Effect of weather, nitrogen fertilizer, and biostimulators on the root size and yield components of Hordeum vulgare

In this study, the effect of nitrogen doses (52, 80, 110, 140 kg/ha N) and the application of biostimulant preparations containing Ascophyllum nodosum L. algae extract were assessed. During the years 2018–2019, the influence of the preparations on the electrical capacity of the roots (C R) and yield components of spring barley was determined. Root electrical capacitance was determined in growth stages 45–50, 55–65, and 70–75 according to the BBCH-scale. The best phases of vegetation growth for the application of biostimulators with Ascophyllum nodosum extract were the barley tillering and elongation phases. This application increased C R while reducing the amount of N required to achieve similar or higher production of barley yield components compared to high N treatments. The root electrical capacitance, the number of productive tillers, and the number of grains per plant were significantly influenced (p > 0.05) by the weather of the year. The number of productive tillers was closely correlated with C R (r = 0.912**) as well as the number of grains per plant (r = 0.859**) and their weight (r = 0.850**). These relationships were the highest at the beginning of the grain formation (BBCH 70–75). Foliar biostimulation was not very effective in the dry year of 2018. The problem may be the foliar application itself. The effect of foliar application is strongly dependent on weather conditions and may be ineffective in many cases. We recommend the foliar application of effective biostimulants in tillering and elongation phases. They can reduce production costs and environmental pollution by reducing the amount of fertilizer needed while maintaining yields.