Effects of grain shape and size on milling yields in wheat. I. Theoretical analysis based on simple geometric models

Abstract

Simple geometric models of wheat grains have been analysed to determine the effects of changes In shape and size on volume per unit surface area and hence potential milling yield. These analyses suggest that substantial changes In grain volume would have a greater effect on milling yield than would changes in grain shape. The shape and size of kernels of current Australian cultivars differ markedly from the optimum required to maximize volume per unit surface area (1 e. a spherical gram) Available data on genetic variability for grain size indicates that it should be possible to increase the gram size of Australian wheats by 50-100% and improve potential milling yields by 2-3%. However, while considerable genetic variation for grain shape also exists, the evidence available suggests that selection for optimal shape is likely to result in a correlated reduction in seed size thereby offsetting any gains achieved by changing seed shape.