- Journal Details
- Format
- Journal
- eISSN
- 2719-9509
- First Published
- 01 Jan 1992
- Publication timeframe
- 4 times per year
- Languages
- English
Search
- Open Access
Nicotiana: Breeding Research and Breeding - Nicotiana: Züchtungsforschung und Züchtung
Page range: 103 - 137
Abstract
Starting from the description of the structure, number and meiotic behaviour of chromosomes, the evolution of the economically important Nicotiana species is analysed. Flowering, expected fertility, incompatibility and male sterility, seed development, as well as germination, are used as criteria to outline the principles of Nicotiana breeding. The chapter entitled “Sortenzuechtung” (variety breeding) includes a survey of the development of varieties, the breeding material available and that to be established. The application of sterile culture techniques in Nicotiana breeding is discussed. The presentation of the different breeding methods applied includes compilations of released tobacco varieties.
- Open Access
Fluctuations in Protein Levels of Tobacco Leaves and Consequences for Extractability
Page range: 139 - 149
Abstract
Greenhouse and field experiments were conducted to evaluate the effect of time, cultural conditions and genetic factors on protein extractability from tobacco leaves. Leaf protein was periodically extracted from green tobacco from time of transplanting through early senescence. Intensive sampling revealed substantial fluctuations in protein concentrations superimposed upon an age-related decline in protein levels with approaching plant maturity. Predictably, these oscillations affected the degree of protein extractability. Combined totals of the three major soluble protein fractions, viz. the green chlorophyll/protein complex, the white Fraction I protein (cryoprecipitate), and the white Fraction II protein (thermoprecipitate), deviated occasionally from protein values in unfractionated homogenates, but the fluctuation trends were similar. Investigations of variations in protein extractability among greenhouse-grown tobacco and selected genotypes grown under field conditions revealed that protein fluctuations during plant development are a common phenomenon. It is concluded that the occurrence of periodic fluctuations in total protein concentration and in the amount of extractable protein can severely distort estimates of leaf protein yields that are based upon insufficient numbers of samples and prolonged intervals between sampling.
- Open Access
An Automated Procedure for the Determination of Total Alkaloids in Cigarette Smoke Using On-line Cyanogen Chloride Generation from Low Hazard Starting Materials
Page range: 151 - 155
Abstract
An automated procedure is described for the determination of alkaloids in cigarette smoke using low toxicity reagents. Cyanogen chloride is formed on line from potassium thiocyanate and sodium hypochlorite. The procedure is compared with the previously used cyanogen bromide method which also uses Auto Analyser II methodology.