CHANGES IN COLD HARDINESS, ICE TOLERANCE AND TOTAL CARBOHYDRATES OF WINTER WHEAT UNDER VARIOUS CUTTING REGIMES
Fredrick winter wheat was subjected to a number of cutting (defoliation) regimes in controlled environments and in the field in 2 yr to investigate the effects of simulated forage removal on winter survival parameters. In controlled environments, cutting at 4 wk and 8 wk reduced cold hardiness and ice tolerance markedly in plants grown for 5 days, and 14 days at warm temperatures before hardening. Total nonstructural carbohydrates (TNSC) in plant crowns were reduced by all regimes. In the field, the effects of single cuttings were not as large, but generally there were slight reductions in cold hardiness, ice tolerance, and crown TNSC. A slight increase in cold hardiness was associated with multiple cutting in both years but this was not normally reflected in an increase in winter survival. A reduction in ice tolerance by cutting of plants in a plot with low soil moisture was not seen on a periodically flooded plot. Cutting reduced fresh weight of plants and root number, and markedly increased crown moisture content. Overall, despite a variable effect on a number of winter survival parameters, cutting of Fredrick winter wheat appeared to be hazardous to its overwintering potential.Key words: Triticum, acclimation, encasement, clipping, grazing, defoliation