Resumo

ROSSI, Ricardo Enrique  e  PRIVITELLO, Liliana M. J.. Defoliation of Digitaria eriantha Steudel: forage production, structure and radiation and water use efficiency. Pastos y Forrajes [online]. 2019, vol.42, n.2, pp. 114-124. ISSN 2078-8452.

In order to evaluate the effect of defoliations on forage production, structure and efficiency of radiation and water utilization of Digitaria eriantha Steudel spp. eriantha cv. Irene, a trial was conducted at the National University of San Luis, Villa Mercedes campus, -San Luis, Argentina-. Three defoliation treatments were evaluated: cycle end (CCC), in mean leaf lifespan (CMLL) and at fixed time every 30 days (CFT). There were significant differences in forage production, total mass and number of cuts (p < 0,05) for CMLL, CCC and CFT (1 100 g DM/m2; 912,693 g DM/m2; and 4, 1 and 6 cuts, respectively). The high frequencies altered the vertical structure, by decreasing stem production; and the horizontal structure, by increasing the tiller density, with lower total biomass production. CFT improved L/S (CFT: 45,45 vs. CMLL: 16,13) and increased tiller density (CFT: 3 773 vs. CMLL: 2 264 tillers/m2). CMLL did not show alterations on the horizontal structure, but the interception (CMLL: 0,85 vs. CCC: 0,97) and radiation capture were weakened with regards to CCC; nevertheless, it generated high leaf production which allowed to maximize the efficiency of water and radiation use (1,38 g DM/m2/mm and 1,30 g DM/MJ, respectively). Defoliation management influences the crop structure and has incidence on the forage offer. Managing forages under morphogenetic concepts induces a balanced utilization of production and quality, and improves the efficiency of the use of environmental resources.

Palavras-chave : biomass; morphogenesis; mowing..

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