Abstract
Dry matter accumulation of each part on a main shoot and its partitionings (Δparts/Δshoot, %) were measured at 3 to 7 days intervals during the growing season using the field grown (400 pls./m2) spring wheats, tall Haruhikari and semi-dwarf 2-47. The seasonal pattern of dry matter partitioning of Haruhikari and 2-47 was almost identical (Fig. 2). Based on the pattern, the growth was divided into the following five main phases (Fig. 3). Growth phase I (emergence - flag leaf initiation); dry matter is mainly partitioned to the leaf blade (60-80%). Growth phase II (initiation - emergence of flag leaf); after the start of elongation of the leaf sheath and the culm, the partitioning to the leaf blade decreases and almost ceases during this phase. Growth phase III (flag leaf emergence - anthesis); dry matter is partitioned to the culm and the ear (without grain). The partitioning to the ear almost ceases in this phase. The partitioning to the cellular contents in the culm decreases temporarily at about the time of heading. Growth phase IV (anthesis - milk ripe stage); the partitioning to the grain starts to increase about a week after anthesis. The partitioning to the culm decreases rapidly but that to the cellular contents still continues. Growth phase V (milk ripe stage - maturity); all of the dry matter including reserve material is partitioned to the grain. In 2-47 the partitioning to the culm during the growth phase II was lower, and to the ear during the growth phase III and to the grain during the growth phase IV were higher than those in Haruhikari.
