a1 University of Reading, Department of Agriculture, Plant Environment Laboratory, Cutbush Lane, Shinfield, Reading, RG2 9AD, England
a2 CSIRO Divison of Tropical Crops and Pastures, The Cunningham Laboratory, 306 Carmody Road, St Lucia, Brisbane, Queensland 4067, Australia
Despite numerous altempts, the development of generalixed models capable of accurate predictions of the times from sowing to flowering (f) of crop plants in field environments has remained elusive. Models which seek to correlate ; with various states of environmental factors such as photoperiod, P, and temperature, T, using formal statistical procedures arc often complex. Here, we describe a family of photothermal responses (involving unambiguous parameters and limits) which quantify the linear, non-interacting effects of P and T not on but on 1/, i.e. on the rate of progress towards flowering. Based on these relations we suggest that the modelling of crop phenology will be simplified, more reliable and more biologically plausible.
(Accepted July 09 1990)