hexokinase) signaling pathways. We used a leaf disc system detached from fully expanded leaves of Nicotiana tabacum cv. K326 and designed a time-course study (days 3, 5, 7, and 9) with exogenously gradient concentrations (0, 30, 60, 90, 120, and 150 mM) of sucrose (Suc) treatment to identify how Suc application affects sugar metabolism and induces senescence. Our results revealed that early decreases of Fv/Fm and increases in electrolyte leakage responded to Suc on day 3. Furthermore, a substantial increase in lipid peroxidation and up-regulated expression of senescence marker genes (NtSAG12) (except 60 mM on day 3) responded sequentially by day 5. The glucose, G6P, and HXK contents were first induced by Suc on day 3 and then repressed from day 5 to day 7. However, exogenous Suc treatment significantly improved the TPS content and the subsequent precursor T6P from day 3 to day 7. Following exogenous Suc treatments, the transcript level of NtSnRK1 was markedly down-regulated from day 3 to day 7. On the other hand, a linear regression analysis demonstrated that the T6P-NtSnRK1 signaling pathway was strongly associated with senescence initiation, and was accompanied by membrane degradation and NtCP1/NtSAG12 up-regulation by day 3. The T6P-NtSnRK1 signaling pathway experienced membrane and chloroplast degradation by day 5. HXK functioned as a metabolic enzyme promoting Glc-G6P and as a Glc sensor, accelerating the initiation of senescence through the HXK-dependent pathway by repressing PSII by day 3 and the senescence process through the Glycolytic pathway by day 7. These physiological, biochemical, and molecular analyses demonstrate that exogenous Suc regulates T6P accumulation, inducing senescence through the NtSnRK signaling pathway. These results illustrate the role of Suc and the transition of the sugar signaling pathway during the progression of senescence initiation.

为探究烟草株型特征和光合功能适应密植的机制,以中烟100为材料,设置HD(17857株/hm2)、MD(14286株/hm2)、LD(11905株/hm2)3个密度处理,探究种植密度对平顶期烟草第4叶位(L4)、第10叶位(L10)、第16叶位(L16)的光分布、株型特征、光合功能及叶片含氮量的影响.结果表明,密植降低了上部叶的大小和弯曲程度,增加了节长,提高了L4叶位的透光率,大幅降低了L16叶位的透光率;L4叶位的净光合速率和气孔导度均增加,比叶氮也显著增加,而叶绿素含量和比叶重无显著变化.L16叶位的净光合速率和气孔导度在高密度下显著降低,Fv/Fm、Y(Ⅱ)、qP和叶绿素含量也显著降低.密植导致L16叶位行间叶面积指数显著增加,而L4和L10叶位的株间和行间叶面积指数均无明显变化.增加种植密度还使冠层下部分布在行间的叶数增多.由此可见,烟草通过调节冠层叶片姿态改善光环境,适应密植环境,不同位置叶片光合功能对密植适应机制不同,上部叶通过提高光合能力适应高光环境,下部叶通过降低光合速率、加速衰老适应弱光环境,这有利于减少下部叶生物量,促进中上部叶发育,增加中上部叶比例,提高烟叶品质.

研究烟草主茎节距和茎围的生长动态及二者生长关系可为烟草合理株型塑造提供科学依据.以中烟100为试验材料,获取了团棵期到现蕾期烟株主茎节距和茎围的生长数据,通过Richards方程模拟不同部位节距、茎围的生长动态,采用标准化主轴回归估计方法分析节距和茎围之间的异速生长关系.结果表明:(1)所有部位主茎节距与茎围的Richards生长动态模拟均符合"S"型生长曲线(R2>0.9),其中中部茎节距的Richards生长动态模拟模型为典型的"S"型曲线,且RMSE检验表明精度、准确度高;(2)不同部位主茎节距最大值大小顺序为上部>中部>下部,不同部位主茎茎围最大值大小顺序为下部>中部>上部;(3)标准化主轴回归估计表明不同部位主茎节距和茎围之间、不同时期主茎节距和茎围之间都呈极显著的异速生长关系(p<0.001),异速生长斜率上部>中部>下部,团棵期>旺长期>现蕾期.以上结果表明,Richards方程与标准化主轴回归估计可以准确模拟烟草主茎生长动态及生长关系,烟草主茎先以节距伸长为主,后以茎围增加为主,烟草主茎伸长的关键时期是团棵与旺长期,主茎加粗的关键时期是现蕾期.本研究结果将有利于建立合理株型,提高烟株抗倒伏性.

