Physical chemical studies of short-chain lecithin homologues. II. Micellar weights of dihexanoyl- and diheptanoyllecithin

The micellar weights of dihexanoyl- and diheptanoyllecithin in aqueous solutions are calculated from light scattering and ultracentrifugation data. A monomer-micelle assocation model is used and corrections for the thermodynamic nonideality, on the basis of rigid noninteracting particles, are applied. A few experiments on the influence of high NaCI concentrations (up to 3 M) are described. Dihexanoyllecithin forms micelles with micellar weight of 15 000 to 20 000 and with rather narrow weight distributions. Diheptanoyllecithin micelles however, have broad size distributions with micellar weights of 20 000 up to about 100 000 in the concentration range studied. Micelles are assumed to be spherical or to have sphero-cylindrical shapes depending on the molecular weights. Two models are used: (1) a compact structure, where no attention is paid to the hydrocarbon-water contact (2) micelles with as little hydrocarbon-water contact as possible.     

Plant resistance to Myzus persicae induced by a plant regulator and measured by aphid relative growth rate

Myzus persicae showed a reduced relative growth rate on plants given soil drenches of 1% CCC (a plant growth retardant), and a greater reduction when CCC was applied as a foliar spray. The use of the relative growth rate of aphids as a convenient measure of their performance in relation to plant resistance is discussed.

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Zusammenfassung Die Resistenz von Kohlpflanzen, die mit 1% CCC (einem Regulator des Pflanzenwachstums) behandelt worden waren, gegen Myzus persicae wurde mit Hilfe des Wachstumsquotienten der Blattläuse (g/g/Tag) gemessen. Diese Methode arbeitet rasch und ergibt eine ziemlich geringe Variabilität. Der Maßstab scheint sinnvoll und ziemlich empfindlich zu sein.Mit CCC gedüngte Pflanzen zeigten stets eine ziemlich starke Verminderung des Wachstumsquotienten von Myzus persicae. Wurde CCC auf die Pflanzen aufgesprüht, so ergab sich ein noch geringerer Wachstumsquotient der Blattläuse.