Abstract
The present experiment was conducted to ascertain the differences in Total Nonstructural Carbohydrate concentration (TNC%) in stem beetween high and low snow endurance varieties in diploid and tetraploid Italian ryegrass in vegetative phase grown under low air temperature in fall. In order to make use of some properties as the indices of the nonstructual carbohydrate concentration, the relations of TNC% to some morphological and physiological traits were also investigated. High snow erdurance varieties showed significantly higher TNC% of dry and fresh matter than low snow endurance varieties both in diploid and tetraploid Italian ryegrass. It is considered that the nonstructural carbohydrate play an important role in snow endurance as the source of energy for the plants surviving under snow. The significant positive correlations between TNC% and dry matter percentage, and significant negative correlations between TNC% and Total Nitrogen percentage (TN%) were observed, indicating the possibilities of these properties to be used as the indices of nonstructural carbohydrate concentration. At the same time, it was also confirmed that tetraploid variety showed significantly higher intercept in the linear regression of dry matter percentage on TNC% than diploid variety. This result indicates that in case of using the dry matter percentage as the index of the nonstructural carbohydrate concentration, diploid and tetraploid varieties must be dealt with separately. In the linear regression of TN% on TNC%, no significant differences were observed both on the slope and intercept between diploid and tetraploid varieties. Correlation coefficient of specific leaf weight to TNC% was significantly high in diploid varieties, but not in tetraploid.
