NONSTRUCTURAL CARBOHYDRATE ACCUMULATION IN WINTER OAT CROWNS BEFORE AND DURING COLD HARDENING

Most cool-season grasses store large amounts of fructan during fall hardening. Fructan storage has been extensively investigated in most winter cereals, but very little research has been reported in oat (Avena sativa L.). To compare fructan accumulation in crowns of representative winter cereals, two oat, two barley (Hordeum vulgare L.), one wheat (Triticum aestivum L.), and one rye (Secale cereale L.) cultivar were raised under controlled conditions for 5 wk at 15-degrees-C and 3 wk at 2-degrees-C. Starting at the end of Week 4, and at weekly intervals, carbohydrates were extracted from fresh crown tissue and separated by high performance liquid chromatography (HPLC). On a dry-weight concentration basis, oat crowns accumulated significantly less fructan of degree of polymerization greater than 9 (DP > 9) than all other cultivars and significantly more DP3 to DP7 fructan. The presence of large amounts of sucrose and DP3 to DP7 fructan suggested that substrate level was not limiting synthesis of DP > 9 fructan in oat.