COS 106-2
Genotypic diversity and forage productivity:  Meeting the challenges of increased demand and climate change in perennial forage systems

Thursday, August 14, 2014: 8:20 AM
Bondi, Sheraton Hotel
Fredric W. Pollnac, Natural Resources and the Environment, University of New Hampshire, Durham, NH
Nicholas D. Warren, Natural Resources and the Environment, University of New Hampshire, Durham, NH
Richard G. Smith, Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH

In coming years, agroecosystems of the world will need to be modified and/or expanded to meet increasing food demands while simultaneously adapting to and/or mitigating the effects of climate change. Incorporating genotypic (cultivar) diversity has resulted in increased productivity in many types of production systems, but information from perennial forage systems is lacking. In addition, the ability of genotypic diversity to 1) overcome the challenges of an increasingly variable growing environment, and 2) increase the efficiency of pastures in current climate conditions remains unclear. This project's objective was to investigate the effects of genotypic diversity in a Lolium perenne forage system in terms of forage productivity and potential grazing season extension. In August of 2011, plots were established using six L. perenne cultivars to establish one cultivar, three cultivar, and six cultivar treatments in a randomized complete block (RCB) design. In August of 2012, plots were established at a separate site to evaluate the performance of thirteen L. perenne cultivars, as well as six purposeful mixes of three to five cultivars based on heading date and winter hardiness in a RCB design. Biomass data were collected from each plot at each site in all growing seasons after the establishment year.


For the first experiment, L. perenne dry biomass (yield) was greater in three cultivar mixtures (p = 0.01) and six cultivar mixtures (p = 0.005) than in single cultivar plots, and this difference was more pronounced in the initial growing season than in the second growing season. In addition, calculated yield indices showed that yield of cultivar mixtures was greater than predicted based on the sum of individual component cultivar yields during both years (p <0.01), and that there was no significant difference between the mixture yield and that of the highest yielding cultivar in the mixture on average. Preliminary results from the second experiment indicate that L. perenne late season growth rate (cm/day) is greater (p = 0.06) for one mixture than it is for the recommended cultivar for the area. These results highlight the potential for cultivar diversity in L. perenne based systems to increase overall forage productivity, and to potentially extend the effective duration of pastures later into the fall in the Northeast United States. Further research will indicate if these results hold for other forage species, and if they translate into more stable forage yields from year to year in the face of climatic variation.