Leaf Elongation Rate of Mediterranean and Temperate Tall Fescue Cultivars under Water Deficit

The leaf elongation rate of a temperate (Festuca arundinacea Schreb.) and a Mediterranean (F. arundinacea var. letourneuxiana) tall fescue cultivar in response to water deficit was studied in a glasshouse experiment. Plants of both cultivars were grown in the same containers and received water daily with gradation in intensity of water deficit achieved by varying the daily water ration per container. Leaf elongation rate (LER) was calculated for eight successive subperiods during the application of the water treatments. Under the high temperatures registered in this experiment, the Mediterranean cultivar showed lower LERs and tended to be less affected by a moderate water deficit but more affected by a severe water deficit than the temperate one

Forage Quality and Defoliation Interval in Tall Fescue Cultivars

Past research has shown digestibility decreases along leaf lifespan (LLS) in several grasses (i.e. Groot and Neute-boom 1997; Insúa et al. 2013; Agnusdei et al. 2012). This phenomenon has not yet been quantified in tall fescue (Festuca arundinacea Schreb.). Therefore, additional knowledge on the dynamics of leaf quality decline along LLS is necessary to verify the proper defoliation window necessary to optimize forage quality and production (Fulkerson and Donaghy 2001; Lemaire et al. 2009) in tall fescue. Further, this window might differ between old and new types (i.e. softer vs rough-leaved). The objectives of the study were: (1) to compare leaf quality dynamics of two tall fescue cultivars differing in leaf softness as related to leaf turnover; and (2) to determine the defoliation regime that enables to obtain similar forage quality between cultivars

Simulating Tall Fescue Pasture Growth in Argentina

Tall fescue (Festuca arundinacea Schreb) pastures have the potential to maintain high production rates under limiting climate conditions, especially in dry summers, improving the seasonal distribution of forage growth and year round production (Tharmaraj et al. 2008). The purpose of this work was to test the ability and flexibility of the DairyMod biophysical pasture-simulation model (Johnson et al. 2008), to predict herbage mass accumulation (HMA), of tall fescue pastures from Argentina under several environmental conditions that included different seasons, nitrogen fertilizer application levels and irrigation

State of Knowledge in Tiller Dynamics

Persistence of sown pastures is a concern for pastoral production worldwide. Fundamentally, when a pasture does not persist the problem can be expressed in terms of inadequate new tiller production or excessive tiller death. However, the collection of data to build an understanding of sward dynamics at this level is time consuming. Tiller survival diagrams are presented for a range of temperate and tropical grass species including Lolium perenne, Lolium multiflorum, Festuca arundinacea, Festuca pratensis, Phleum pratense, Bromus willdenowii, Cynodon dactylon, Brachiaria brizantha, Panicum maximum, Chloris gayana and Paspalum notatum. It is shown that each grass has a unique perennation strategy and accordingly unique strengths and weaknesses that confer persistence or lack of persistence in different situations. There is also confusion in extension circles about the trade-off between tiller size and tiller density and how to detect a suboptimal tiller density. Grass swards respond to high herbage mass by increase of tiller size and reduction in tiller density, but reduction in tiller density is often mistaken for sward decline. A distinctionmust be made between size/density compensation and sward decline. Increased understanding of sward dynamics at this level should help in the evolution of management practices that improve persistence on a range of grassland types

Evaluation of Agricultural Production Systems Simulator (APSIM) as yield predictor of Panicum virgatum and Miscanthus x giganteus in several US environments

Simulation models for perennial energy crops such as switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus x giganteus) can be useful tools to design management strategies for biomass productivity improvement in US environments. The Agricultural Production Systems Simulator (APSIM) is a biophysical model with the potential to simulate the growth of perennial crops. APSIM crop modules do not exist for switchgrass and Miscanthus, however, re‐parameterization of existing APSIM modules could be used to simulate the growth of these perennials. Our aim was to evaluate the ability of APSIM to predict the dry matter (DM) yield of switchgrass and Miscanthus at several US locations. The Lucerne (for switchgrass) and Sugarcane (for Miscanthus) APSIM modules were calibrated using data from four locations in Indiana. A sensitivity analysis informed the relative impact of changes in plant and soil parameters of APSIM Lucerne and APSIM Sugarcane modules. An independent dataset of switchgrass and Miscanthus DM yields from several US environments was used to validate these re‐parameterized APSIM modules. The re‐parameterized modules simulated DM yields of switchgrass [0.95 for CCC (concordance correlation coefficient) and 0 for SB (bias of the simulation from the measurement)] and Miscanthus (0.65 and 0% for CCC and SB, respectively) accurately at most locations with the exception of switchgrass at southern US sites (0.01 for CCC and 2% for SB). Therefore, the APSIM model is a promising tool for simulating DM yields for switchgrass and Miscanthus while accounting for environmental variability. Given our study was strictly based on APSIM calibrations at Indiana locations, additional research using more extensive calibration data may enhance APSIM robustness.Fil: Ojeda, Jonathan Jesus. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; ArgentinaFil: Volenec, Jeffrey J.. Purdue University; Estados UnidosFil: Brouder, Sylvie M.. Purdue University; Estados UnidosFil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ciencias Agropecuarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; ArgentinaFil: Agnusdei, Mónica G.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentin