Dry matter production and nutritive value of cocksfoot (Dactylis glomerata L.) grown under different light regimes

PERI P.L.; LUCAS R.J.; MOOT D.J.

Silvopastoralism and Sustainable Land Management

CABI Publishing

Lugar: Wallingford; Año: 2005; p. 172 - 173

Dry matter (DM) production, crude protein (CP%) and organic matter digestibility (OMD) were measured in a grazed cocksfoot (Dactylis glomerata L.) pasture (28 day rotation with 21±1 days regrowth) from September 1999 to May 2001 at the Lincoln University silvopastoral experimental area and an adjacent site without trees in Canterbury, New Zealand (43º 38’S and 172º 28’E). The 5.2 ha forest consisted of 200 ten year old Pinus radiata stems per hectare (sph) high pruned up to 6 m with 7 m between tree rows. Four levels of light intensity were compared using a randomised block design with 3 replicates: full sunlight (100% photosynthetic photon flux density-PPFD), open + wooden slats (45% PPFD), trees (60% PPFD) and tree + slats (25% PPFD). The slatted shade structures created a fluctuating light regime with intervals of sunlight and severe shade. The mean annual total DM production was 8.2 t DM/ha/yr in open, 7.3 t DM/ha/yr in open pasture under slatted shade, 6.3 t DM/ha/yr under trees shade and 3.8 t DM/ha/yr in the trees+slats treatment. There was an interaction between treatments and time (rotations). This was expressed by seasonal fluctuations in pasture DM growth rates. CP% increased as PPFD declined. This may be attributed to either a decrease in photosynthates, with a consequent rise in the nitrogen concentration, or to an increase in soil organic matter mineralisation under trees that provided greater nitrogen for grass uptake. In contrast, the intensity of fluctuating shade had little effects on OMD.