Root system size of alfalfa varieties under different plant densities

The field experiment was established from pre-grown alfalfa sprouts in 2008. In 2009 and 2010, the harvest was carried out. The yield and the root size system (RSS) were evaluated in the total of five cuts. Two localities of diverse soil and weather conditions were selected. Žabčice is a dry location with a highly permeable sandy soil layer, but at the same time, with a considerable fluctuation of the underground water level; Troubsko, on the other hand, represented a location with a higher content of clay in soil suitable for growing alfalfa. The trial was established in two types of plant spacing – 25 × 25 cm (16 plants per m2) and 50 × 50 cm (4 plants per m2). Two alfalfa varieties were used – Hodonínka (an old variety) and Oslava (a new variety). The following factors were evaluated by statistical means: location, variety, plant spacing, and cut number. The effect of location on the above ground phytomass and the RSS value proved highly statistically decisive. The higher average values of above ground phytomass as well as RSS were achieved on the Troubsko location where the above ground phytomass was 19.57 t.ha−1 and RSS was 2.71 nanofarad (nF). The impact of the variety was highly statistically significant only in respect to RSS. The effect of variety on the alfalfa above ground phytomass was not proven. The higher average RSS values were reached by the Hodonínka variety (2.59 nF). The effect of the plant spacing on both the above ground phytomass and the RSS values was highly statistically significant. The higher average above ground phytomass was achieved when the 25 × 25 cm plant spacing was employed (18.64 t.ha−1). As for the RSS value, the case was exactly opposite – the higher average value was reached when the plant spacing was 50 × 50 cm (2.99 nF). The impact of the cut number on both the above ground phytomass and the RSS was highly statistically significant. The highest average above ground phytomass and root system size were measured in the third cut. The above ground phytomass was 30.36 t.ha‑1 and RSS was 3.86 nF.