We studied the effect of benzylamine, benzyl alcohol, and their derivatives (constituting a new group of synthetic analogues of natural auxins) on rooting of leaf and stem cuttings, rhizogenesis and growth of barley plantlets and tomato seedlings, and tomato plant productivity. These compounds promoted rooting of leaf and stem bean cuttings, increased rhizogenic activity, and stimulated the development of root systems in barley and tomato seeds. The activity of the compounds studied was similar to that of standard substances (3-indoleacetic acid potassium salt and 2-naphthylacetic acid). The benzyl group attached to the oxygen or nitrogen atom was shown to be the smallest molecular structure which provided auxin activity of the compounds. Derivatives of benzyl alcohol containing the quaternary ammonium fragment possessed auxin and antigibberellin (retardant) properties. They were selected by chemical synthesis of low-molecular-weight bioregulators with desired properties (a combination of chemical fragments with complementary physiological activity in the molecule). Auxin and anti-gibberellin (retardant) activities produced a synergistic effect. Germination of seeds treated with these compounds was accompanied by a more significant increase in the weight and length of roots (compared to standard auxins). The rate of seedling establishment reached 100%. The development of fruits and accumulation of reserve nutrient substances were synchronized and accelerated after spraying vegetating plants with solutions of studied compounds. The synergistic effect underlay a significant increase in the amount and quality of the crop (e.g., tomatoes).

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The importance of six theoretically calculated molecular parameters in the antigibberellin (retardant) activity of quaternary ammonium salts is studied using regression analysis. A bioassay system based on cell culture of fungus Gibberella fujikuroi is used to determine the activity. In the case of N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium chloride (choline) and N,N,N-triethyl-N-(2-hydroxyethyl)ammonium chloride (N,N,N-triethylcholine) derivatives with linear structure, the polarizability, proton acceptor activity, and lipophilicity of these compounds exert the largest effect on the antigibberellin activity. The antigibberellin activity of more sterically hindered N,N-dialkylpiperidinium salts was mainly defined by the steric parameter, while the polarizability, proton acceptor activity, and (through them) lipophilicity exert a lesser effect. Other parameters are of minor importance for the three groups of compounds studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.

Reaction of the trimethylsilylphosphorimidic triamide (I) with xenon difluoride (II) gives the N'''‐fluoro compound (III).

Phytohormonal regulation of the growth and development of plants is chosen as a physiological model for developing the strategy of chemical design of effective phytoregulators and stress protectors. The strategy [1 − 3] is based on the following assumptions.(1) Several, rather than one, life-supporting systems participate in the formation of the response of living organisms to any external influence. Even weak but simultaneous stimulating influence on some systems, forming a given character can cause a strong responding effect.(2) It is necessary that these influences should be complementary and coordinated.(3) The physiological activity of a molecule is a result of the interaction of its effector chemical fragments with the receptors of those systems which form the given character (quality).(4) Physical and chemical properties of the effector fragments and the whole molecule (their topochemistry and molecular parameters, including the affinity for proton, water and lipids) do not determine the regulation influence qualitatively. Instead, they strengthen or weaken it quantitatively to the degree corresponding to the structural requirements of structure the receptors of regulatory systems.Auxins and gibberellins, as natural phytohormones, carry out complementary functions in two key processes in the life of a plant: (a) the germination of a seed and rooting of the sprout and (b) the formation and development of fruits and seeds [4,5]. During germination, auxins provide rhizogenesis and gibberellins, the growth of the above-ground part of a plant. Additional stimulation of sprout rooting by auxins accompanied by a slight inhibition of the development of the aboveground part would allow redistributing stocks of nutrients of a seed for the benefit of rhizogenesis, which, in turn, would increase the stability and efficiency of crops. The same auxins together with abscisins control the flow of plastic substances from the feeding flag leaf to the developing seeds and fruits during fructification. Shortage of auxin largely determines the heterogeneity of maturing fruit ripening and slows down their development. During fructification, the inhibition of an excessive growth of the above-ground part of a plant is useful for crop, because it allows redistributing mineral and water for fruit development. Hence, phytoregulators to be designed should have two complementary growth-regulation activities: auxin and antigibberellin (retardant).On the basis of the developed strategy, compounds I, II and III [6] were selected (Table 1). They combine chemical fragments with auxin (the O-benzyl fragment) and with retardant (the quaternary ammonium group) activities favors fast and effective rooting of sprouts developing from seeds subjected to preceding processing. This raises the efficiency of a plant and its stability to stresses and phytopathogens, whereas the radionuclide carry-over from the ground is decreased [7,8]. During the preharvest processing of a plant with solutions of salts I, II and III, developing fruits receive additio...