Diapositiva 1

1
Improving Silage Yield and Seasonal
Distribution of Ryegrass (Lolium multiflorum L.)
in the Southeastern USA
Ann Blount1, Cheryl Mackowiak1 and Gordon
Prine2 1University of Florida NFREC-Marianna
and Quincy, Florida 2University of Florida,
Gainesville, FL
Results and Discussion Early 4x is an
experimental line developed for early-season
forage production, crown rust and gray leaf spot
resistance. Total seasonal yield from Early 4x
was nearly twice the yield of Marshall. Early 4x
produced 15.0 Mg ha-1 dry matter compared with
11.2 Mg ha-1 for Jumbo and 8.3 Mg ha-1 for
Marshall (Fig. 1). There were no significant
differences between the March and May yields.
Gray leaf spot disease ratings were similarly low
among cultivars in March but the average
Marshall rating increased from 2 to nearly 8 by
the May harvest (Fig. 2). Early 4x and Jumbo
disease ratings remained similarly low. Forage
quality as measured by in vitro organic matter
digestibility (IVOMD) was over 77 for all
cultivars at the March harvest (Fig. 3). Forage
quality declined below 65 by the May harvest,
with Early 4x having the lowest average value at
58. An added benefit of using higher yielding
forages may be their ability to remove more
nutrients from systems receiving effluents or
other wastes. The Early 4x removed a total of 63
kg P ha-1 (144 kg ha-1 P2O5), whereas Marshall
removed only 36 kg P ha-1 (82 kg ha-1 P2O5).
Tissue content was nearly 0.5 in many cases for
Early 4x and Jumbo.
Introduction Extending the seasonal forage
production of annual ryegrass (Lolium multiflorum
L.) utilized as silage will directly benefit
southern dairy operations. Annual ryegrass
cultivars in the southern USA tend to be mid- to
late-season forage producers. Early season forage
production will accelerate greenchop or silage
harvests for dairies. Additionally,
environmental impacts of nutrients on water
quality in this region makes annual ryegrass an
attractive choice for processing lagoon effluent.
A north Florida dairy utilizes annual ryegrass as
a significant part of their livestock diet for
much of the calendar year using a sprayfield
production system. It was previously shown that
disease resistant cultivars were more productive
under their high management dairy silage system.
However, production was too late in the season to
allow for double-cropping corn.
Objectives Evaluate silage production of
improved ryegrass cultivars under a sprayfield
production system. Assess nutrient removal based
on biomass harvested from the field.
Materials and Methods First year study Winter,
2006 Fertilizer Lagoon effluent via pivot
irrigation Seeding rate 56 kg ha-1 Cultivars
Marshall, Jumbo and experimental Early 4X Tissue
P analysis of oven-dried, digested forage was by
ICAP.
Fig. 3. Forage quality (IVOMD) comparisons found
lower IVOMD at the May harvest. Bars with
letters represent differences among cultivars at
P 0.05. There were no forage quality
differences among cultivars at the May harvest.
Fig. 4. Forage removal of soil P, based on the P
analysis of the harvested forage and forage dry
matter at each harvest. Bars with letters
represent differences among cultivars at P
0.05.
Conclusions These data support that forage yield
and the distribution of that yield may be
improved through breeding and selection for
cultivars that fit the desired time-frame for
greenchop and silage production on southern US
dairies. Selection through plant breeding for
earlier growth and high tonnage is providing new
cultivars, such as Early 4x, for high nutrient
input forage systems.
Fig. 1. Dry matter yield in the spring of 2006
from 3 annual ryegrass cultivars. There was no
differences between the March and May harvest.
Bars with letters represent differences among
cultivars at P 0.05.
Fig. 2. Incidence of gray leaf spot disease
using a rating scale of 1 to 9, where 1 no
symptoms and 9 leaf death. Bars with letters
represent differences among cultivars at P
0.05. There were no disease rating differences
among cultivars at the May harvest.