Resumen

INSUA, J.R; DI MARCO, O.N  y  AGNUSDEI, M.G. Calidad nutritiva de láminas de festuca alta (Festuca arundinacea Schreb) en rebrotes de verano y otoño. RIA. Rev. investig. agropecu. [online]. 2013, vol.39, n.3, pp.267-272. ISSN 1669-2314.

The effect leaf morphoenesis and structure onleaf bades quality was evaluated in summer and autumn regrowths of Festuca arundinacea Schreb. The experiment was conducted in 250 pots arranged in a completely randomised design (n=3) under natural climate conditions, without limitation of water, N and P. In each season swards were sampled 3 times (~300 tillers/replicate) to obtain leaves in 3 ontogenics stages of similar age (just expanded, adult and pre-senescence) corresponding to the 3 first sequentially appearing leaf generations. The leaf elongation rate (LER), leaf app earance interval (LAI), leaf life span (LLS), numb er of living leaves (NLL) and length of the leaf blade and sheath were measured in 5 marked tillers/replicate. In leaf blades, the NDF and the in vitro digestibility (NDFD and DMD) were determined (incubation at 24 h DaisyII digestor). The mo rphog enic variables were evaluated using repeated measures data analysis. Quality traits were analyzed by lineal function with age and leaf length. Comp arisons were made by dummy variable regressions and ANOVA (Tukey). The mean daily temp erature was low er in autumn than in summ er (13±4 vs. 21±3ºC). LER, LLS and LAI were low er (p<0.001) in autumn than in summ er but NLL was similar (p>0.23) in bo th season. Leaf length did not vary during autumn regrow th, but it was shorter than summ er (106±9 vs 239±98 mm ). Leaf blade length increased during summ er amo ng successive leaves of regrow th (~110 mm /generation) in relation (R²=93%) to the prog ressive in crease of the sheath tube length. Autumn leaf blades show ed low er NDF (39,8±0,8 vs 55,3±0,6%), higher NDFD (52,7±1,6 vs 46,8±1,1%) and DMD (69,3±0,9 vs 58,7±0,6%%) than that of summ er regrow th. It is concluded that summ er and autumn regrow ths differ in mo rphog enic, structure and quality variables, and that differences in DM digestibility were associated with the effect of leaf length on NDF and NDFD dynamics.

Palabras clave : Morphogenesis; NDF; DNDF; Leaf age; Leaf length; Sheath.

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