Acumulacion de forrajimasa e indicadores de calidad de gramíneas perennes estivales fertilizadas

Abstract

Se determinó el efecto de la defoliación sobre rendimientos, composición y proteína bruta (PB) de Bothriochloa sp (cv. Dahl, Spar, Plains) y Bouteloua curtipendula (cv. Vaughn. Frecuencias de defoliación de 28, 35 y 42 días (Tl, T2 y T3) y corte único (T4) y participantes se dispusieron en un diseño de parcelas divididas. Se determinaron: acumulación de MS de planta entera (RPE) y lámina RF)-kg.ha1.año1-, PB en F ((por ciento)), rendimiento de PB (RPB,kg.ha1.año1) y valores medios de tasa de acumulación (tc, kg.ha1.dia1). Los datos se analizaron por el procedimiento GLM (SAS) y contraste de medias con Tukey (p0,05). Valores acumulados totales: Dahl tuvo RF superiores a los restantes participantes; entre tratamientos, con excepción de Dahl los valores inferiores de RF, PB y RPB correspondieron a T4. Valores discriminados por corte: en T1, T2 y T3 las tc mas elevadas correspondieron al corte 2. El corte 1 tuvo menor PB, por senectud de parte del F. Se destacó Dahl por su RF, con defoliaciones cada 28, 35 o 42 días, que permiten la cosecha de F con al menos 8(por ciento) de PB.

The essay was can-ied out to determine the effect of defoliation frequency on yields, dry matter composition and protein content in three Old World bluestems cultivars (Bothriochloa sp cv. Dahl, Spar, Plains) and one of sideoats grama {Bouteloua curtipendula (Mich.) Torrey cv. Vaughn) on the growth season. Defoliation (4 frequencies) and participants were arranged within a split plot design. Yields of whole plant dry matter (WPY) and blade (LY) -kg.ha1.y-1, crude protein content In L (CP, %), yield of CP of L (CPY, kg.ha1.y-1) and mean values of growth rate (gr, kgDM.ha1.d1) for WP and L were measured. Data were analyzed by proc GLM (SAS) and means were compared by Tukey test (p0,05). Accumulated mean values: Dahl had the highest LY; between treatments, except Dahl, the lowest values Of LY,' CP and CPY corresponded to T4 (single cut). Discriminated cutting values: in Tl-T2 the WPY, LY and CPY of the 2 first cuttings were significativety higher (even with exceptions), corresponding the upper cut rates to cutting 2. CP content was lowest in cutting 1, by senescence of L. It is concluded that cv. Dahl is the best of the forage species and cultivars under evaluation, due to its high LY when defoliated at frequencies of 28, 35 or 45 days. At these frequencies, the leaves harvested a CP concentration of at least 8%.