Plant Chemical Defenses against Insect Herbivores—Using theWild Tobacco as a Model

The Nicotiana genus, commonly known as tobacco, holds significant importance as a crucial economic crop. Confrontedwith an abundance of herbivorous insects that pose a substantial threat to yield, tobacco has developed adiverse and sophisticated array of mechanisms, establishing itself as a model of plant ecological defense. Thisreview provides a concise overview of the current understanding of tobacco’s defense strategies against herbivores.Direct defenses, exemplified by its well-known tactic of secreting the alkaloid nicotine, serve as a potent toxinagainst a broad spectrum of herbivorous pests. Moreover, in response to herbivore attacks, tobacco enhancesthe discharge of volatile compounds, harnessing an indirect strategy that attracts the predators of the herbivores.The delicate balance between defense and growth leads to the initiation of most defense strategies only after aherbivore attack. Among plant hormones, notably jasmonic acid (JA), play central roles in coordinating thesedefense processes. JA signaling interacts with other plant hormone signaling pathways to facilitate the extensivetranscriptional and metabolic adjustments in plants following herbivore assault. By shedding light on these ecologicaldefense strategies, this review emphasizes not only tobacco’s remarkable adaptability in its natural habitatbut also offers insights beneficial for enhancing the resilience of current crops.

Climatic Characteristics of Hubei Tobacco Area and Its Influence on the Quality of Upper Leaves

In order to provide a more suitable environment for tobacco leaf growth, this study collected meteorological information and tobacco leaf quality information from the main tobacco-producing counties in the province and conducted relevant analysis to find out the main meteorological factors affecting the growth, development, yield, and quality of upper tobacco leaves. Clarify the suitable climatic conditions for the growth and development of the upper leaves, and clarify the influence of various meteorological factors on the quality of the upper leaves. The results showed that the nicotine and total nitrogen content of the upper leaves were significantly positively correlated with the average daily temperature during the maturity period, and negatively correlated with the rainfall during the maturity period;the rainfall in July was significantly positively correlated with the upper leaf clutter score, which was sufficient in the mature period. Moisture conditions are conducive to alleviating the upper leaf clutter;the number of sunshine hours in August is the main factor affecting the content of aroma substances in the upper leaves, and it is also significantly positively correlated with the content of aroma substances.

Homogeneous Synthesis and Characterization of Quaternized Cellulose Derivatives in NaOH-urea Aqueous Solutions

Quaternized cellulose( QC) derivatives were synthesized by reacting cellulose with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride( CHPTAC) in an aqueous solution of Na OH-urea. The chemical structures and physical properties of the obtained QC derivatives were characterized using nitrogen content analysis,Fourier transform infrared spectroscopy( FT-IR),~1H-nuclear magnetic resonance(1H-NMR),X-ray diffraction( XRD),and thermal gravity analysis( TGA). The FT-IR and ~1H-NMR results confirmed the successful introduction of cationic quaternary ammonium groups into the main chain of cellulose. A series of QC derivatives with the degree of substitution( DS) values ranging from 0. 33 to 0. 80 were derived by adjusting the molar ratio of CHPTAC to anhydroglucose unit( AGU) of cellulose,concentration of cellulose in the Na OH-urea solution,as well as reaction temperature and time. According to the DS values of the QC derivatives,the optimized synthetic conditions were as follows: 25℃ reaction temperature,3% cellulose in Na OH-urea solution,the molar ratio of etherification agent to glycosidic cellulose of 15∶ 1,and 12 h reaction time. The TGA and XRD results revealed that the crystalline structure was destroyed during etherification,and the thermal stability of the QC derivatives was lower than that of cellulose.

Adsorption characteristics of surfactants on secondary wood fiber surface

Surfactant residues in recycled wood fiber from the deinking process can have impact on the subsequent bleaching and papermaking processes by increasing bleaching agents and disturbing papermaking wet-end chemistry.In this paper,the fundamental mechanism of surfactants adsorption characteristics on secondary fiber surface was studied.The adsorption isotherms and kinetics of an anionic surfactant,sodium dodecyl benzene sulfonate(SDBS)and a non-ionic surfactant,Triton X-100(TX-100)on secondary fiber surface with or without the presence of electrolytes(Mg^(2+)ions)were studied by using spectrophotometric methods.Results showed that the adsorption isotherm of SDBS could be subdivided into four regions,and the adsorption of SDBS was increased with the presence of Mg^(2+)ions.While for TX-100,the adsorption isotherm showed typically Langmuir-type adsorption,and its adsorption was decreased with the presence of Mg^(2+)ions.Kinetic analysis indicated that the adsorption processes both fit pseudo-second-order model well.The adsorption rate of both surfactants was affected by the initial surfactant concentration,electrolyte and temperature.The activation parameters confirmed that the adsorption processes of both surfactants were typically diffusion-controlled and endothermic at a temperature range commonly used for current flotation deinking processes.SDBS and TX-100 mainly adsorbed to the hydrophobic sites of secondary fibers surface,which decreased the fiber hydrophobicity and reduced the fiber loss in the flotation deinking process.The results suggested that the concentration of Mg^(2+)ions should be maintained at a low level when SDBS was used in the flotation process.