RELATIONSHIPS BETWEEN PHYSICAL AND CHEMICAL CHARACTERISTICS OF 3 SANDHILLS GRASSES

Physical and chemical traits of grass tillers can be strongly correlat ed. Understanding such patterns would help define physiological develo pment of tillers and changes in quality of forage in Sandhills grasses . Physical and chemical traits were quantified for sand bluestem (Andr opogon hallii Hack.), prairie sandreed [Calamovilfa longifolia (Hook,) Scribn.], and little bluestem [Andropogon scoparius (Michx.)] on 3 si tes at 4 times (mid-June, July, August, and October) during the 1990 a nd 1991 growing seasons. Thirty tillers were identified along two, 50- m transects (30 tillers/species/transect) within each site and tiller growth stage, length, and erectness determined. Tiller weight was defi ned from plants collected within 20 quadrats/site, Protein content, in vitro dry-matter digestibility (IVDMD), hemicellulose, total cell. wa ll, acid detergent fiber (ADF), lignin, ash, fetal chlorophyll, and no nstructural carbohydrates (TNC) were determined on plant materials rep resenting the dominant growth stages. Relationships among traits of th e 3 species were determined by Spearman's rank correlation, and among linear combinations of sets of chemical and physical traits by canonic al correlation analysis. Tiller length, weight, and growth stage were positively correlated (P < 0.05) and increased with length of growing season. Crude protein, digestibility, hemicellulose and chlorophyll we re positively correlated and declined, but negatively correlated with lignin and ash, Significant (P < 0.05) correlations between the first canonical variates indicated a strong relationship between tiller matu rity/architectural development (physical canonical variate) and forage quality (chemical canonical variate) was present, and large portions of variance in the original variables was defined, Results of this stu dy defined large-scale multi-dimensional relationships between declini ng forage quality and increasing tiller maturity/architectural develop ment, previously noted in many univariate analyses of limited sets of characteristics.