Submitted to: World Agroforestry Congress
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2004
Publication Date: June 27, 2004
Citation: BURNER, D.M., BELESKY, D.P. 2004. DIURNAL EFFECTS ON NUTRITIVE VALUE OF ALLEY CROPPED ORCHARDGRASS HERBAGE. WORLD AGROFORESTRY CONGRESS. Available: http://conference.ifas.ufl.edu/wca/abstracts/BurnerD2.doc. Technical Abstract: Nonstructural carbohydrates, crude protein, and in vitro dry matter digestibility (IVDMD) are important indices of herbage nutritive value and can exhibit diurnal variation in 'conventional' agronomic systems. Our objective was to determine diurnal trends of nutritive value components in alley cropped orchardgrass (Dactylis glomerata L.) herbage harvested daily from 1-15 June 2001 and 2002 at three times (0500, 1100, and 1700h, CST), from three environments: unshaded control, loblolly (Pinus taeda L.) pine alleys, and shortleaf (P. echinata Mill.) pine alleys. Diurnal effects were defined as the presence of a regression response (P<0.10) with time. Total nonstructural carbohydrates (TNC) and water soluble carbohydrates (WSC) increased linearly in the control and shortleaf pine environments, but not in loblolly pine alleys. Starch increased curvilinearly in pine alleys but not in the control environment. In pine-shaded environments, maximum carbohydrates at 1700h were only 64 to 75% of the control. Crude protein and IVDMD did not exhibit diurnal responses within or across environments. However, mean crude protein decreased and IVDMD increased between AM- and PM-harvested herbage. Shaded orchardgrass herbage averaged 27 to 33% more crude protein, 1 to 2% more IVDMD, 28 to 34% less yield, and 27 to 34% less nonstructural carbohydrates than the unshaded control. Differential responses of nutritive value components among environments were attributed to altered amount and temporal distribution of solar irradiance. The study showed that conventional and alley crop environments elicited different temporal responses in orchardgrass herbage.