Growth, Water‐Use Efficiency, and Digestibility of Crested, Intermediate, and Western Wheatgrass

Abstract

Relationships between dry matter distribution among plant components, growth rates, in vitro digestible organic matter (IVDOM), and water-use efficiency (WUE) have not been defined for cool-season wheatgrass species grown on the Northern Great Plains. Three cultivars each of crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.}, intermediate wheatgrass (Elytrigia intermedia (Host) Nevsk: Syn: A. intermedium (Host) Beauv.}, and western wheatgrass (Pascopyrum smithii (Rhdb.) LOve Syn: A. smithii Rydb.} were field grown and sampled over a 3-yr period to define these relationships. The soil was a Parshall fine sandy loam (coarse-loamy, mixed Pachic Haploboroll). Forage was harvested at three dates to measure IVDOM, WUE, forage yield, leaf area index (LAI), and leaf and stem dry matter. Significant differences were mainly present among cultivars of western wheatgrass compared to those of crested and intermediate wheatgrass. 'Rodan' western wheatgrass partitioned more dry matter into stems than leaves, which resulted in lower LAI, leaf/stem ratio (LSR), and IVDOM. However, Rodan had higher WUE and forage yield than did 'Flintlock' and 'Rosana' western wheatgrass. Although forage yield and IVDOM differed among western wheatgrass cultivars, there were no differences in total digestible organic matter. Growth analysis showed Rodan western wheatgrass to be more efficient than Flintlock and Rosana in accumulation of dry matter per unit of photosynthesizing leaf surface. These results suggest that partitioning of dry matter into leaves and stems is a primary factor in determining WUE and digestibility, especially for western wheatgrass.of cool season grass species and varieties using in vivo and in vitro techniques. Agron. J. 63:241-245.

Response of Perennial Cool‐Season Grasses to Clipping in the Southern Plains

“…Western wheatgrass, native to North America, is generally considered less productive than introduced species of the Triticeae tribe (Schuster and de Leon Garcia, 1973; Frank and Karn, 1988; Asay et al, 2001). However, there are examples in which production from western wheatgrass was equal to or greater than production from intermediate wheatgrass (Launchbaugh, 1958; McGinnies et al, 1963), tall wheatgrass (Holechek et al, 1989), or Russian wildrye (Newell and Keim, 1947).…”

“…In June, IVDDM concentration was similar among grass species for all years except 2000 when intermediate wheatgrass was lower than the other three grasses. White and Wight (1981) found Russian wildrye had higher IVDDM than intermediate wheatgrass in 3 of 8 yr while Frank and Karn (1988) reported higher in vitro digestible organic matter concentration in intermediate wheatgrass relative to western wheatgrass.…”

Production characteristics of the mixed prairie: constraints and potential

“…Although root production is greater in warm vs cool climates, root biomass is often greater in the latter due to reduced turnover which is a function of temperature (Redmann 1975, Sims andCoupland 1979). Root turnover on the mixed prairie was estimated to be 18% (Sims and Coupland 1979) while 62% of Ihe roots were functional in a blue grama communiry (Singh and Coleman 1974 (Frank and Karn 1988). In another test, crested wheatgrass was more WUE (4.1g kg-'; than wesrern wheatgrass (2.6 g kg -t) which was associated with reduced LAI.…”

Morphology of Panicum genotypes submitted to periods of cessation of irrigation

“…This plant originates from an environment of low rainfall (Table 1), therefore, this result may be related to adaptations for limited water availability in the soil in order to increase their persistence in the pasture. Frank and Karn (1988) reported that genotypes with high growth rates are less tolerant to drought. It is noteworthy that the municipality of São Bento do Una has the highest intensity and frequency of droughts among the evaluated sites.…”