Variation of Nonstructural Carbohydrates in Varieties and Individual Plants of Italian Ryegrass : II. Differences between varieties in diploid Italian ryegrass

Abstract

The present experiment was conducted to acertain the differences in the concentrations and the characteristics of nonstructural carbohydrate in diploid varieties of Italian ryegrass at vegetative phase grown in fall. Seventeen diploid varieties of various maturities were used. Nonstructual carbohydrates of plant materials (leaf blade and stem) sampled every 7th days from 30 (Oct.25) to 65 days (Nov.29) after emergence of seedlings were extracted with ethanol solutions varying in concentration, i.e. 85%, 75%, 65%, 55%, and 0% (water) and determined by Anthron method. 1) Distinct varietal differences of nonstructual carbohydrate concentrations from 35% to 47% of the dry matter in stem were observed at the end of the experiment (65 days after emergence). 2) Differences of nonstructural carbohydrate concentrations in stem among varieties were primarily due to the differences in fructosan concentrations, and it is considered that such clear varietal differences as observed in fructosan do not exist in mono- and oligosaccharide concentrations. 3) It is recognized that the higher the concentration of fructosan in the varieties, the higher the degree of polymerization of fructosan is. 4) Relative differences in the concentrations and the characteristics of nonstructural carbohydrate between varieties showed the same trend in stem and leaf and at each harvest time, but the differences were clearer at the later part of the experiment. 5) In general, extremely early and early maturing varieties showed lower nonstructural carbohydrate concentrations, fructosan concentrations, degrees of polymerization of fructosan i.e. lower abilities to reserve carbohydrate than medium and late ones, but some exceptional varieties were also observed. 6) Significant positive correlation coeffecients between nonstructural carbohydrate concentration and specific leaf weight, and between nonstructural carbohydrate concentration and shoot weight were observed at the later part of the experiment and the relationships are discussed from physiological and morphological points of view.