Sucrose (Suc) accumulation is one of the key indicators of leaf senescence onset, but little is known about its regulatory role. Here, we found that application of high (120–150 mM) and low levels (60 mM) of Suc to young leaf (YL) and fully expanded leaf (FEL) discs, respectively, decreased chlorophyll content and maximum photosynthetic efficiency. Electrolyte leakage and malondialdehyde levels increased at high Suc concentrations (90–120 mM in YL and 60 and 150 mM in FEL discs). In FEL discs, the senescence-associated gene NtSAG12 showed a gradual increase in expression with increased Suc application; in contrast, in YL discs, NtSAG12 was upregulated with low Suc treatment (60 mM) but downregulated at higher levels of Suc. In YL discs, trehalose-6-phosphate (T6P) accumulated at a low half-maximal effective concentration (EC50) of Suc (1.765 mM). However, T6P levels declined as trehalose 6 phosphate synthase (TPS) content decreased, resulting in the maximum velocity of sucrose non-fermenting-1-related protein kinase (SnRK) and hexokinase (HXK) occurring at higher level of Suc. We therefore speculated that senescence was induced by hexose accumulation. In FEL discs, the EC50 of T6P occurred at a low concentration of Suc (0.9488 mM); T6P levels progressively increased with higher TPS content, which inhibited SnRK activity with a dissociation constant (Kd) of 0.001475 U/g. This confirmed that the T6P–SnRK complex induced senescence in detached FEL discs.

To develop an efficient method for quantifying tobacco plant types in the field, the three-dimensional (3D) point clouds of individual plant of five tobacco cultivars were reconstructed based on multi-view image sequences using the structure from motion method. According to the plant type characteristic indexes commonly used, ten phenotypic parameters such as plant height, top width, bottom width, and maximum width of leaf layer were automatically extracted based on the 3D point cloud of tobacco plant, and the calculation accuracy was evaluated based on the plant height and maximum width of leaf layer measured manually in situ in the field. The results indicated the coefficients of determination (R2) of the plant height and maximum width of leaf layer extracted from the 3D point cloud were all greater than 0.97, and the root mean square errors were 3.0, 3.1 cm, respectively. Meanwhile, the extracted phenotypic parameters of tobacco plants were analyzed by different methods. The results of intergroup correlation analysis showed that 16 pairs of traits were extremely significant positive correlations, while one pair of traits was extremely significant negative correlation. The results of one-way multivariate analysis of variance showed that there were highly significant differences among the plant types. The first three principal components were extracted by principal component analysis, and their cumulative contribution rate to the overall variance was 81.6%. The accuracy of plant type discrimination was 93.7% using Stacking ensemble learning method, which was significantly higher than those using random forest, support vector machine and naive Bayesian. This study can provide a method basis for phenotypic characteristics and plant type recognition of field-grown tobacco plants.

为了分析山东烟叶杂气及其类型与化学成分的相关性,解析杂气形成的化学基础,采集6个主要植烟区的中部烟叶(C3 F等级),进行感官质量评价和化学检测.结果表明,山东烟叶化学成分总体协调,杂气总体稍有,杂气类型以稍明显的木质气和枯焦气为主,常稍有生青气和土腥气,偶有些微青杂气、金属气和其它杂气.经简单相关分析发现,杂气总体或各类型与还原糖、总糖、淀粉、总氮、烟碱、钾、钠、硫、氯、纤维素和半纤维素其中一个或多个指标显著相关;而典型相关分析表明,杂气、刺激性与还原糖、硫、半纤维素、钠、氯等指标关系密切,杂气类型与氯、总糖、烟碱、半纤维素、纤维素等指标关系密切.所以,影响山东烟叶杂气的主要化学成分为氯、还原糖、总糖、硫、烟碱、半纤维素和钾,今后可采取相关措施进行调控,以提升产区烟叶质量.

