DRY-MATTER ACCUMULATION AND PARTITIONING AND ITS RELATIONSHIP TO GRAIN-YIELD IN WHEAT

Total crop dry matter (DM) production and its components, remobilisati on of stem reserves, and the relation of these to grain yield were stu died in 10 wheat cultivars sown at Walpeup, Boort, and Horsham in the north-western Victorian wheatbelt. Between sites, all DM components de creased in the order Horsham > Boort > Walpeup. Differences between Bo ort and Walpeup were not always significant. Total DM at anthesis for Walpeup and Boort was in a similar range, and less than that for Horsh am. Yields increased in the order Walpeup < Boort < Horsham. When data from the 3 sites were combined, leaf stem (excluding cv. Argentine IX ), and total DM were related to grain yield. Within sites, ear DM at a nthesis was related to grain yield. Grain yield far all cultivars at H orsham and Walpeup and 5 cultivars at Boort was greater than the incre ases in crop DM from anthesis to maturity, indicating that pre-anthesi s stored assimilates (stem reserves) were used for grain filling. Post -anthesis decrease in stem weight was inversely related to grain yield only at Horsham, which supports the view of utilisation of stem reser ves for grain filling at this site. At Boort and Walpeup there was a s imilar negative trend, but values for 2 cultivars at each site were ou tliers, which weakened the trend. The wide adaptability of the Austral ian cultivars used in this study may be related to the differential re mobilisation of stem reserves at each site. A measure of yield stabili ty, however, was not related to stem weight loss during the grain-fill ing period.