Effects of defoliation frequency and nitrogen fertilization on the production and potential for persistence in Dactylis glomerata sown in multi-species swards.

GATTI MARÍA LAURA; AYALA TORALES ALEJANDRA; CIPRIOTTI PABLO; GOLLUSCIO R.A

GRASS AND FORAGE SCIENCE (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 72 p. 489 - 501

0142-5242

Management decisions should facilitate the dominanceof C3 perennial grasses over annuals. This study examined the effects of defoliation frequencies and nitrogenfertilization on the productivity and potential for persistence of Dactylis glomerata L. (DG cocksfoot, perennial) in multispecies swards. Treatments wererandomly applied to 24 mini-swards of DG + Bromuswilldenowii Kunth (BW prairie grass, annual/biennial)in a factorial design of four defoliation frequencies,based on number of leaves per tiller, by two nitrogenwinter fertilization levels (N or N+). Regardless of fertilization, very frequent and repeated defoliations wererelated to decreases of about 43% of aboveground biomass and frequent defoliations with decreases of about44% of vegetative tillers associated with horizontalspace occupation and potential for persistence. Nevertheless, differences in DG aerial productivity orreserves were not detected between frequent and optimal defoliation frequencies. Combined effects of N+and optimal frequency were related to root biomassincrement of about 200%, compared with frequentdefoliation, associated with competitiveness and survival of DG. Optimal defoliation frequency wouldhave ecological but not production advantages, compared with frequent defoliations. The results arediscussed in terms of more objective decision-makingin the management of multispecies swards.