为明确施氮量、种植密度及其交互作用对烤烟株型及产质量的调控效应,以'中烟100'品种为试验材料,采用二因素裂区设计,研究施氮量与种植密度对平顶期烟株干物质积累、株型性状、光合效率及烤后烟产量、产值、化学成分的影响.结果表明,随着种植密度的增加,烤烟群体叶面积指数增加,单产显著增加,高密度处理的最大叶叶位下降,单株干物质积累减少.随着施氮量的增加,烟株茎秆增高变粗,叶长、叶宽及叶绿素含量增加,上、中、下部叶干物质积累量提高,烤后烟叶烟碱、总氮含量增加,还原糖、总糖含量降低,化学成分可用性指数(CCUI)先增加后降低.方差分析可知,种植密度对平顶期烟株生物量积累的影响大于施氮量,对烤后烟品质的影响小于施氮量,且施氮量与种植密度的交互作用对产量、产值有显著影响.本研究以施氮量120 kg/hm2、种植密度27750株/hm2处理最佳,上、中、下部叶片CCUI值均大于85分,产量、产值分别达到2388.67 kg/hm2、38442.67元/hm2.表明在密植条件下,适当增加施氮量是弥补单株生产力不足及品质下降的有效措施.综合考虑产量、品质和效益,山东烟区'中烟100'以施氮量120 kg/hm2、种植密度18500株/hm2处理组合为最优,可实现烤烟的优质高效生产.

为探究温度影响烟草叶片细胞壁建成的机理和烟叶品质的机制,连续2年设置不同温度(15℃、20℃、25℃、30℃)处理的盆栽试验,研究不同温度对烟草叶片细胞壁物质含量和组成及合成酶基因表达量的影响.结果表明,含碳化合物在烟草叶片生长过程中及温度处理过程中发生了重新分配,随着烟草生长时间的延长,叶片中结构性碳水化合物(纤维素、半纤维素、木质素、果胶)含量整体表现为下降趋势,而非结构性碳水化合物(总糖、淀粉)含量大致表现为上升趋势;随温度升高,烟草叶片60 d时纤维素含量明显升高,而木质素含量及其占细胞壁总物质含量的比例明显降低;温度对半纤维素含量、果胶含量影响不显著.温度对纤维素含量、木质素含量的影响与其合成酶基因表达量的变化有关,温度升高有利于纤维素合成酶基因CESA1的上调表达,温度降低有利于木质素合成酶基因PAL1、4CL2的上调表达;温度变化对半纤维素合成酶、果胶合成酶基因表达的影响较小.

为明确山东中部烟区烤烟适宜移栽时间与移栽方式,采用田间对比试验,研究3个不同移栽时间(4月30日、5月10日和5月20日)及3种不同移栽方式(常规覆膜移栽、小苗膜下移栽和井窖式移栽)对烟株生长发育及烟叶产量和品质的影响.结果表明,随移栽期推迟,烤烟生育前期时间缩短,生育进程加快,烟株和叶片变大,烤后烟叶等级结构提升,化学协调性提高,经济产量和感官评吸质量先增加后微降;不同移栽方式在不同移栽期下对烤烟影响不同,早栽时,小苗膜下移栽和井窖式移栽可改善根系土壤温湿度环境,促进烟苗早生快发,提高烟叶评吸质量,但晚栽时,小苗膜下移栽由于地温过高对烟苗生长产生负面影响,进而影响烟叶产量和品质.移栽期主要通过生育期内温度条件的变化对烟株产生影响,为主要影响因素;移栽方式通过改变生长前期微环境对烟株生长起到微调作用.以5月10日的井窖式移栽处理综合表现最好,可作为鲁中烟区适宜的移栽时间和方式进行示范应用.