Changes in cellular and water soluble sugar contents during grain filling period in three parts of main culm of spring wheats.

Changes in culm contents, cell wall constituents, net cellular matter and water soluble sugar content (WSC) were determined from anthesis to maturity in three parts of the main culm, peduncle, second and lower internodes, for three spring wheat varieties, tall Haruhikari, semi-dwarf Haruyutaka and tall late Selpek. After anthesis cell wall constituent and net cellular matter increased in peduncle and the second internode, associated with the elongation, but a little in the lower internodes, of which elongation has almost ceased at anthesis (Fig. 2). Contrary to this, WSC as a storage material increased in each part until milk ripening, decreasing to almost zero at maturity, presumably due to translocation to the ear. WSC has been rapidly accumulated before anthesis in the lower internode, but started to store at about anthesis in peduncle and the second internode, and attained the maximum at about a week before milk ripening in the lower internodes, just at the milk ripe stage in the second internode and several days after milk ripening in peduncle. For all varieties the percent WSC was higher in the second internode and the amount of WSC in the lower internodes was more than in peduncle and the second internode at milk ripe stage, suggesting that the second and lower internodes were main storage organs. In addition the percent and amount of WSC were larger for semi-dwarf Haruyutaka than for tall Haruhikari and Selpek.