TOWARDS THE RELIABLE PREDICTION OF TIME TO FLOWERING IN 6 ANNUAL CROPS .1. THE DEVELOPMENT OF SIMPLE-MODELS FOR FLUCTUATING FIELD ENVIRONMENTS

Despite numerous attempts, the development of generalized 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 f with various states of environmental factors such as photoperiod, P, and temperature, T, using formal statistical procedures are 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 f but on 1/f, 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.