Synthesis, Characterization, and Encapsulation of Novel Plant Growth Regulators (PGRs) in Biopolymer Matrices

Novel plant growth regulators (PGRs) based on the derivatives of dehydroamino acids 2,3-dehydroaspartic acid dimethyl ester (PGR1), Z-isomer of the potassium salt of 2-amino-3-methoxycarbonylacrylic acid (PGR2) and 1-methyl-3-methylamino-maleimide (PGR3) have been synthesized and their growth-regulating properties investigated. Laboratory testing revealed their plant growth-regulating activity. PGR1 showing the most stimulating activity on all laboratory tested cultures were used in field experiments. Results showed that PGR1 is a highly effective environmentally friendly plant growth regulator with effects on different crops. Biopolymeric microcapsule formulations (chitosan/alginate microcapsule loaded with PGR) suitable for application in agriculture were prepared and characterized. Physicochemical properties and release profiles of PGRs from microcapsule formulations depend on the molecular interactions between microcapsule constituents including mainly electrostatic interactions and hydrogen bonds. The differences in the microcapsule formulations structure did not affect the mechanism of PGRs release which was identified as diffusion through microcapsules. The obtained results opened a perspective for the future use of microcapsule formulations as new promising agroformulations with a sustained and target release for plant growth regulation.

Screening of growth-simulating activity of synthetic compounds - pyrimidine derivatives

New synthetic compounds — pyrimidine derivatives — were screened to select the most effective of them, which show a growth-regulating activity in plants. Their action was compared with phytohormones of the auxin class. In particular, the effect of synthetic compounds on the seed germination, growth, and development of tomato (Solanum lycopersicum L.) plants of Lagidny variety in vivo and in vitro was studied. It was found that some of the studied compounds have a positive effect on the morphometric and biochemical parameters of 30-day-old plants: compounds D1-D5 increased seed germination up to 9-27 %, the most effective among them was compound D1. Compounds D1 and D2 increased the height of the shoots up to 29 %. All the studied compounds effectively influenced the rooting of plants, increasing either the length of the roots (up to 8 %) or their number (up to 25 %), the most effective among them was the compound D2. The effect of these compounds on the morphogenetic potential of tomato explants was studied in vitro for the first time. It was found that compounds D1 and D2 were the most effective for the direct plant regeneration. Screened compounds can be further recommended for the use in various biotechnological programs for genetic improvement of tomatoes.

Fluorescent and growth-regulating activity 2-phenylethenylphosphonic acid derivatives

The paper provides data on an improved method for the synthesis of 2-phenylethenylphosphonic acid dichloride by interacting of carbamide derivatives with 2-phenylethenyltrichlorophosphonium hexachloro-phosphate, which is an intermediate adduct of the reaction of styrene and phosphorus pentachloride. Readily available urea, biuret, and acetylurea have been used as transformers of the adduct. It has been shown that carbamide derivatives are not only donors of the oxygen atom, but they also bind hydrogen chloride released at the stage of complexation into the corresponding hydrochlorides. This allows obtaining the target 2-phenyl-ethenyldichlorophosphonate without admixture of the hydrochlorination by-product. The phenomenon of induced fluorescence of 2-phenylethenylphosphonic acid and its esters in the solid phase and in solution was revealed. The growth-regulating activity of 2-phenylethenylphosphonic acid and O,O-di(p-nitrophenyl)-2-phenylethenyl-phosphonate on the seed germination energy, laboratory and field germinations of grain and vegetable crops was established. It is shown that pre-sowing treatment of the Prokhorovka spring wheat seeds with a 0.0005% aqueous solution of O,O-di(p-nitrophenyl)-2-phenylethenylphosphonate leads to an increase in wheat yield by 21%, which expands the range of products for this purpose. A study of the acute toxicity of 2-phenylethenylphosphonic acid according to LeBlanc on male rats kept on a standard vivarium diet showed that it has a two-phase effect. In the first phase, there are symptoms of damage to the motor part of the peripheral nervous system in the form of local seizures and the central nervous system in the form of the general suppression of motor activity and moderate relaxation of skeletal muscles, and in the second phase, the acid manifests itself in a general toxic effect. Determination of the LD50 of 2-phenylethenylphosphonic acid showed that it belongs to the third class of toxicity – low-hazard substances.

The effectiveness of 2-alkilthionicotinenitrilles derivatives as growth regulators on winter wheat

Some derivatives of 2-alkilthionicotinenitrilles were synthesized for the search of the new winter wheat growth regulators. The growth regulating activity of the new compounds was studied and the substances with high growth-stimulating effect were found.

Study of the growth-regulating activity of pyrazolopyridine derivatives on soybean plants

The aim of this work was to find new active substances to create domestic soybean growth regulators. The screening was carried out in a series of naphthalene-2-sulfonyl amide derivatives. Substances with high growth-stimulating activity were identified.