STRAW QUALITY OF 10 WHEAT CULTIVARS UNDER CONVENTIONAL AND NO-TILL SYSTEMS

Straw of small-grain cereal is an important source of feed for mainten ance of ruminant livestock. Information on the nutritional quality of wheat (Triticum aestivum L.) straw under conservation tillage system i s limited. Grain and straw (leaves and stem) samples were obtained fro m a previous tillage by cultivar field study conducted on a Bethany si lt loam (fine, mixed, thermic Pachic Paleustoll) from 1984 to 1987 nea r El Reno, OK, to determine the straw quality of 10 hard red winter wh eat cultivars grown under conventional (moldboard plow) and no-till sy stems. Straw was analyzed for neutral-detergent fiber (NDF), acid-dete rgent fiber (ADF), lignin (LIG), crude protein (CP), and in vitro dry matter digestibility (IVDMD). Fiber (ADF and NDF) and LIG concentratio ns of straw from the early-maturity cultivars were higher (P less-than -or-equal-to 0.05) than medium and late maturity cultivars. Crude prot ein (5 to 12 g kg-1) and IVDMD (25 to 39 g kg-1) concentrations were l ower in early-maturing than in medium- and late-maturing cultivars amo ng years. Neutral-detergent fiber and ADF concentrations of all cultiv ars were not affected by tillage system; however, LIG of early-maturin g cultivars (Chisholm and Vona) grown under a no-till system was 9 to 24 g kg-1 lower in 1985 and 1986 than in conventionally tilled plots. In vitro dry matter digestibility of all cultivars was not consistentl y affected by tillage system: no significant difference in 1984, while straw IVDMD from no-till plots of all cultivars averaged 9 g kg-1 low er in 1985 and 13 g kg-1 lower in 1986, compared with conventionally t illed plots. Straw quality of the 10 wheat cultivars varied among matu rity groups, but the effect of tillage system on straw quality was min imal.