Improving Silage Yield and Seasonal Distribution of Ryegrass in the Southeastern USA.
Ann Blount, Univ of Florida, N. Florida Research and Education Ctr, 3925 Hwy 71, Marianna, FL 32446-790, Cheryl Mackowiak, Univ of Florida-NFREC, 155 Research Rd., Qunicy, FL 32351, and Gordon Prine, Univ of Florida, 304 Newell Hall, Agronomy Dept, Gainesville, FL 32611-0500.
Extending the seasonal forage production of annual ryegrass (Lolium multiflorum L.) will directly benefit dairy operations utilizing ryegrass as silage. Annual ryegrass cultivars in the southern USA tend to be mid- to late-season forage producers. Ryegrass cultivars selected for early-season forage production will accelerate greenchop or silage harvests for the dairies. Additionally, environmental impacts of nitrates on water quality in this region makes annual ryegrass an attractive choice for processing large quantities of water and nutrients. Previously, a two-year on-farm study that newly developed, disease resistant cultivars were more productive under high management dairy silage systems. However these newer cultivars produced this yield too late in the season to allow for double-cropping corn planted in the early spring. To improve the seasonal distribution of ryegrass silage, a study was initiated in 2005 and 2006 comparing an early, disease-resistant experimental ryegrass line, MAR Early 4X, with Jumbo and Marshall ryegrass. March silage harvest of MAR Early 4X was greatest at 7.1 Mg h-1 compared with 5.6 Mg h-1 for Jumbo and 4.5 Mg h-1 for Marshall. Final May yields were statistically similar for MAR Early 4x and Jumbo at 5.1 and 3.7 Mg h-1, respectively. Marshal had the lowest yield at 1.8 Mg h-1. Gray leaf spot disease ratings were similarly low among cultivars in March but Jumbo and Marshall ratings increased from 2 to 5 by the May harvest, with MAR Early 4x remaining unchanged. 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.