Effect of Ploidy on Quality of Tall Fescue, Italian Ryegrass × Tall Fescue and Tall Fescue × Giant Fescue Hybrids

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Abstract
Selected quality parameters were measured for forage leaf tissue from a spaced-plant nursery. The genotypes used were Ky 31 tall fescue and hybrids of Italian ryegrass (Lolium multiflorum Lam.) × tall fescue (Festuca arundinacea Schreb.) and tall fescue × giant fescue [Fescue gigantea (L ) Vill.]. Hybrid ploidy ranged from 2n = 28 to 84 chromosomes. Forage quality was characterized by neutral detergent fibre (NDF), acid detergent fibre (ADF), total soluble carbohydrates (TSC) nutritive value index (NVI), hemicellulose, and in vitro dry matter disappearance (DMD). Quality of tall fescue, as measured by increased DMD, was improved by hybridization with giant fescue. Improved DMD and NVI correlated with lower NDF and ADF in the hybrids. A few hybrids of Italian ryegrass × tall fescue (2n = 28) were higher in some quality parameters than Ky 31. Tall fescue × giant fescue hybrids (2n = 80 to 84), as a group, had significant quality improvement over Ky 31 in higher DMD and NVI and lower NDF and ADF. While some individual hybrids within each group were significantly higher in quality, only the 2n = 80 to 84 chromosome group was consistently higher than Ky 31. Prediction equations for DMD, NDF, and ADF were established based on solvent extraction with near-infrared reflectance spectroscopy (NIRS). Linear correlation coefficients between chemical measurement and NIRS for each quality parameter were 0–95 or higher.