Forage Accumulation and Quality of Three Contrasting Ecotypes of Tall Fescue (Schedonorus arundinaceus) Managed under Frequent Defoliation

Abstract

In the past, tall fescue ecotypes were compared under intermediate management defoliation frequency, but now has station, Argentina (-33 ° 56 'S, -60 ° 33' W) in autumn 2016, on a typical Argiudoll soil. The treatments were cultivars representing three ecotypes of tall fescue: (i) - Mediterranean (cv. Flecha), (ii) - Intermediate (cv. Royal Q 100) and (iii) - Continental (cv. Lujan INTA). Each plot consisted of 7 rows 6.0 m long, 0.2 m apart (8.4m2 plot size) arranged in a randomized complete block design with 4 replicates. The first cut was done at the end of September when pastures reached > 90 % of soil cover. The following six cuts were done when thermal time was 550°±50°C degree days (base temperature=4°C). The forage accumulation was determined by cutting with a mowing machine the central 5 m2 of each plot, at a height of 0.05 m. A sample (0.250 g) was taken to analyze in vitro dry matter digestibility (IVDIG), crude protein (CP), neutral detergent fiber (NDF) and NDF digestibility (NDFDIG). Mixed model was applied to consider ecotype and time effects. Ecotype*time interaction was significant for all variables (p< 0.0001) except for forage accumulation. The values ranged between 491 and 2,625 kg DM ha-1 for forage accumulation, while IVDIG ranged between 57.2 and 68.7%, CP between 11.5 and 19.1%, NDF between 45.5 and 62.8% and NDFDIG between 26 and 65.3%. The Mediterranean ecotype produced less forage but in many cuts with higher CP. In many cuts, IVDIG was higher in the Continental ecotype associated with less leaf diseases.