Formation of agrobiological parameters of sorghum bicolor plants (Sorghum bicolor L.) depending on the density of the agrocenosis of the crop in the Right-Bank Forest-Steppe of Ukraine

Abstract

The goal is to investigate the process of formation of agrobiological parameters of sorghum bicolor plants (Sorghum bicolor L.) by foreign hybrids and domestic varieties depending on the density of the agrophytocenosis and the use of a growth biostimulant. Methods. Laboratory, measuring, calculation-comparative, analysis, statistical. Results. The duration of the growing season depended on the density of the agrocenosis. With an increase in the density of the stem from 160 to 200 thousand pcs./ha, a slight (by 1-2 days) lengthening of the growing season is noted. When using the growth regulator "Appetizer" (0.5 l/ha) in the tillering phase (4-5 leaves) at a density of 160-180 thousand pcs./ha, the duration of the growing season in all genotypes compared to the control did not change, since the plants have a sufficient area for nutrition and low competition for light and moisture. At a density of 200 thousand pcs./ha, the effect of the drug "Appetizer" mitigated the stress associated with increased competition of plants for vital factors, which reduces the negative impact of density on the duration of the growing season. It was established that the formation of the leaf apparatus significantly depends on both the density of the plant stand and the use of the growth regulator "Appetizer", which partially compensates for the potential stress from increased competition for resources in denser agrocenoses of the crop. The effectiveness of the stimulant was clearly manifested in the panicle ejection – flowering phases. The area of sorghum leaves in the tube phase increased almost 2 times at plant densities from 160 to 200 thousand pcs./ha, and with the introduction of a growth regulator at all studied densities, the leaf surface area increased by an average of 2%. In the tube phase – panicle ejection, the highest value (226.1-350.3 cm2) of the area was observed at a density of 200 thousand pcs./ha. In the flowering phase, at plant densities of 160–200 thousand pcs./ha, the development of the leaf apparatus was maximum (358.5-368.2 cm2). In the organogenesis phase, the full ripeness of the grain, the difference between the studied densities was leveled, since the leaves are already partially dying off. The use of the growth stimulator "Appetizer" stably increases the leaf surface area at all phases of development. The increase is on average 2–5% in the early phases and 3–8% in the flowering phase. The strongest effect of the regulator is in the panicle-flowering phase. Conclusions. The combination of optimal plant density (180 thousand pcs./ha) and the use of a growth stimulator is an effective agrotechnological method of increasing the photosynthetic activity of sorghum hybrids, which creates the prerequisites for the formation of higher productivity and better realization of the genetic potential of common sorghum.