Yield Dynamics and Quality in White Clover and Perennial Ryegrass in the First cut of the Establishment year.

A field trial was carried out in the Vojvodina province, Serbia, during 2009 and 2010 in rainfed conditions. The study assessed the dynamics of yield formation, changes in morphological characteristics, as well as the nutritive values of white clover and perennial ryegrass grown as monocultures. Five varieties of white clover (Chieftain, Susi, Aran, Avoca and Rivendale) and eight of perennial ryegrasses (Cashel, Shandon, Magician, Greengold, Glenstal, Millenium, Sarsfield and Glencar), developed at and provided by Teagasc, Ireland, have been used for this research. After four measurements a significant differences in examined parameters with white clover and perennial ryegrass varieties were registered. In all studied parameters the highest values were recorded in the fourth measurement. The stolon length ranged from 1.4 cm (Avoca) to 4.1 cm (Chieftain). Susi had the highest number of stolons (2.1), and Rivendale had the lowest (0.9) but also the highest number of leaves per stolon (3.7). The leaf length ranged from 6.1 cm (Avoca) to 19.3 cm (Aran). Concerning ryegrass, the number of lateral shoots ranged from 2.8 (Millenium) to 4.8 (Magician). The highest number of leaves per shoot was in Cashel (4.8), and the lowest was reported for Millenium and Greengold (3.3). The average shoot height to the first leaf varied between 3.2 cm (Glenstal) and 4.4 cm (Cashel). The highest yield of white clover was achieved by Rivendale (1.19 t ha-1), while the highest yield of perennial ryegrass were recorded by Millennium (8.26 t ha-1) and Magician (8.03 t ha-1). The average crude protein content was higher in white clover (22.8 %) than in perennial ryegrass (12.8 %), while the crude fibre content of white clover and perennial ryegrass were 18.1 and 34.7 %, respectively. These parameters led to a lower digestibility in perennial ryegrass, reflected through the monitored parameters of NDF and ADF