Dynamics of structural traits in two competing C3 grass species: influence of neighbours and nitrogen

GATTI, ML; AYALA TORALES, AT; CIPRIOTTI, PA; GOLLUSCIO RA

GRASS AND FORAGE SCIENCE (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 70 p. 102 - 115

0142-5242

This work analysed the regulatory structural mechanisms involvedin the competitive interactions between the annual grass Bromus willdenowiiKunth. (BW = prairie grass) and the perennial C3 grass Dactylis glomerata L.(DG = orchardgrass) during pasture establishment. Four combinations of species(pure BW, pure DG, DG flanked by BW and BW flanked by DG plants), with andwithout winter nitrogen fertilization, were factorially arranged in arandomized complete block design. Data were recorded at two organizationlevels: tillers (three tiller age cohorts) and target plants. Annual neighbourscaused a decrease in the number of living leaves in tillers of intermediate ageof both species. This structural regulatory mechanism led to a decrease intiller number per plant and, therefore, restricted the development of horizontalspace occupation. Annual neighbours did not cause an increase in tiller size,measured as lamina length or pseudostem height, but decreased root biomass. Asa consequence, annual neighbours did not lead the hierarchy in light capture,but limited species radical colonization and competitive ability for soilresources. Winter nitrogen fertilization only affected tiller size in oldertillers. These findings emphasize the importance of the cultural decisions, assowing densities and nitrogen fertilization, to optimize pasture floristiccomposition.