Yield and Quality of Forage from Orchardgrass selected for Resistance to Purple Leaf Spot
1987
Oberheim, Robert L. | Berg, Clyde C. | Sherwood, R. T. | Zeiders, K. E.
The development of forage species with resistance to leaf diseases appears to be the only feasible method of limiting yield and quality losses. Our goal in this study was to determine if forage yield and quality were inadvertently changed during three cycles of recurrent phenotypic selection in orchardgrass (Dactylis glomerata L.) for resistance to purple leaf spot (caused by Stagonospora arenaria Sacc.), and to determine if variability existed within the third cycle for yield and quality traits. Twelve disease resistant half-sib families from Cycle 3 were compared with a composite of the original entries (Cycle 0), with a composite of Cycle 3, and with two commercial cultivars in broadcast seeded plots harvested three times in 1982 and twice in 1983. Very little purple leaf spot occurred in the plots. Averaged over 2 yr, Cycle 3 was later in maturity than Cycle 0 (P<0.01), and Cycle 3 had slightly lower protein content (P<0.05) at first harvest than Cycle 0. Although ranges were usually small, significant differences were found among half-sib families for crude protein (CP), in vitro dry matter disappearance (IVDMD), acid detergent fiber (ADF) at first and second harvests, and neutral detergent fiber (NDF) at first harvest (averaged over years). Significant differences were found among half-sib families at the third harvest in 1983 for CP, IVDMD, ADF, and NDF. Half-sib families varied in dry matter yield only for the first harvest. When entries differed significantly, the yield, CP, or IVDMD of one to several resistant half-sib families equalled or exceeded that of Cycle 0, Cycle 3, or the cultivars. Breeding for resistance to purple leaf spot did not result in appreciable changes in the traits measured. However, the selected population contained some genetic variability for each quality trait.
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