Background. At present, sufficient attention is paid to the analysis of the effect of natural and synthetic growth regulators and their influence on the induction processes of plant morphogenesis. The issues of studying the growth processes taking into account the external regulation of this process at the level of the whole plant organism with the fixation of changes in the linear and volumetric indicators of its organs are relevant. The purpose of the research was to study the effect of natural and synthetic growth regulators on the growth and metabolic processes of grain crops at the early stages of plant development.
Materials and methods. The objects of study were: spring wheat of the Tulaykovskaya 10, barley of the Nutans 642, and the Allur oats. Presowing seed treatment was carried out with growth regulators: melafen (1 · 10–7 %), pyrafen (1 · 10–7 %), pectin (5 · 10–2 %), crezacin (1 · 10–3 ml/l), ribav-Extra (1 · 10–4 ml/l), zircon (4 · 10–3 ml/l). The studies were carried out in small-plot field experiments, where the dynamics of the formation of the root system in terms of the volume of the root system, the dynamics of growth of the leaf surface, the content of NPK and the wet weight of plants at the early stages of growth and development were determined.
Results. Cereals are characterized by active growth of the root system during the juvenile period. In studies carried out on oats, it was shown that, regardless of weather conditions, an increase in the volume of the root system occurred until the stage of milky ripeness. The maximum rate of growth processes under the influence of pectin and melafen was noted at the first stages of plant development. The excess over the control in the tillering and tubing phases was 21,4–37,5 and 17,8–45,5 %, respectively (P < 0,05). The greatest increase in the volume of the root system of spring wheat plants under the influence of melafen and ribava-Extra was noted in the tillering phase and amounted to 12,8 and 21,3 %, respectively (P < 0,05). In experiments on barley, a significant effect was observed in the variant with melafen. The formation of the root system proceeded more intensively than in the control by 33,9 % in the tillering phase and by 38,4 % in the tubing phase (P < 0,05). In studies on oats, it was shown that in the control variant, the nitrogen content in the green mass of plants during the entire growing season was at a low level. At the same time, the content of phosphorus and potassium was optimal. Treatment with growth regulators led to an increase in the nitrogen content in oat plants by 1,12 and 1,09 times (melafen and pectin, respectively). Barley plants in the control variant without additional fertilization at the early stages of growth contained 3,20 % nitrogen in terms of absolutely dry matter, which characterizes the lack of this element. The use of growth regulators led to an increase in nitrogen content by 1,09–1,12 times (tillering) and by 1,13–1,18 times (going into the tube). The leaf surface area of oats in the tillering phase increased under the influence of pectin and melafen by 4,8–14,8 %. In the phase of entering the tube – by 21,6–31,1 %. On spring wheat, Melafen and Ribav-Extra had the greatest influence. In the tillering phase, the increase was 19,3 and 26,8 %, respectively, in the stemming phase – 22,4 and 32,7 %. On barley, it was noted that in the juvenile period under the influence of growth regulators,
the excess of the control indicators was 18,8–23,7 %. The parameters of leaf plates (leaf length) changed without changing the number of leaves on the plant. The wet weight of the plants changed in accordance with changes in the growth of the root system and leaf surface. However, the excess of the control values in terms of the wet weight of plants was slightly lower than the total effect of stimulating root growth and indicators of the volume of the root system and leaf surface of the studied plants.
Conclusions. It was determined that endogenous regulation promotes the activation of the growth and metabolic processes of the vegetative organs of plants at the juvenile stage of morphogenesis. The highest growth rate is observed in the age periods corresponding to the tillering and stemming phases in all studied crops.
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