The physiological life cycle of wheat: Its use in breeding and crop management (Reprinted from Wheat: Prospects for global improvement, 1998)

Efforts to model winter wheat (Triticum aestivum L.) crop growth and yield have required scientists to define processes in wheat physiology and to link knowledge of physiology with detailed descriptions of phenology. The use of precise visual plant staging to express different phenological phases of wheat has allowed modellers to define such features as: the specific organs available for growth; resource allocations to tiller, root, and leaf growth; above versus below ground distribution of dry matter; and timing of phenological events. Use of cumulative heat units (growing degree days) to drive cereal development has simplified the expression of some of these relationships. This paper presents phenological aspects of wheat development used for modelling and will discuss how this information might be of use to breeders and crop managers concerned with selection and management of plant materials. Cultivar properties such as stress avoidance, timing of critical stages, and harvest ratios as well as management factors including spray schedules, fertilisation timing and amounts, and planting geometry can all be examined for their impacts on production by use of models. These are the types of properties that breeders can use to improve yields.