Nonstructural Carbohydrate Reserves in Roots and the Ability of Temperate Perennial Grasses to Overwinter in Early Growth Stages

Abstract

The objective of this study was to determine the concentration of nonstructural carbohydrate (NSC) reserves in the rootat the early growth stage during the cool fall season in four temperate perennial grasses : orchardgrass (Dactylisglomerata L.), timothy (Phleum pratense L.), perennial ryegrass (Lolium perenneL.), and reed canarygrass (Phalaris arundinacea L.) and to examine the relationship between the overwintering ability and the concentration of NSGs. The concentration of NSGs in the root was the highest in reed canarygrass, andit was about three times higher than that in the tops. Timothy stored NSGs in the root at a higher level than orchardgrassand perennial ryegrass. The NSC concentrations in the top were similar in the four grasses. Fructose and especially sucrose concentrations in the root were the highest in reed canarygrass, intermediate in timothy and the lowest in orchardgrass.Also, the reserves in timothy and reed canarygrass were predominantly fructosans with high degrees of polymerization (DP).On the other hand, perennial ryegrass reserves were predominantly fructosans with a low DP. The DP of fructosans in orchardgrass was in between the two. Growth in the dark in spring was the highest in reed canarygrass, the second highest in timothy and the lowest in orchardgrass. From these results we conclude that at the early growth stage reed canarygrass has the highest level of NSGs in the root, followed by timothy, orchardgrass and perennial ryegrass. The wintering ability is regulated mainly by NSC in the roots rather than that in the tops. This is true even at the early growth stage.