PRODUCTION ABILITY AND PERSISTENCE OF HER BAGE VARIETIES OF GRASSES IN MONOCULTURES

Production ability and persistence of 12 species and 25 varieties of g rasses were studied in the years 1987 to 1993 in field trial conducted on sandy loam soil at an altitude of 370 m. Nitrogen fertilization (2 40 kg.ha-1) was applied at three doses (120 + 60 + 60), phosphorus and potassium fertilization at 35.2 kg.ha(-1) and 66.4 kg.ha-1, resp., in the spring. The stands were cut three times. In seven-year observatio n all varieties exhibited a tendency to decrease in total yields of dr y matter. The decrease in the yield was 2.8 t.ha(-1) (Fig. 1) on an av erage. This tendency was, however, principally influenced by two last years with unfavourable course of precipitation and temperatures, for the first cut above all. Yields of dry matter of different varieties i n cuts and in total presents Tab, II. In view of the yield, in our con ditions, the best applied were: Arrhenatherum elatius, Dactylis glomer ata, generic hybrid Hykor (Lolium multiflorum x Festuca arundinacea) a nd Festuca arundinacea. On the contrary, the lowest yields were achiev ed with the Lolium perenne and Agrostis stolonifera. The differences i n yields between varieties within a species were low, only the yield i n Lolium perenne the Roznovsky variety exceed the Tarpan variety by 1. 2 t.ha(-1).To assess the persistence we used a rate of persistence, de termined by us, based upon the percentage of a sown variety in time se quence of monitoring. The variety is perennial if minimum 60% represen tation was achieved in the stand in the fifth utility year and if this representation was achieved in at least one of three following years. As one can see in Tab. II the most persistent species in our conditio ns are as follows: Dactylis glomerata, Arrhenatherum elatius and Festu ca rubra, followed by Festuca arundinacea, Trisetum flavescens, relati vely persistent is also Lolium perenne. The criterion of persistence i s not fulfilled by Phleum pratense, and of a little persistence are Fe stuca pratensis (4 to 5 years) and Poa palustris (3 years).