Resumen

INSUA, J.R; DI MARCO, O.N  y  AGNUSDEI, M.G. Longitud de la vaina como determinante de la calidad de hojas de festuca arundinacea durante un período de rebrote. RIA. Rev. investig. agropecu. [online]. 2014, vol.40, n.2, pp.202-207. ISSN 1669-2314.

Leaf blade nutritional quality of two regrowths of Festuca arundinacea differing in stubble height (40 mm and 100 mm) was evaluated during spring-summer (2011-2012). The experiment was conducted outdoor without limitations of water, N and P, in 500-pots arranged in a completely randomised design (n=3). The leaf elongation rate (LER), leaf appearance interval (LAI), leaf life span (LLS), number of living leaves (NLL) and length of the leaf blade and sheath were measured in 15 marked tillers per treatment. In parallel, three destructive harvests of 6 pots/treatment/replicate were performed when two, three and four leaves were accumulated per tiller (2L, 3L and 4L, respectively). The NDF, NDF digestibility (NDFD) and the DM apparent digestibility (DMD) were determined in leaf blades, by in vitro 24 h-incubation (DaisyII digestor). Parameters of morphogenesis were evaluated using repeated measures analysis and those of quality were analysed by regression functions with leaf age and length and dummy variables. The mean values of treatments in each leaf stage were compared by ANOVA (Tukey). The mean daily temperature of regrowth was 19.7±3 °C. Stubble height affected leaf morphogenesis, structure and quality. The lower stubble height regrowth showed a shorter sheath tube length (65 vs 130 mm), leaf blade length (444 vs 629 mm), LER (16 vs 25 mm.day-1) and LAI (275 vs 354°Cd), but similar LLS (629±34 GDD). It is also had higher NLL (2.5 vs 2.0) and leaf blades of higher quality. NDFD increased 16% and DMD 9%, but NDF did not differ between treatments (62.3±0.6%). It is concluded that changes occasioned by reduction of sheath tube length on leaf morphogenesis, sward structure and fiber digestibility favour the nutritional quality of regrowth.

Palabras clave : Stubble height; LLS; NDF; NDFD; Leaf age; Leaf blade length.

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