Abstract

PETIGROSSO, L.R et al. Interacción entre festuca alta infectada con endófito y Lotus tenuis bajo dos frecuencias de defoliación. RIA. Rev. investig. agropecu. [online]. 2018, vol.44, n.1, pp.41-48. ISSN 1669-2314.

The toxicity of tall fescue infected with asexual endophyte Epichloë coenophiala can be attenuated when the species is sown in mixture with legumes. The aim of this work was to simulate the establishment of pastures of infected tall fescue (Fa), both pure and consociated with Lotus tenuis (Lt), and to evaluate the effect of two defoliation frequencies on aerial biomass production and the number of tillers in Fa and stems in Lt during the year of implantation. The experiment was conducted outdoors in plastic containers (0.6 m x 0.4 m x 0.2 m). On 24 February 2015, 52 seeds of infected Fa and 12 seeds of Lt were sown in each container for the mixed pastures (i.e. 64 plants in total), and the same number of seeds of each species was used for the respective monocultures (i.e. 52 and 12 plants in Fa and Lt monocultures, respectively). The controlled experimental factor was the defoliation frequency (70 mm cutting height): high and low (every 7-9 and 14-21 days, respectively, the interval depending on the season). A completely randomized experimental design with 3 replicates and repeated measurements in time was used (18 containers in total). Accumulated aboveground harvested biomass of each container and the number of tillers of Fa and stems of Lt plants were determined during the experimental period. Accumulated biomass of Fa and Lt in monocultures and mixtures during the experimental period varied depending on the defoliation frequency and/or type of pasture. In general, and according to the growing season of the species, at the beginning of the experimental period Fa monocultures and mix pastures accumulated more biomass than Lt monocultures, while the opposite took place by the end of it. Tillers density in Fa and stems density in Lt for both monocultures and mix pastures were not affected by defoliation frequency, except by the end of the experimental period when the stems density in Lt monocultures was higher than the observed in mix pastures. Conversely to what it was observed previously, at the end of the experimental period tillers density in Fa and stems density in Lt, for both monocultures and mix pastures, tended to be higher with low than with high defoliation frequency.

Keywords : Schedonorus arundinaceus; Epichloë coenophiala; Legume; Competition.

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