The influence of stands cultivation on persistency of different cultivars of Medicago sativa L

A polyfactorial field trial with alfalfa (Medicago sativa L.) cv. Palava, Jarka and Vlasta was established in Červený Újezd (altitude405 m a.s.l., average year precipitation493 mm per year, average year temperature 7.6°C, clay loam orthic luvisol) in the spring with a companion crop (spring wheat) in rows of a space of125 mm, sowing rate 16 kg/ha of germinable seeds in the year 1998. The stands were cut 3 times per year, the control variant was left without a treatment, the rest were cultivated with a spike or a vibration harrow before the beginning of the vegetation season and after the first cut. The numbers of plants and stems per m2 and dry mass yields were measured. The results were evaluated by four-factor analysis of variance Anova and by regression analysis. The harrowing of the stands resulted in a significantly lower amount of plants per m2 in the end of the fourth year by 23-29%, on average a lower number of stems per m2 (by 13% using double cultivation per year with the vibration harrow). The dry mass yield was significantly influenced only with cv. Jarka (by 5-11% higher in the cultivated fields). The moderately or relatively strong relationship between the plants amount and the time was exponential.