Search

The chemistry, aroma, solubilities (herane and 95% ethanol), and smoking quality of cured tobacco from three typical flue-cured varieties that produce glandular trichomes on the surface of the green leaf and an atypical aglandular breeding line were compared. The glandular tobaccos produced more characteristic tobacco aroma than the aglandular tobacco. More hexane-extractable solute was obtained from the aglandular tobacco than from the glandular flue-cured tobaccos, but more alcohol-extractable solute was obtained from the glandular types

Surface chemicals of green tobacco leaf were obtained by dipping the leaf into methylene chloride. Leaf wash procedures were developed and evaluated for both small and large numbers of samples. Cuticular constituents containing alcohol functions were derivatized with trimethylsilyl reagents and analyzed by glass capillary gas chromatography on SE-54 columns. Quantitative data were obtained for the major cuticular diterpenoids a- and fl-4,8,13-duvatriene-l-ols, a- and j3-4,8,13-duvatriene-l,3-diols, cis-abienol, labda-13-ene-8,15-diol, and docosanol, hydrocarbons, and sucrose esters. The application of this method allowed the characterization of the cuticular constituents of numerous tobacco varieties and introductions. The relationships between cuticular composition and insect resistance are presented and discussed. The green leaves of commercial tobacco varieties are covered with a gummy exudate, and the composition of these cuticular waxes may be of significant importance. Dietrich and Demole (1977) and Enzell (1977) have reported that the degradation of the cuticular diterpenoids of green tobacco, during curing and aging, results in the production of numerous volatile terpenes, which may be important tobacco flavor components. Reid (1975) reported that a diterpene fraction, isolated from green leaf cuticular waxes, contained precursors of aroma constituents of commercial tobacco. Cutler et al. (1977) have found that the cuticular diterpenes of green tobaccos have plant growth inhibiting properties. The levels of specific cuticular components are believed to be responsible for the observed resistances of some types of tobacco to green peach aphids [Myzus persicae (Sulzer)], tobacco budworm [Heliothis uirescens (F.)], and tobacco hornworm [Muduca sextu (L.)] (Johnson and Severson, 1982,1984; Severson

Cuticular components from the green leaves of a typical flue-cured tobacco, NC 2326, were removed and sprayed onto the leaves of a tobacco budworm-resistant entry, TI 1112. Both the whole leaf wash (WLW) from NC 2326 and the methanol-water soluble (MWS) fraction of the NC 2326 WLW stimulated budworm oviposition onto the previously nonpreferred TI 1112 in cage bioassays and field experiments. The hexane soluble (HS) fraction of NC 2326 WLW did not significantly increase tobacco budworm egg laying. The major components in the NC 2326 MWS fraction were the α- and β-4, 8, 13-duvatriene-1, 3-diols. Hydrocarbons, fatty alcohols, and wax esters were identified in the NC 2326 HS fraction.

Apport au sol et pulverisation des plantes avec du selenite de sodium. Comparaison de l'efficacite des 2 modes de traitements a accroitre la teneur en Se. Apres pyrolyse du tabac traite en carneaux on observe la teneur en Se de la fumee de cigarettes

Cuticular components of green tobacco, Nicotiana tabacum L., leaves affect insect–plant relationships associated with host-plant resistance. Formation and composition of these chemicals was investigated using intact and reciprocally grafted tobacco plants. Reciprocal grafts were made between scions and rootstocks of ‘NC 2326,’ flue-cured tobacco, and two insect-resistant tobacco introductions, TI 165, and TI 1112. Field resistance to green peach aphids, Myzus persicae (Sulzer), tobacco budworms, Heliothis virescens (F.), and tobacco hornworms, Manduca sexta (L.), was retained by TI 1112 and TI 165 scions regardless of rootstock. Tobacco budworm larval survival and weight gain was highest on all NC 2326 scions. Budworm moths laid few eggs on ungrafted TI 1112, on TI 1112 scions grafted on NC 2326, or on TI 1112 grafted on its own rootstock. Levels of cuticular chemical components were similar among like scions. Thus, rootstock type apparently does not affect production of cuticular components nor insect resistance in TI 1112 and TI 165.

