Relationship of Morphological Characteristics to Forage Quality in Quackgrass1

Abstract

The excellent adaptation of quackgrass [Elytrigia repens (L.) Nevski] in the North Central region of the USA suggests that this species may have potential as a cultivated forage. The objectives of this experiment were to characterize variation among quackgrass genotypes for in vitro dry matter disappearance (IVDMD), neutral detergent fiber (NDF), N, and several morphological characters and to determine whether quality and morphological characters were correlated. Thirty‐four genotypes of quackgrass, randomly collected in Wisconsin, were planted in four replicates on a Pillot silt loam soil (Typic Argiudoll). Vegetative growth was sampled from each genotype at the early heading stage of development in 1980, 1981, and 1982 and analyzed for IVDMD, NDF, and N. Genotypic variation averaged over years was significant for leafiness, leaf angle, leaf width, culm diameter, rhizome spreading vigor, growth habit, and all quality measurements except NDF. Genotype ✕ year interactions were significant for all characters except culm diameter and spreading vigor. Genotypic variation within years was significant for all characters in all years except for spreading vigor in 1980 and 1982, and IVDMD in 1982. Three‐year genotype means ranged from 645 to 731 g kg 1 for IVDMD, 555 to 609 g kg−1 for NDF, and 24.6 to 33.5 g kg−1 for N, and were significant except for NDF. Only growth habit was correlated with any quality character. The more prostrate plants were higher in N and IVDMD. It appears that sufficient genotypic variation exists within this population to improve IVDMD and N, and perhaps NDF. Morphology was not correlated well enough with quality in this study to be used in selection. Genotypes should be evaluated for quality for a minimum of 2 yr. Total N would be the best selection criterion among those investigated, due to its larger repeatability and lower genotype ✕ year interaction.