The HLC deproteinized product [depro] with 34 % of its original dry weight removed as heat precipitable protein fractions, shows a reduction in the levels of most of the cured product constituents and the major pyrolyzate constituents while the levels of polycyclic aromatic hydrocarbons and volatile nitrosamines in the pyrolyzates from the HLC deproteinized product were increased. This indicates that the precursors of the polycyclic aromatic hydrocarbons in the pyrolyzate from the HLC deproteinized product were not removed with the protein precipitates. Another possibility is that some constituents in the protein precipitates that were removed from the HLC deproteinized product may have had an inhibitory effect toward the formation of the polycyclic aromatic hydrocarbons in the pyrolyzates of the HLC control and flue-cured reference during their pyrolysis, since the protein precipitates were not removed from these products. Generally, the levels of polycyclic aromatic hydrocarbons from the pyrolyzates of the HLC products were higher than those from the pyrolyzates of the flue-cured reference. This could be a result of the tobacco maturity or curing methods. The level of the volatile nitrosamines in the pyrolyzates of the HLC control was lower than those levels in the pyrolyzates of the HLC deproteinized and flue-cured reference products. This could be due to pyrolytic interaction between some constituents in the sample and the protein precipitate which was not removed from the HLC control product. Additional work is needed to clarify these differences. A reduction in the level of solanesol was evident in the HLC deproteinized product probably due to the association of solanesol with the chloroplastic protein precipitate that was removed from that product. In addition, the level of solanesol was highest in the flue-cured reference, which is in agreement with previous reports that solanesol concentration increases with tobacco maturity. This report demonstrates that HLC can be used to manipulate the chemical composition of tobacco. The levels of some major constituents were decreased while the levels of polycyclic aromatic hydrocarbons were increased in the pyrolyzate from the same tobacco product.

Condensate deliveries from cigarettes can be reduced by manufacturers in various ways. Lines or cultivars of tobacco can also be developed whose cured leaf, upon pyrolysis, delivers less condensate in the smoke. Since there appears to be an association between condensate and nicotine in smoke, the condensate : nicotine ratio is important to the development of lines of tobacco that deliver low condensate levels. Experiments were conducted to evaluate the potential for genetically controlling condensate delivery in cigarette smoke and data are presented. In general, when comparing the condensate delivery potential for different classes of tobacco, Burley delivered higher condensate values followed by dark fire-cured, dark air-cured, flue-cured and Maryland cultivars. In selecting genotypes for lowering condensate deliveries, the condensate / g of tobacco smoked is a better index than condensate/cigarette. In evaluating low-alkaloid tobaccos, the condensate delivery did not decrease appreciably as the total alkaloids were decreased. On an average, the decrease was about 4 mg of condensate / cigarette when compared with normal-alkaloid types but the condensate : nicotine ratio increased greatly. The ratio of condensate : nicotine was lowered when lines high in nicotine were produced. In one test reported, the ratio of condensate : nicotine ranged from 5.3 (TI 717) to 75.0 for a low-nicotine line. N. rustica had higher nicotine than N. tabacum cultivars and a lower condensate : nicotine ratio. The gene(s) responsible for the production of nicotine in N. rustica were transferred into N. tabacum and some of the derived lines had a nicotine content about 1 % higher than SC 58, the highest-nicotine cultivar, or flue-cured tobacco available. The condensate delivery / g of tobacco smoked was lower for these lines when compared with SC 58. All of the lines tested gave a condensate : nicotine ratio lower than SC 58. The data showed that condensate deliveries from tobaccos vary with the environment, cultural practices and the weather conditions under which the tobacco is produced. To make progress in breeding for lower condensate delivery in tobacco, it is necessary to assay large numbers of samples and methods for doing this were discussed. To breed low-condensate delivery lines with good smoking flavour, it will be necessary, simultaneously, to select for certain flavour compounds. More research is needed on flavour chemicals of tobacco and their relationship to condensate.